BG-272 DIY 2 x 72" Belt Grinder

DIY 2" x 72" Belt Grinder Project


Like almost every newbie knifemaker owning a decent belt grinder is dream. When I realized the price of a machine, my jaw hit the floor. Most of us getting started cannot afford a $2000 grinder. So I set out to design my own and I shamelessly borrowed as many ideas as I could. One special shout out to Alaskabearhawk for his great design and detailed videos on YouTube.
















Wish List

My wish list for my new grinder would be:

  • 2 x 72" belts
  • 1.5 to 3 horsepower
  • Variable speed
  • Removable attachments, platen and contact wheel 

Variations


Before building I considered some variations:

Stepped sheaves for varying speed. This would be a lower cost build, but still allow some speed changing. I would need two pillow blocks, an axle and a stepped sheaves (or pulleys as some folks call them). The drive wheel could be 4" diameter still. This arrangement would let me use any motor, whether it can be reversed or not.

Fixed speed would be lowest cost and simplest build as there are less components and less alignment issues. The motor can be 2 pole or 4 pole and must be rotating in the CCW direction. That's fairly easy. Drive wheel size becomes a focus. For a 1800 RPM (4 pole) motor I'd use a 5" or 6" wheel. 2335 or 2826 surface feet per minute. For a 3600 RPM (2 pole) motor I'd use a 3" or 4" wheel. 2826 or 3768 surface feet per minute.

To get the surface feet per minute, use the formula:
(Motor Speed in RPM x 3.14 x Wheel Diameter) / 12.


Take a look at some of the other builds on the BG-272 Gallery of Builds page. Some very clever ideas going on there. Thanks to all that sent in photos and made such great suggestions.


Procurement

The search for suitable wheels proved fruitless as the most common maker in the US did not ship to Canada at the time. I found these wheels from Europe on eBay. You may want to check out Oregon Blade Maker's belt grinder wheel set.














Note: If you want to machine your own wheels, here is a PDF and a CAD drawing graciously provided by K. Langeveld.








For the drive wheel, I am using a 4" nylon caster that is 2" wide. I had to push the roller bearing race out and insert a shim with a 7/8" inside diameter. I then had to cut a key way for the 3/16" key stock. A fair bit of work, but I have made what is effectively a sub $20 crowned drive wheel.




The motor came from an ad on Kijiji . I scored this 2 horsepower T145C face motor, 3 phase 230/460V for a whopping $35. I wasn't too sure about this but after a quick ohm meter test and a spin of the shaft I think we're going to be fine.

For the variable speed part, I chose a Yaskawa J1000 VFD. My work associations with Yaskawa have been top notch over the years and basic shaft spinner came into my hands at a very reasonable price.

I am going to install the VFD in a sealed enclosure (NEMA 4) and wire a control panel for the operator to start, stop and vary the speed of the motor from the front of the grinder.

For the basic electrical I sourced from eBay, Digi-Key and my locals like Home Depot, Canadian Tire and Peavey Mart.


Not everyone can chance upon a nearly free motor.  I have made a Belt Grinder Motor Guide to help you in selecting a motor. Aside from a few electrical things, remember to check the shaft size on the motor and make sure the drive wheel's bore is a match. Drive wheels usually come with 5/8", 3/4" or 7/8" bores.






Construction

The basic construction is of HSS (Hollow Structural Steel) pieces and some plate and scrap pieces from my shop and from Metal Supermarket. The pieces I cut on a band saw so they are nice and square.

I bought 48" of 2" HSS, 0.188 wall and cut them like this.

















Very important! You must remove the seam inside the 2" HSS receivers before any welding takes place. This seam will prevent the inserted 1-1/2" tubing from sitting square inside their receiver. Use a long file or a small grinder wheel in a drill with an extension and remove the seam. Once the frame is welded, it becomes much more difficult to do this with a file.

As suggested by Ken DeRosier, make sure the welded seams are positioned on the left (where the lock down nuts will be installed.) This reduces the seams from being an issue, and provides a perfectly flat face for the tool arm to rest against.

Pieces A, B, C and D are squared, clamped and welded to make a frame like this.
















































I drilled some holes and tacked some 3/8" NC nuts for the lock downs.

I then welded the frame to a 12" x 20" plate of 1/4" steel, again checking for squareness and clamping everything in place before tacking.










I added four 1/4" x 1-1/2" studs for mounting the motor. These are flat head capscrews and I countersunk the underside so that they didn't stick out. I used hex nuts and placed fender washers on to support the motor. These being a bit smaller than the motor foot mount holes, allows for some rotating of the motor to get the belt to track properly. Also a  6" piece of strut to mount the operator control panel. The motor is positioned so that the center of the shaft is about 4" to the back of  the vertical receiver.




30 pound spring. Thanks Dave! I measured this on a scale. Pressing down on the spring about 30 pounds caused it to deflect 1". More recently, we have found that springs from screen door chains will work okay.






Update March 2017. I have made some better drawings of the frame.




























Tracking and Tensioning Pillar


The tracking and tensioning pillar slips into the upright receiver part C of our frame and sits on top of the spring. It has a tracking hinge that can be adjusted to tilt the tracking wheel.











The hinge part has a hole drilled right through, 3/4" from the top and 1-1/8" from the left side as shown. This hole is slightly larger than the 1/4" bolt that will act as the hinge pin.

The axle hole is 2" from the top, centered.



The pillar itself is 13" long. This may have to change depending on the spring that you have available. My spring is about 4" long, so add or subtract a little if your spring is shorter or longer.

The axle hole is 3/4" from the top and drilled right through. See photos below for construction.



The cutout hole for the tracking wheel axle is 2" from the top of the pillar so that the head of the axle bolt goes inside of this cutout. If you use a carriage head bolt for the axle, you need only make a round hole.




I clamped the hinge with shims around it before drilling a pilot hole right through both pieces on the drill press. Add 1/16" shims on the sides and 1/8" on the face. 







I tacked a flat washer on either side then hit them with the belt to thin them down to a good friction fit inside the hinge piece. The pillar will need an area removed for the bolt head of the tracking wheel axle to come through. If you were to use a carriage head bolt, this could be a circle. I had no luck finding a 12 mm carriage head, so I made a square to fit the hex head of the bolt.







 Test fitting the hinge.









The top and bottom of the pillar get capped with some 1/8" flat bar. Before tacking the top plate in, I drilled and inserted 5/16" x 1" bolt, then tacked that around the head. This will be for my shifter ball. (The ball will make it easier to push the pillar down.) 
Also note the 1/4" nut mounted for the tracking adjustment knob. The bolt going through here will press against the tracking wheel axle bolt and allow the tilt of the hinge to be adjusted.






The Platen Attachment

The platen attachment slide into a receiver and is locked in place. The tool arm is of 1-1/2" HSS with 0.250" wall that is 17" long. The plate that the wheels attach to is 3" x 12" made of 3/16" steel. I set the holes 10-3/8" apart so as to leave a good amount of space between them for a 9" platen. The platen is made from a piece of 2" angle iron. The angle is 0.188" thick.

I put a backing piece of 1/4" plate behind the angle to step it away from the plate. This could be accomplished with a small stack of flat washers as well. This space is to bring the platen directly in line with the belt and wheels. If you need to tweak the platen to the left or right, add or remove a washer from three bolts securing the platen to the plate.

The wheels are mounted typically with 1/2" bolts. In my case I have metric wheel bearings, so 12 mm bolts. The wheels cannot run against the plate, so I made some spacers from schedule 40 3/8" pipe cut into short sections about 1/4" and with a hacksaw and shaped with a file to uniform thickness of close to 3/16". Slip the spacer over the bolt, slide the wheel on and the inner race should be kissing the spacer.

Below are some updated drawings for the flat platen.








Tilt adjustment is made by loosening the two bolts and and adjusting. Once in the correct angle, lock the plate in place with the two bolts.







For the work rest, a found a piece of 1/4" thick plate about 4" x 6" and welded a piece of 3/8" x 3/4" bar stock to it. I drilled and made two slots for the 1/4" NC socket head capscrews to secure to the bottom of the tool arm.

Note that this work rest has been replaced with the Adjustable Work Rest.






Test fitting and tracking evaluation. Before painting, I added a 1/4" x 1/2" bolt on the vertical piece so I could mount a brush to remove static charge from the belt.

One thing to note here. The pillar is a little bit loose inside the vertical receiver. I added two strips of plastic (from an old oil jug) to act as shims. These are dusted with a little graphite to make them slippery.









Unit painted.


Added the tool rest made of 1/4" plate on a 1/2" x 3/4" flat bar mounted to the underside of the platen tubing with 2 tapped 1/4" holes and hex socket capscrews to match.

Powered up the motor for live tracking test and VFD programming.







Grabbed two extension cords from different plugs in the garage and made 240V. A little high but should be ok. See the section on VFDs if you want to source 240V.
Powered up the VFD for initial programming.








VFD Power Wiring

The VFD requires a 240V / 20A supply. I have opted for a NEMA L6-20 receptacle and plug. The L means 'Locking' and this will assist in preventing any accidental un-plugging of said plug. I am using some supple SOOW 3 conductor #12 AWG for the input connection. I'd like some length so I piked up about 15 feet of this. Inside my VFD enclosure I have two midget type fuses that protect the VFD proper. A low current takeoff of 240V for the DC power supply is done immediately after the fusing. For convenience I've added some surplus terminal blocks mounted on DIN rail. The output of the VFD is rated for 10A (three phase) so I used some 4 conductor #14 AWG SOOW (cab tire) cable.



 

 


Operator's Control Panel

To control the VFD I am going to bring out the sequence inputs SC, S1, S3 and S5. This will allow me to START and STOP the motor as well as change the direction FWD and REV. I will also wire in the VFDs status contacts to drive two LEDs indicating motor on and off. Finally, I have a digital tachometer that will count pulses from a small magnet placed in the side of the drive wheel. The net result is that the operator's control panel will look something like this.






The magnetic (Hall effect IC) sensor that picks up magnetic field from the small magnet inserted into the drive wheel.








When the magnet passes close to the sensor the sensor switches to make a 24 VDC pulse going to the tachometer. This will count the revolutions per minute of the drive wheel.







To install the magnet in the drive wheel I drilled a 3/8" hole about 1/4" deep. Put a small daub of epoxy and pressed the magnet in with a vise.






The Hall effect sensor is mounted on the C-face of the motor and positioned about 1/4" away from the wheel so that the magnet passes near it each revolution.


Drilling the holes to get the jig saw blade in.
Masked off the face for drilling, jig sawing and filing the various cut out shapes.
Test fitting the tach.

Control and tachometer cables with strain reliefs in back of operator control panel enclosure. For the cable, I found some old-school 25 pin printer cable that has an overall shield.






Once the VFD enclosure was mounted to the frame, I could terminate one end of the control cable  accurately estimate the cable length for the motor. The control wiring is fairly straight forward. One thing to pay attention to is the wire colours. The particular printer cable I had has insulation that is colored solid and some with white stripes. These can be easy to mix up. A quick check put with the ohmmeter will save the day and prevent a mistake here.

I ended up with multiple wires going to +24V and common. I used some small wire nuts (Marettes), twisted all the +24V wires and cranked a wire nut on. As the LEDs already had wire leads on them I did solder splices and covered with some 1/8" heat shrink.







VFD Enclosure

The VFD enclosure is a surplus Hoffman NEMA 4 14" x 18" x 8". As it did not come with a mounting pan, I had to make one from something. Conveniently, I found some 1/8" utility grade aluminum that was pretty scratched up, but the price (free) was right.


I mounted the VFD and 24V power supply as well as some DIN rail to mount the terminal blocks.

For strain reliefs I used some nylon domed strain reliefs and one Heyco straight-thru for the tachometer sensor cable.





Tying it all Together

With the incoming power cord attached and the 4 wire motor lead connected it was a matter of programming the VFD to accept the 0-10V input (potentiometer) as the speed command and setting the top frequency to 80 Hz.  I also set the acceleration time to 5 seconds and deceleration to 2 seconds.



 



 

Running The Grinder

The first run with the unit complete involved a little tweak in the tracking hinge. The belt ran fairly true and didn't walk off the wheels at 4500 RPM.

 



 


 



I took a chew through some 154CM and the blaze belt eats it like butter. I am so impressed I will toss my hacksaw out!



 

 

 

 

Grinder Stand

The stand will hold the VFD enclosure and the grinder will be mounted on the top. For this I chose some scrap channel I had and welded it up. Adding two casters on the rear will allow easier moving, but only when tilting.


Before painting this space-ship silver, I welded some 5/16" x 1" flat head bolts to act as mounting studs for the grinder base.

Knowing where the motor and VFD enclosure line up, I can drill some holes for some chase nipples to pass the motor cable and control cable through the grinder base plate.







Small Wheel Attachment

July 8, 2014 - Small Wheel Attachment is now here.














10" Contact Wheel Attachment


October 2014 - 10" Contact Wheel Attachment is now here.


















Always updating. I will keep you posted.

Mechanical Bill of Materials is here.

Updated April 2017

Dan


168 comments:

  1. fixing to build one of these, this is the simplest design I have found that can use attachments from the kmg design as well like the small wheel attachment. hopefully by the end of the month I can start on it. thanks for posting this.

    ReplyDelete
  2. You are welcome. Take a look on YouTube for 'alaskabearhawk'. I own him kudos on the design. I've been grinding for almost a month now and loving it. It's got power and tracks well. All I need now is a dust bucket and water pot.

    ReplyDelete
  3. Where did you get your blue drive wheel?

    ReplyDelete
    Replies
    1. Hi Tommy,

      The blue drive wheel is actually a 4" caster that I bought from an industrial supply place. I popped the bearings out and pressed a bushing with a 7/8" inside diameter and broached a keyway. It's domed already and works great for under $30.

      Delete
  4. Would you be willing to build another one? How much would you charge for this exact setup?

    ReplyDelete
  5. Due to workload and parts availability, I would be unable to make another grinder like this. My next one I will buy and get a motor and drive for it. I would recommend you contact Terry at: http://www.sahtudesigns.com/products/tdm-basic-grinder

    Cheers,

    Dan

    ReplyDelete
    Replies
    1. Website changed to: http://www.2x72grinders.com/post?id=8248245

      Delete
  6. Can I ask why you will buy your next one?

    ReplyDelete
    Replies
    1. Hi Paul,

      I do love to engineer stuff and the sense of satisfaction that comes with making a truly useful tool is second to none. I am very proud of the BG272 and use it almost every day. However, more recently with job and family I am having a lack of time issue. I really love to make knives and if I had a choice between making a grinder or making a knife, I'd get someone else to make the grinder. Personal choice only given the circumstances. Grinder makers do what they do best. Knife makers do what they do best.

      As a side note, I still use files and sandpaper. :-)

      Merry Christmas!

      Dan

      Delete
    2. i just noticed you pretty much answered this directly above my comment, sorry. I just finished building my grinder and HT oven, i could see myself buying a motorless one for 800 bucks maybe just to save on building it and finding parts.

      Delete
  7. Tensioner idler wheels removed as a matter of course when replacing automotive timing belts are a great source of very high quality, very high speed capableidler wheel.

    They come in many dimensions and are give-always at most auto repair shops.

    ReplyDelete
    Replies
    1. Yes, great advice. I learned this from Alaskabearhawk. His wife's Subaru timing belt change was a big part of his flat platen design.

      Cheers!

      D

      Delete
    2. I have been looking at idler wheels but they all seem to be about 1" wide. Don't you need 2" wide wheels to match the 2" wide belt?

      Delete
    3. Randy,

      Yes. I would think a 1" wheel would be too narrow. Most are between 2" and 2-1/4" wide. I used 2" wide idlers.

      Dan

      Delete
  8. Awesome design, but I do have a couple of questions.

    What size is your compression spring, and what is the distance from the back of the frame, to the center of the contact wheel?

    Thanks!!!!

    ReplyDelete
    Replies
    1. Hi Chase,
      The distance from the pillar to the centre of the wheel is 4". This could be adjusted depending on the size of the drive wheel and the length of the pillar, spring and tool attachment.

      The spring I used was 3/4" diameter x 4" and compresses about an inch with a 30 pound load. Any reasonably short spring that fits into the vertical receiver that compresses around 30 lbs. will work.

      Delete
  9. Hi there, thanks for the awesome tutorial. I'm wondering what size you chose for the aluminum wheels (ouside and also maybe the inside if you know off the top of your head).

    Also what kind of taper does the tracking wheel have on it? I'm close to a machine shop here and wondering how to describe the specs on that wheel to them.

    Cheers :)

    ReplyDelete
  10. Nick, please email me. I think I have something on file. knives/@/dcknives-dot-com

    ReplyDelete
  11. Thanks Dan will email you right now!

    ReplyDelete
  12. Thanks for your ideas. You can also find the details on Drive Parts Direct, at the Toothed Belts. Drive Parts Direct aims to provide you with a convenient “one stop shop” for all your Power Transmission component requirements.

    ReplyDelete
  13. How easy is it to change belts, I dont see any handle or other things to help depress the spring to change belts.

    ReplyDelete
    Replies
    1. Hi Andrew,

      Changing belts is a easy as pushing down on the 8 ball and releasing the belt. Start the belt and press down the 8 ball, then fit the belt over the dive wheel. Release the 8 ball the spring pushes up and tensions the belt. It take about 10 seconds to swap belts.

      Dan

      Delete
  14. I built one like this but am having trouble with the tracking. How did you line up the wheels to get the initial tracking straight? I can get it straight with the tracking wheel but have to nearly go to the extreme to get it tracking properly.

    ReplyDelete
  15. Hi Gregory,

    Without seeing a photo it's hard to tell where the tracking is off. I used the same thickness (0.188") of steel everywhere, so that the tracking wheel hinge was in line with the outside of the vertical receiver part "C". When making the flat platen, the plate I used was also 0.188" and I used the same spacer (washer count) on the tracking wheel and the two platen wheels. This should get all three wheels to line up. The last wheel to deal with the drive wheel off the motor. Some shims or washers may be required to get the drive wheel to "tilted" correctly. My drive wheel is on a keyed shaft with a set screw so I can slide it in or out to align with the other three wheels. If you send me a photo or two I may be able to assist you better. Email: knives -at- dcknives dot com.

    ReplyDelete
  16. Thank you for the response. I used the same thickness of steel as your instruction describe 0.188" everywhere. I recounted the number of washers (spacers) and they are aligned. I think the problem then is my drive wheel. I will work on it some more. Also, I will send you pictures.

    ReplyDelete
  17. Hi Dan,

    This is one simple design. Very, very nice! I like the tension and tracking design. I'm looking into building this same design except I'll be using a pulley instead. Your entire design was very well thought and simple. When I'm completed my grinder I'll send you pictures. Thanks for the great design and schematics.

    Jimmy Nguyen

    ReplyDelete
  18. This comment has been removed by a blog administrator.

    ReplyDelete
  19. Cannot thank you enough for posting this. Was wondering if you had a source or more detail on the 30 Lb. spring. Wanted to make sure I got one the right diameter and length.

    ReplyDelete
    Replies
    1. Hi,

      Unfortunately, the spring was given to me and I have no idea where it came from. The spring I have is about 1" in diameter and about 5" long. It takes about 30 pounds to squeeze it about an inch. A little bit shorter or longer is okay as you can slide the tool arm in and out of the receiver to compensate for variations in the spring.

      Delete
    2. The storm door spring works great. About $6 from Lowes

      Delete
  20. Looks great! Enjoyed the pictures and the info. The only problem i think i'll have with my build will be finding the spring. Any ideas where we can find the spring?? maybe a used one off something that gets throwed out and can pick one up on the cheap, i hope. Please post any info you can on this would be a huge help. Thanks, Rick.

    ReplyDelete
    Replies
    1. Hi Rick, I've heard all sorts of springs being used. From front shock of motorcycle springs, to storm door chain spring to the spring from the back of an office chair. It needs to deflect 1" with about 30 lbs force and fit inside the vertical receiver.

      Delete
    2. Thanks, will just have to experiment around a bit. Happy Thanksgiving bud. Rick.

      Delete
  21. I live in Europe and can't find a place to buy the wheels from. Do you have any idea if the ebay seller still have some to sell?

    ReplyDelete
    Replies
    1. I got mine from Cile159. You will have to check his page on eBay and see what he has for sale.

      Dan

      Delete
    2. ebay seller oregonknifemaker has them and they are decently priced with good reviews. i just bought a full set.

      Delete
    3. I just finished mine. I used the oregonknifemaker poly wheels on it. They work great

      Delete
  22. Thanks for the awesome tutorial !!! I just finish bilding one and I have a small problem...when I put pressure on the belt (with a blade ), this one moves to the right for about 3/16 of a inch. Would you know why ?

    ReplyDelete
    Replies
    1. What is your belt tension? If you have about 30 lbs tension on the belt is should track well. Most belt issues are due to tension. I put my spring on a scale and pressed down. About 30 lbs squished the spring about 1".

      Delete
  23. Here is the one I am building at about 90% using the information you provided along with some extensive research. Please ignore my bobo welding job. I learned while building this. I am using a treadmill motor that I turned a bushing for that is reverse threaded and turns the shaft into a 3/4 inch shaft. I got the wheels from Oregon Blade Maker's eBay store. They are incredible and all of the wheels including drive, tension, and two idlers were 106.00. It was amazingly easy and I learned a new skill, Welding while I was at it. All in all I paid 47.00 for steel from the metal supermarket. (These guys were incredible) They cut all of my parts to size for me and sold it to me at a great price, The price for the same stuff at online metals was around 235. So far I have 153.00 in the whole thing and a Hobart really nice welder, I would post pics buy can't figure it out. I just wanted to say thank you for posting the information as in was the one thing that helped me to succeed.

    ReplyDelete
  24. Great write up and layout. I have looked at several and yours is as good or better than most. Great job.
    I do have one question. Most of the belt grinders I see only have one horizontal piece. You have two, A and B as labeled in the drawing. Why do you have two? Is it a structural issue I don't see? I would appreciate your input.
    Thanks
    Kevin

    ReplyDelete
    Replies
    1. Hi Kevin,

      The second receiver can be used for a tool rest, light or other attachment you may wish to develop down the road. I use it for my adjustable tool rest.

      Delete
    2. Thanks for the reply. That makes sense.
      Kevin

      Delete
  25. Hi Dan,
    It's been great reading your posts on diy tools etc.

    Can you offer any more detail on the step to replace the castor bearing with a shim and cut a keyway?

    Is it just a case of using the appropriate internal diameter pipe to fit the drive shaft and finding a method to cut a small section away to allow the key section of the driveshaft to slot in?

    Did you have to drill a hole to allow for a keyway screw?

    Thanks,
    Daz.

    ReplyDelete
    Replies
    1. Yes, the bushing is 7/8" inside diameter which is a match for the motor shaft. Luckily the outside diameter of the bushing is a press fit into the inside of the wheel. So into the hydraulic press and it slid right in nice and tight. However the there is no keyway in the bushing, so I used a file to cut one in. Then I drilled a 1/4" hole through one side of the wheel until I hit the bushing. Then I switched to a 13/64" bit and drilled through. Ran a 1/4"-20 tap through and inserted a 1/4" set screw. Ta da!

      Cheers,

      Dan

      Delete
  26. Hi Dan,
    It's been good reading all your write-ups on diy tool creation - appreciate the time taken to document all these steps.

    Quick question if you have time: When replacing the castor bearing with a shim including a keyway, was it just a case of using the correct internal diameter pipe to fit the drive shaft and then cutting a notch to allow the driveshaft key?

    Did you also drill a hole for a keyway screw or was that not required?

    Thanks,
    Daz.

    ReplyDelete
    Replies
    1. Yes, exactly. The motor shaft was too small to fit inside the caster once I popped the roller bearings out. The shim was off the shelf and I interference fit it (pressed) in into the caster. The keyway is required to lock the wheel to the shaft, so I had to broach the inside of the shim.

      Dan

      Delete
    2. I drilled a hole in towards the shim that lines up with the keyway. The hole was 7/32" so I could run a 1/4" 20 tap through the shim and have some threads for the setscrew to bite on.

      Delete
    3. Thanks Dan for generously sharing with us these info

      Delete
  27. Hi i was looking for good ideas to make my grinder and i just found the best and easy ones thancks great job nothing complex on it you just make my day thanck you bery much

    ReplyDelete
  28. thaks , i was looking for good ideas for building my grinder and i just found the best ones, glad i found your page , seems easy i will try it it wont be a clone but something close i hope ,, thanks againg keep up the good work

    ReplyDelete
  29. Hi dan where is a good place to buy the belts here in Alberta.?

    ReplyDelete
    Replies
    1. I get my 2x72" belts from Canadian Knifemaker Supply in Sundre, AB.

      Delete
  30. Excellent. I had an idea to make a curved platen for hollow grinding without the big wheel. Have you tried this? My concern would be about belt friction over the platen. Other than that I think it might be a simple and relatively cheap solution to the big wheel. Thoughts?

    ReplyDelete
    Replies
    1. Hi Chris,

      I have seen this done on 1"x30" grinders where the belt is backed by an arc. I should work on a 2" belt as long as, as you mention, can keep it cool. Graphite, slower speeds? I am not 100% sure. It would be worth a few trials.

      Dan

      Delete
    2. Trying to figure it out along with some other handy bevel jigs. I made a grinder from your blue print. Works great!

      Delete
  31. Hi, I'm working towards building one of these grinders, single speed initially, just gathering parts at presents. I'm a little confused however with regards motors and wiring. I'm looking at this motor http://pages.ebay.com/link/nav=item.view&id=280542675462&alt=web and wonder if I'll need a DOL soft start switch, or can I just use another type of switch.

    Thanks
    Matt

    ReplyDelete
    Replies
    1. Hi Matt,

      I can't get to the link on eBay. Is it a single phase 115V kind of motor? Motors up to 3 hp 230V can be controlled with a typical start/stop switch like this one: http://www.ebay.com/itm/WoodStock-Start-Stop-Switch-On-Off-Push-Power-Button-Single-Phase-Lock-/131763527373

      Dan

      Delete
  32. Hi Dan,

    Sorry I think I gave you a link to my wish list, this should be correct: http://www.ebay.co.uk/itm/Electric-Motor-Single-Phase-1-1Kw-1-5HP-4-pole-1400-rpm-/280542675462?hash=item4151a58206:g:UNkAAOxy63FS86Sf

    It's a single phase 250v motor, so suppose I have to look for a higher rated switch.

    I'm in the UK if that makes any difference.

    Matt

    ReplyDelete
    Replies
    1. Hi Matt,

      That motor would work fine on a grinder. The mains power needs only to be switched on and off. The motor, being a 4 pole, runs around 1400 to 1500 RPM. You will want a fairly large drive wheel, at least 5" in diameter to get the belt speed in a good range. Otherwise, you can use two stepped sheaves and a V belt to vary the speed.

      The switch is likely rated for 250 V, but the ratings for horsepower are 230 V (typical motor spec. in North America).

      Cheers,

      Dan

      Delete
  33. This comment has been removed by the author.

    ReplyDelete
  34. what did you use for start stop and reverse switches. I am using the same VFD. Thanks

    ReplyDelete
    Replies
    1. Hi, I used some 22 mm momentary pushbuttons like these at Amazon.com for the Start and Stop. For the FWD/REV I used a generic automotive rocker switch.

      Delete
  35. Is there any way you could post a drawing and/or complete parts list for the grinder and the two attachments. I have a shopsmith mk5 lathe that I plan on using this design for, except it will be mounted to the lathe on removable platform.

    ReplyDelete
  36. Hi Dan
    I have just completed a build a sander with the same principle as the one you have built with the direct drive. Currently only have one speed got it going for the first time over eh weekend and i have a problem the belt runs straight off the side when its running across all the wheel no adjustment to the tracking wheel makes a difference. Yet if I run it with out the tracking wheel & tension the belt tracks perfectly. Any clue what I've done wrong?

    ReplyDelete
    Replies
    1. Try adjusting the position of the motor. I had to shim the right side of the motor with some washers to "point" it at the tracking wheel. It really depends on the squareness of the vertical pilar to the base. Also, wrap a few wraps of electrical tape on the center of the drive wheel and see if that helps.

      Delete
  37. Hi Dan,
    I am setting up to build a belt grinder like yours. I have a question about the tracking pillar. I have seen a few other builds where they said that the pillar was a bit loose in the receiver and they had to remedy that with plastic shims. Was yours a tighter fit, or do you have some play in the tracking pillar and it just doesn't matter?
    Thanks
    Randy

    ReplyDelete
    Replies
    1. Mine was about 1/8" total clearance (or 1/16" on each face). I used some strips from a plastic oil jug as shims. This created a fairly tight fit. Then I added some graphite powder to make it slide easier.

      Delete
    2. Did you try running it without the shims? Does it just rattle a lot or does it effect the tracking? I guess I am wondering because I was considering changing the design to an arm styled tensioner if it took a lot of fiddling around to firm up the tracking pillar in this design.

      Delete
    3. I did not run it without the shims. The tracking wheel can be slightly off on the X and Y axis, but needs to be very close on the Z axis. This helps immensely with tracking. If your vertical receiver is not perfectly square on the Z axis you can "tweak" this design with the plastic shims.

      It's really a set and forget thing. I've never had to make any further adjustments to the grinder since 2014. I do add some graphite every year or so.

      The big issue is the weld seam inside the 2" HSS. It's very important to ensure the seam is on the left (not the belt side). The tracking pillar can then rest flat against the right wall of the 2" vertical receiver. Then the only play to be concerned with is the gap on the front and back.

      Some guys simply tack a strip of thin steel on and grind it where needed. Blob some grease on it and go.

      Dan

      Delete
  38. Dan, I love your design and detail and sharing it with us. I started mine with 1/4"x 2" tubing and 3/16"x 1.5" for the inside tubes. The radius fits just perfect on the inside of the larger tubing. But it took quite a bit of work grinding out the welds - thanks for your tip. I haven't welded nuts yet. I just threaded the 1/4" thick tubing for my lockdowns. I think that should be enough.

    I have a question about your platen. It looks to me like your angle iron slots would prevent the whole assembly from rotating very far. Did you have a problem with that?

    Also, where did you get the tachometer for your motor? Is that the right name for it? And what kind?

    So far I have spent $31 for steel. I plan to order the wheels from Oregon. We have a couple of 3 phase fan motors taken out of a warehouse. I was thinking of using one of these with a VFD. I did not know that VFD's could power a 3 phase motor on single phase. However they are not TEFC motors. American Surplus has TECO vfd's for about $150. Would that work?

    Thanks again

    ReplyDelete
    Replies
    1. Hi Rick,

      The slots in the angle allow the platen to move in and out. The platen itself will rotate about +/- 30° from the normal right angle. The idea was to allow for adjustment for when using a work rest. To be honest I have never unlocked it from 90°.

      The tachometer is a very basic automotive one I bought from a vendor on eBay. I used the magnet inside the drive wheel and a hall effect IC to make a pulse every revolution of the wheel.

      Yes, the TECO VFD will work fine. You will likely need 240V as most drives over 1/2 horsepower need more jam than the basic 120V can deliver. The fan motor will be okay, however not as ideal as a TEFC motor. Remember to blow it out with compressed air or if you can enclose it a little to keep the dust out as best as possible.

      Cheers!

      Dan

      Delete
  39. Hello Dan - that is a nice looking control panel (and grinder) you've built. I've looked and have not been able to find where you tell about the digital display. You mount the magnet and hall sensor in drive wheel so you're able to read RPM directly, rather than depend on what the VFD says RPM should be. What digital display did you use? Thanks, Ken H>

    ReplyDelete
  40. Hi Ken,

    The VFD that I have does have an analog output that could be hooked up to a voltmeter and calibrated to show the speed. More expensive VFDs have remote displays that plug into the VFD proper, but there's extra cost in the displays too. Some VFDs will display Hz, but that's not the same as RPM as there is slip and two pole motors run twice the speed of four pole motors at a given frequency.

    I simply used an $8 automotive tachometer from eBay and pulsed it with a magnet and Hall effect IC. The magnet is mounted in the drive wheel and the Hall effect circuit is positioned near the wheel. Like an old-school reed relay the magnet opens and closes the circuit each revolution of the wheel. This is super reliable. Having a 4" drive wheel also means that RPM reading is very close to the Surface Feet per Minute value.

    As for the actual tach I used, I believe this is the link: http://www.ebay.com/itm/0-56-LED-Display-Digital-Motor-Tachometer-Speed-Measure-Meter-panel-30-9999RPM-/190898639450.

    Cheers!

    Dan

    ReplyDelete
  41. Dan, Thank you for such a fast response. That is one slick tach and very cheap. A couple yr ago I used an Arduino chip to read input from a Hall sensor for RPM on a lathe - using a 2 line LCD I was able to add a rotary encoder to enter work diameter to give tool speed on the tool. This is a much simpler solution.

    Ken H.

    ReplyDelete
  42. Dan, Thanks a bunch. I built a 2x72 based on your design, and it rocks! I didn't use hollow structural steel for the body, I used 1/4 inch wall 6061-T6 aluminum hollow square for both the rigid part and the slidey parts. Also I used a 40 pound air spring for tension. I have a lathe so I cut my own wheels, and I tig welded the base together. I used an old motor from a Harbor Freight table saw, and made a 5.1 inch wooden drive wheel. At first I had a base plate of very light aluminum, like 1/8th inch, and had everything mounted to that. NO GOOD! There was so much flex in the base that you would adjust the tracking and apply a workpiece to the belt, and the base would deflect enough to make the belt fly off. So I cut up a piece of 1/4 inch plate steel, and mounted everything to that and all is well now. Belt tracks stable, cannot deflect the motor or the body of the grinder at all now. Mine is only single speed, and pretty fast, so I'd like to get a 1.5hp motor and VFD, but my grinder is usable now, and I use it all the time.

    ReplyDelete
    Replies
    1. Sounds like an awesome machine! I'd love to see it if you have a photo or two. Drop me an email at knives -at- dcknives.com

      Cheers!

      Dan

      Delete
    2. Hi
      Is it necessary for the wheels to have Bearings? Also, if I'm buying the spring from a shop, what do I tell them?

      Delete
    3. Yes, the wheels need bearings. They rotate at high speeds (especially the smaller diameter wheels). The spring you need will be about 1 to 1-1/4" diameter, 4" long and has a rating about 30 lbs.

      Dan

      Delete
  43. Hi Dan,
    I was just wondering about the position of the motor, in particular its distance from the rear of the unit and whether moving it further back would have any unwanted effect on the tracking wheel / tension etc. The reason I ask is because i would like to make the tool arm shorter, enabling me to make a second arm for the tool rest out of the stock I have available.
    Cheers
    Matt

    ReplyDelete
  44. Although I have never tried moving the motor on mine, I don't see a problem with moving the motor further back. As long as all the wheels stay on the same plane. The KMG style has the tracking wheel about 1/2 way between the motor and the platen/large wheel. Please let us know how it goes!

    Dan

    ReplyDelete
  45. Hi Dan,
    I've collected all the parts I need for my grinder and I'm mocking parts up. When it comes to attaching my idler and tracking wheels I'm unsure as to how far I should tighten the bolts against the wheels. I am worried about impairing the bearings. How much free spin should the wheels have?

    Matt

    ReplyDelete
    Replies
    1. Hi Matt,

      Tighten the nuts to hold the wheel without slop, and yet the wheel will spin freely for a few turns when spun with your hand. Use a nylon locking nut or two nuts that are locked together against each other. This will keep the outer nuts from working loose under vibration.

      Good luck!

      DAn

      Delete
  46. I've got a 1.5hp 3ph motor at 1750rpm. I saw that you recommend a 3600 rpm motor - but this one was free! If I get a 2hp vfd will that combo work OK or should I try to get a faster motor? SUrplus Center has 2 hp TECO VFD's for around $199

    ReplyDelete
    Replies
    1. Hi Rick,

      I recommended a 3600 RPM motor to save costs on the drive wheel. 1800 RPM motors are better suited to 5 or 6" drive wheels, whereas 3600 RPM motors are good with a 4" drive wheel.

      If you know the drive wheel size, you can better choose the motor. I have a chart on this page that can help with the speed calculations.

      Delete
  47. Hi
    The belts available in my city are 50*2000mm, or like 2x78
    Can you suggest any modifications so I might be able to use those?

    ReplyDelete
    Replies
    1. Hi Varun,

      The grinder will work with 50x2000mm belts. The tool arm can slide out to make up the difference.

      Regards,

      Dan

      Delete
    2. Also, I bought a Bench Grinder with 2800RPM
      Can you suggest the Drive wheel size to attach on that?

      Delete
  48. Hi Varun,

    A 4" drive wheel will be fine at 2800 RPM. That will put your surface feet per minute at around 2930 or so. A 5" wheel would be at 3665 sf/m.

    ReplyDelete
    Replies
    1. Hi
      I know this is totally unrelated to the post, so I'd like to apologize first

      So while I was working on a Tanto recently, my Blacksmith quenched the blade in Motor Oil. Now I would like to bring to your notice that the concept of re-heating the blade in an oven does not exist here in India. People just quench the steel in motor oil and call it "Temper"
      Now my blacksmith claims that it is not necessary to run in through the oven all over again, after the "tempering" he's done

      What do you think I should do?

      P.S. I use D3 Tool steel

      Delete
    2. Hi Varun,

      The quench in oil hardens the steel. If done correctly, a high carbon steel will be very hard, brittle and will chip easily. There will be a terrific amount of stress in the hardened steel in this state. The purpose of the tempering process is to reduce the hardness and increase the toughness of the blade.

      I would certainly recommend tempering, a minimum of two times about one hour each. The temperature you choose will dictate the final hardness. A usable knife would be in the Rockwell C 53 to 58 range. Datasheets peg this around 400°C.

      I lived in the tropics for a while and no-one had ovens. However, tempering can be done with any fire. Carefully heat the blade to a yellow/gold colour. You may heat the spine to a blue colour. This will make for a hard edge and slightly springy spine.

      Hope this helps,

      Best wishes from Canada.

      Dan

      Delete
  49. Hi,

    I am making the unit at the moment and its a great design, thank you!

    I have a question about the pillar. Since its a 1 and a half inch square tube that goes in a 2'' vertical square tube, that leaves a lot of space which cause my pillar to lean forward when pressure is apply. Did you shim your pillar too make it fit tight?

    ReplyDelete
    Replies
    1. Hi Eloi,

      When the 2" tubing has a 0.188" wall, the total gap will be 0.125". This amounts to 0.065" on each side of the pillar. I shimmed with two pieces of PET from a plastic jug. I cut strips about 1" and lubricated with graphite.

      If you have thinner wall on the 2" sections, you will need a thicker shim. Some makers weld thin sheet metal into the pillar and grind it until the fit is precise.

      Regards,

      Dan

      Delete
  50. Hi Dan,
    My computer has been acting a little funny so if you see two pretty similar messages from I'm sorry. It didn't seem like my first message was submitted. Anyway, I just recently came across your website and all I can say is "Brilliant." I have a few questions. Does the VFD Require a 24vdc power supply or could I use a 12vdc? I ask because I have a few tachometers that use 8-15vdc. Is the Fwd/Rev switch just a simple open/close switch? What are the two 4700Ohm resistors for? In your photo of the inside of your enclosure, what is the small white block in the lower left corner? I am a machinist not an electrician, sorry if these seem like pretty elementary questions. Also I am laid off from work right now. Would you have a problem with me making some of these to sell? Maybe I can make a few bucks. Thank you for all the great info on the site. I have learned a lot.

    ReplyDelete
    Replies
    1. Hi Eric,

      A 12 volt power supply would be fine. I chose a 24 volt power supply because they are common and I had one lying around.

      Yes, the FWD/REV switch is a basic single pole single throw toggle switch.

      The 4700 ohm resistors are 1) a pull-up for the hall effect IC and 2) current limiting for the LEDs. LEDs will burn up if you don't limit the current to them.

      The block in the lower left is the fuse holders and a few terminal blocks. The main power goes through the fuses there and gets distributed via the terminal blocks.

      Feel free to make some grinders! Send me a picture if you do. knives at dcknives dot com.

      Cheers!

      Dan

      Delete
  51. For those of you who have built this machine..approximately how much did you spend on materials? Also, how many hours did it take to build? Thank you kindly.

    ReplyDelete
  52. Thanks for the detailed info. What is the lower horizontal tube (frame member B) for? I assumed that it would be a receiver for the work rest, but apparently not, since you just bolted that to the bottom of the platen tube, which makes sense.

    ReplyDelete
  53. Hi Trevor,

    The lower receiver can be used to hold a work rest or light or you may wish to situate the large wheel attachment there. Initially, I made the tool rest attach to the flat platen because it was square and easy. Now I use an adjustable tool rest in the lower receiver.

    ReplyDelete
  54. Hi Dan,

    Thanks for all your work to make this an easy build. Can I send ya a few bucks? Starting to weld it up on monday. Will send some photo's as it moves along.

    Best wishes,

    Ben

    ReplyDelete
  55. Hi Ben,

    It's would be great to see your build come together.

    Thank you very much for the offer. At this time I am not accepting donations. I would recommend hitting the Walmart, then stopping in at the local food bank. That's an easy way to pay it forward. This time of year can be tough for some folks and however most of us are blessed to have a lot, some are not so fortunate.

    Peace,

    Dan

    ReplyDelete
    Replies
    1. Ok, I will do as you say. My wife and I feel the same way. And food Is always needed.

      Delete
    2. Ok, well I guess i'm not sure how to send the photo. Help! lol

      Delete
    3. Hi, Just email them it to me at this address.

      Thanks!

      Dan

      Delete
  56. Dan,

    You mentioned that you added a shim to the vertical tube. Did you have to do the same for the horizontal tool bar as well? Mine is a bit loose and tends to cant to one side when tightened. Would a plastic shim be adequate to prevent this or should I go about the task of welding a small strip of metal then grind to fit? FYI I built mine out of aluminum but otherwise your design.

    Thanks for what you have done with this site. It has been invaluable to my build.

    Peace,

    Soley

    ReplyDelete
    Replies
    1. Hi Deacon,

      I never had to add any shims to the tool arms (or the insides of the tool arm receivers). I did add some to the vertical tensioning/tracking pillar on the right and rear faces.

      If you have some weld seam inside the tool arm receivers then I can imagine it would not want to sit square. Is it possible that your lock downs are not dead center on the tool arm when you tighten them? If the arm tilts to the right (clockwise) when tightening, add a shim to the top left of the tool arm. I would think some 20 thou alum and JB weld would do the trick. Just make sure the surfaces are very clean.

      Let me know how it goes. I'd love to see a photo. I can post it over on the Gallery of Builds.

      Regards,

      Dan

      Delete
  57. Thanks for posting all this info. I built my own from the basics of your design, but the 2"x2"x.250 steel I purchased could simply not be clearanced enough to fit the 1.5"x1.5" tool arms. I went back and bought two 12"x10" .250" steel plates and six 1.5" x .250 x 10" steel bars. I drilled holes in the plates and plug welded the bars in place. Worked really well, no real clean up required. I did three potential tool holder slots (I wanted to option for a low tool rest) and the grinder works well. Thanks again for the blog, it was of great help.

    ReplyDelete
    Replies
    1. Hi Trent,

      Yes it's important to use the 0.188" wall or the 1-1/2" HSS won't go in. I am glad you came up with a solution.

      Dan

      Delete
  58. Will skate board wheels work for idlers?

    ReplyDelete
    Replies
    1. Skateboard wheels will work fine as ilder wheels. I'd recommend getting good bearings, and remember the smaller the wheel, the faster it goes and the faster its bearings will go.

      Delete
  59. Hi, I am a amateur knife maker with a low budget. I already have a motor, stepped pulleys, and wheels with a drive wheel. Do you mind telling me how much the grinder cost without those Items? I will need a tool rest, flat platen and a small wheel.
    Thanks so much, this is the most informative website yet

    ReplyDelete
    Replies
    1. Hi Sachi,

      The costs will entirely depend on how handy you are and how you source your materials. I bought the steel and welded it myself, so the cost of the frame was less than $40, add $5 for paint. I bought the wheel set which included the two 2" flat wheels for the platen. The platen was homemade from some plate and scrap angle iron, so this was about $10 for the bolts, washers and nuts. The tool rests I use are again homemade from scrap, so it's hard to put a cost those, say $10 or $15.

      Oregon Blade Maker sells the platen and wheels as as set if you wanted to go that way.

      Happy Holidays,

      Dan

      Delete
  60. Thanks! I appreciate you replying. Happy new year!

    Sachi

    ReplyDelete
  61. Hi..I bought the same pulleys from oregon blade like a bunch of others the all aluminum ones including the 4 inch Aluminum drive wheeel but the belt just sits on the spinning drive gear pulley any Suggestions? Also do you use washers between your bolt pulleys and the nuts that tighten to them? Thanks in Advance.

    ReplyDelete
    Replies
    1. Hi,

      The drive wheel needs to be set to the drive shaft (or motor shaft) with a section of key stock and the setscrew. This locks the drive wheel to the shaft.

      For the idler wheels, I used flat washers that are similar outside diameter to the inner race, but not too large as to contact the outer race of the bearings.

      Hope this helps,

      Dan

      Delete
  62. Hey Dan, one more stupid question. I have a motor in which the drive shaft is stepped down in size and not slotted. Is there a way to make this work for the drive wheel?

    Thanks!

    ReplyDelete
    Replies
    1. Usually motors will have a 5/8" or 3/4" keyed shaft. Drive wheels are bored to fit these common shaft sizes. I have made a wheel from MDF to fit a pump motor with a weird shaft. It can be done. If I could see a photo of it I could better say.

      knives @ dcknives.com

      Dan

      Delete
    2. The shaft is 3/4" for about the first inch (leaving the motor) and then it goes to .687" for the next inch and a half. I do have a pic of it, and if it's ok, I'll email it to you.

      I've been thinking I could find a shaft extension that fits the 3/4" portion and cut off the smaller portion. I haven't found one as of yet, however.



      Thanks!

      Delete
    3. I wonder if you could shim the 0.687" section up to 0.75" and fit a 3/4" bore drive wheel on the motor? You'd still need to lock it down. Do you know what the motor was originally from?

      Dan

      Delete
  63. Hi Dan,
    Just finished building my grinder following your excellent article. All works but having problems getting rid of the slop in the vertical sliding pillar even though packed out. I guess I need to pack more until it still slides but has no lateral movement.
    Thank you for sharing your ideas.
    Paul (UK)

    ReplyDelete
    Replies
    1. Hi Paul,

      I used some strips from an oil jug. They are about 0.5 mm thick HDPE and about 200 mm long. I put them on the right and rear faces of the pillar. This provides some sliding action but limits the slop.

      As long as it doesn't move when the belt is under tension you should be good.

      Dan

      Delete
  64. Hi i was wondering how did u put the spring inside the tube.just dropped it in or some extra support.sry for bad eng, hope u can understand me:=)

    ReplyDelete
    Replies
    1. The spring I used was close to the inside dimensions of the tubing. I just dropped the spring in and put the tracking pillar down to press on it. Note the bottom of the tracking pillar has a welded flat. Otherwise the spring might go inside of it.

      Dan

      Delete
  65. I have downloaded the CAD file for the wheels. Saddly the only parts in 3D are the bearings. The whole rest is only available in 2D. Could you send me a propper CAD file of the wheels?

    ReplyDelete
  66. Hi Dan, Thank you for sharing this tutorial. It is a great help, building my own grinder. But I have a problem translating a part of the text into Dutch, at least i don't understand what you mean by: "I put a backing piece of 1/4" plate behind the angle to step it away from the plate. This way the wheels and belt can be away from the plate a safe distance."
    Maybe it is possible to post some pictures that make claere what you are trying to tell?
    thank you
    regards
    Arie de Vries

    ReplyDelete
  67. I have enjoyed watching the build and plan to do my own soon. I'm a little unsure why you built the frame with the two square tube horizontal members on the frame. Since you seem to be using the top tube only to hold the support for the platen arm, is there a reason for the lower horizontal tube? Thanks.

    ReplyDelete
    Replies
    1. Hi Julian,

      I use the lower receiver for an adjustable work rest. https://dcknives.blogspot.com/p/bg272-adjustable-tool-rest.html. Others put an adjustable work light in there. In another build I have seen a sliding clamp for surface grinding against the contact wheel.

      Short answer, future proofing. ;-)

      Dan

      Delete
  68. Dan, I'm in the middle of the build and am about to mount the motor and have a question.

    If I mount the motor using 1/4 bolts as indicated wont the heads of the bolts stick out the bottom of the plate and make the bottom not sit flat on the table?

    Also is there a way to make absolutely sure you have all the wheels aligned to make the tracking work? I know the tracking assembly is there but it has to be somewhat close. Any hints or am I worrying to much? The motor has up and back adjustments but no side to side.

    Ed

    ReplyDelete
    Replies
    1. Hi Ed,

      See answer below. Sorry we got two questions as I screen them to prevent spammers from posting garbage.

      To check the wheels before running, I used a piece of construction string with a weight tied to it. I laid a straight edge on the right side of the wheels and let the string fall. The string should point in a line down to the straight edge. I did the same from the top wheel to the bottom wheel on the platen. If need be you can add a washer or two. It doesn't have to be super accurate to run fairly true. On washer here or there can compensate for construction issues, slight out of square etc.

      For me having a crowned drive wheel and a crowned tracking wheel meant having to tweak the motor until the belt was running nice and straight. Having slightly undersized mounting bolts means you can rotate the motor a little bit. If the other axis needs a tweak, adding one or two washers to the left side of the motor mount can tilt the shaft up and down.

      Hope this helps.

      Dan

      Delete
  69. Dan
    Thanks for the info and great instructions.

    I am about to mount the motor to the plate and I am not sure I understand how to do it. When I mount the motor, do the 1/4" bolts go all the way through the 1/4" plate or are they welded to the top of the plate? If I drill holes and put bolts all the way through, the heads will be on the bottom and keep the plate from sitting flat on the table. If I weld them on the heads will make the motor sit above the plate.

    Thanks in advance for the help.

    Ed

    ReplyDelete
    Replies
    1. Hi Ed,

      I used 1/4" flat head bolts and countersunk them from the bottom side. You could also tack weld the heads down to the base and slide the washer over them at that point.

      Dan

      Delete
  70. Hi, Dan-
    First, a huge Thank you! for giving your knowledge so generously. You're not only a source of information, you're also a source of inspiration and confidence.

    Your grinder design is adamant to say "use 2 in. OD square tube with 0.118 wall thickness, not 0.125 wall". Since the nesting tube is 1.5 in. OD the 0.125 wall tube makes intuitive sense... do you specify 0.188 wall to accommodate the weld seam inside the 2 in. tube?

    Thanks!

    ReplyDelete
    Replies
    1. Hi Dave,

      The HSS wall thickness is critical. 0.1875" is required to reduce the play. I recommend the seam weld be removed and made as smooth as possible. This should be done ideally before welding takes place.


      The HSS selection is based on the OD minus two wall thicknesses.

      That is: 2" - (0.1875" x 2)
      2" - 0.375" = 1.625".

      When using a 1.5" OD tool arm, this will give you 0.125" total clearance. Distributed, you will have .0625". That's 1/16" gap around the 1.5" HSS tool arm. Adding one strip of HDPE to the vertical tracking/tension pillar makes a smooth and snug fit.

      I hope this helps.

      Regards,

      Dan

      Delete
    2. I didn't follow the instructions like I should have and I need to make some "springs" to push the inner tubes to the sides of the outer tubes. I should have read closer!

      Delete
  71. Dan
    Got the grinder built and it works! Couldn't have done it without the help and instructions from your page. Keep turning out great stuff!

    I do have a question I was hoping you might be able to help with. I have a spring in the tension arm and does what it is supposed to. Where I have the grinder mounted it is kind of a pain to push down on the ball on top for belt changes. It is not because the spring is too stiff (although it is a little stiff) it is that I have a shelf right above the ball. I am trying to figure out a way to make it easier to push the tension arm down. I have room to the motor side and forward. but can't think of a way to make a mod to push the arm down. I like the way some grinders use a lever arm but that won't work for ours.

    Any suggestions?
    Ed

    ReplyDelete
    Replies
    1. Hi Ed,

      I have access to the belt side of the grinder so it's not a big effort to press down to release the belt.

      I know a guy who added a small cam like lever that pulls down on with little effort. I'll see if I can get him to provide some details and I'll post it here.

      Thanks for your input.

      Dan

      Delete
  72. Excellent build instructions. I'm curious, now that you've been using this for quite a while, how have the wheels you chose held up?

    ReplyDelete
    Replies
    1. The wheels are holding up well. Same bearings since in 2014.

      Delete
  73. One can run a groove down the center of the sq tubing, rather than removing the weld from inside the receiver. that can be an option.
    Thank you for the time and effort invested in this site!
    Kenuto O

    ReplyDelete
  74. Hi Dan

    I have made a smaller version of your grinder thank you so much for the plans
    My machine is running ok with a few issues one is chatter when touching material against the platten particularly with fine grit belts is this normal? The other is the belt moving a out 1mm left and right whilst running I think this is maybe tension or misalignment do I have any advice thank you in advance. I have the exact setting vfd do I have any advice for some of the advance settings

    Cheers
    Craig

    ReplyDelete
    Replies
    1. Hi Craig,

      The belt seams will "clack", especially with J weight belts. The flat platen is very hard compared to a contact wheel. Generally I use J (flex) belts in the slack belt mode for finishing handles and what-not. With a rubber faced contact wheel this is less of an issue as it has some "give."

      If the belt is moving laterally, there are a couple of things to check.

      1) The crown of the tracking wheel must be true. That is, not wobbling side to side when it rolls around. This can occur when people create a crown by wrapping tape around a flat wheel.

      2) The tension on the belt should be sufficient to hold the tracking. If the belt is a little loose, it doesn't always want to stay on the ridge of of the tracking wheel. Recommended 30 to 40 lbs (15 to 20 kg) spring. The belt should make a "toooong" sound like a bass guitar string when plucked.

      3) Not all belts are made equally. If trying a different belt solves the problem, then you've nailed it. In my experience after checking 1 and 2, the belt was actually not perfectly manufactured.

      For my VFD, I have set the ACCELERATION time to 5 seconds. This allows for tracking adjustment as the belt gets up to speed. I have also set the DECELERATION time to 1 second to stop the belt in a hurry if needed. The MAX FREQUENCY setting I set to 80 Hz as I have a 2 pole motor and 4600 RPM is pretty good for a top speed. A 4 pole motor, I would set the max frequency to 120 Hz. If your supply is 50 Hz, then you can up the max a little more to gain some extra speed. This always occurs at the expense of torque, but the finish that can be achieved with a fast moving belt is impressive.

      Hope this helps!

      Dan

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    2. Hi Dan
      Thank you for the fast response ☺ I bought these idle wheels and tracking wheel think they are decent quality http://m.ebay.co.uk/itm/Knife-making-x1-50mm-diameter-aluminium-tracking-wheel-for-belt-grinder-sander-/122437231775?hash=item1c81d3e49f%3Ag%3A2r8AAOSwImRYNNFy&_trkparms=pageci%253A321fdbd1-2084-11e7-b0ab-74dbd1806629%257Cparentrq%253A68e96f3315b0a60ce5b522e1ffffd781%257Ciid%253A1 http://m.ebay.co.uk/itm/Knife-making-x2-flat-profile-contact-wheels-for-belt-grinder-sander-/122437232006?hash=item1c81d3e586%3Ag%3ArBgAAOSwj85YNM0y&_trkparms=pageci%253A321fdbd1-2084-11e7-b0ab-74dbd1806629%257Cparentrq%253A68e96f3315b0a60ce5b522e1ffffd781%257Ciid%253A5 I do have some woble/play where the 40mm enters the main 50mm frame I have glued some .25mm plastic shim on to the 40mm shaft hopefully that will resolve that movement

      Belt tension probably isn't high enough struggling to get a spring here in Scotland I will keep looking maybe adapt it a bit and use an adjustable gas spring

      Thanks for all the help really appreciate it will try your suggestions one I reassemble it got it apart painting it at the minute ☺

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  75. Dan,
    Thanks very much for sharing your design and all the support materials. I have a question about the importance of the variable speed drive. It looks like the variable speed drive is going to add quite a bit to my cost. Do you feel like this is a really important feature? What about using a step pulley arrangement to give me two speeds. I don't have much experience using a small belt grinder so I don't know which are the most important design features.
    Thanks again.
    Tom

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    Replies
    1. Hi Tom,

      A stepped pulley setup will work fine. However it does come with a few trade-offs. The countershaft and pulleys can be a source of unwanted vibration and the belt and bearings will take some power away from the belt. If you have 1.5 horsepower or more you can spare the power lost. If you have 0.75 or 1 horsepower you're going to lose a fairly large percentage of your power to driving the countershaft; as much as 0.5 horsepower. (V belts are notoriously inefficient.)

      One of the main reasons for having variable speed is to slow the belt down when using small wheels.

      A fixed speed grinder will do many things well, especially if the belt is moving at 3000 surface feet per minute or more. So if you don't have a small wheel set, then go for a direct drive fixed speed setup that generates adequate belt speed.

      Regards,

      Dan

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    2. Thanks, Dan. You are very generous with your time and I appreciate it.
      Tom

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  76. Hi Dan
    Thanks for all the info on your page!
    I have built a belt grinder following your plans. I used a 3 hp single phase motor. My spring was a little longer than yours so I shortened the tracking pillar just a bit. My problem is that it throws the belt as soon as I start the motor no matter where I have the tracking wheel set. I have tried many different configurations of spacers to even moving the motor mounts to different angles to the main frame. Still nothing works. Looking for any help u might be able to offer!
    Thanks

    J from Montana

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    Replies
    1. Hi J,

      Can you take a photo of the line (looking at the belt from the front of the grinder? Email it to me at knives @ dcknives.com and I'll have a look and offer some suggestions. More often it's the motor orientation or the spring tension is lower than ideal.

      Cheers,

      Dan

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  77. Hey Dan, I'm getting ready to build my first grinder, and my question is: how critical is the thickness of the 1.5"X1.5" tubing? I am having a problem getting .250 thickness locally, and the shipping is a monster.

    Cheers!

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    Replies
    1. The wall thickness is important as you will need to drill and tap for a 1/4" bolt to hold the platen at whatever angle you set. If you use 3/16" wall you could tap it for 1/4" okay, just bear in mind not to torque down on the bolt too hard when locking the platen in place.

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  78. I've started building this because I like the simplicity of your design.

    One question/concern. There is a lot of play in between the 1.5x1.5x0.25" and 2x2x0.188" square tube. I'm guessing it's suppose to be like that and the lock-down screws keep everything pretty rigid. You mention that in that main column you ended up putting some shims to increase rigidity.

    So if drilled your 7/16 holes for the lock-down screws on the side where the weld seam is, when that is locked down and secure, essentially the 1.5x1.5 square tube will be pressing up against the opposite end of the 2x2 tube. So is there any need to remove the weld seam? Also, wouldn't it have been better to use something slightly thicker than 0.188 (3/16") on the 2x2 for a more snug fit?

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  79. Hi Danny,

    Correct. There will be approximately 0.063" all around the 1.5" pieces when they are in place. (Many make the mistake of getting 0.125" wall and that makes things very loose.

    Also Yes. You can avoid removing the weld seam on the tool arm receivers if you have your lock downs on the same side as the seam. However, I would recommend removing the weld seam from the vertical receiver, or add two bolts (same idea as the tool lockdowns) and snug them against the pillar then back them off until the pillar slides up and down easily. Have enough threads on the bolt to add a nut for locking the bolt in place once you have adjusted the play the way you want it. I'd still use some graphite powder in the vertical.

    Thanks for stopping by!

    Dan

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  80. All the DIY Belt Grinders I have seen so far have a trapezoid wheel location like here, with the lower back wheel being the powered one. (O = wheel, Q = powered wheel)
    OXXO
    XXXXXX
    OXXXXXXQ
    Is there a specific reason for not making it square like this and the higher back wheel being the powered one?
    OXXQ
    XXXX
    OXXO
    Does anyone know? I'm in the planning phase of building my own Belt Grinder and the later version would be much more convenient in my situation...

    ReplyDelete
    Replies
    1. I don't think it matters if the drive wheel is up or down on the back. The motor is heavy and add stability, so lower is better. But, in saying that, I can't see any reason why it has to be on the bottom. Interesting idea.

      Dan

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  81. Dan,

    Thanks for providing such detail on how to construct a 2X72 grinder. I am new to this and have several question:
    1. What is the screw welded to part C used for? Is this for attaching ground? Or is this welded to part D in your diagram?

    2. What is the 1/8 sched 40 pipe used for?

    3. Part J - how was the angle cut and measured on the 3x12 0.188 stock? Once again, I am a newbie trying to figure things out.

    Thanks in advance.

    ReplyDelete
    Replies
    1. Hi,
      The bolt attached at to the belt side of the vertical receiver is for attachment of an (optional) anti-static discharge brush. This brush can greatly reduce static buildup on the belt and shocks to the operator.

      The 1/8" schedule 40 pipe is for (again optional) belt release lever. It acts like a pivot point. It's better to have this on before paint then having to retrofit later.

      I cut the tracking hinge with a bandsaw. The angle is not critical and some people leave theirs as rectangles. As long as the back is cut out and it clears the pillar and can move.

      Hope this helps. If you have any more questions, just let us know.

      Dan

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    2. Dan,

      I really appreciate you getting back to me, thanks.

      Question - Is the anti-static discharge belt something I can purchase or is it easily made?

      I will attach the 1/8" pipe as suggested.

      Also, my initial hinge is not the prettiest thing but it WORKS!

      Once again, thanks for all that you do.

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  82. Hi dan,

    I live in Australia and am having issues finding steel in the sizes you mention. I don't know if I'm converting the inches to mm wrong or if Australia just makes steel to different sizes

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    Replies
    1. Hi,

      Yes, you'll have metric steel sizes. 50 mm square with a 5 mm wall should take a 38 mm piece inside with with 1 mm on each side.

      Dan

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    2. Thanks mate,

      Got the steel today, in the updated drawings you did in march you have some schedule 40 pipe welded on the end and I couldn't see where you mentioned what that piece is for

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    3. It's for attached an optional lever to assist in pushing the pillar down when releasing the belt. The retrofit version is at https://dcknives.blogspot.com/p/bg-272-belt-release-lever.html

      Best of luck!

      Dan

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  83. Hello!!

    From all the belt grinders I've seen online, this one seems to be the best and most complete one.

    However, I have a little doubt regarding the Tracking Pillar - your drawings don't show exactly where the square cuts should be when assembling with the hinge - should it be covered by the longest face of the hinge or should it be exposed from the hole side?

    Thanks!

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  84. The cut out is to accommodate the head of the tracking wheel bolt. If you use a carriage bolt a round hole works. As I couldn't find a metric carriage bolt I used a regular hex head bolt. The square cut out in the pillar proper is directly in line with the tracking adjustment bolt and is hidden behind the longer side of the hinge.

    I hope this helps.

    Dan

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