A Woodworker Builds a Belt Grinder

Roger T

Roger T

Well-Known Member
After seeing how useful and versatile the belt grinders are in Bruce Bump’s shop, I knew I “needed” one too. Ready-made was way out of my budget, so I set out to see what I could build. I wanted a variable-speed motor, so after some research I purchased a 2HP 3-phase motor that turned at 1725 rpm. With a variable-frequency controller I can set it to run at any speed I wish with just the turn of a dial. I am a woodworker, I have a shop full of wood scraps, but I don’t have a place to cut and weld steel. Here is what I came up with, I hope it may be useful to someone else who’s interested in putting a grinder together.

I took a 4” square block of soft maple inserted 4 hanger bolts and mounted pillow blocks and a 12” x ¾” shaft to carry a 10” contact wheel. The motor has a 5” drive wheel.
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I traced the wheel and belt configuration on a piece of masonite and built this support for my idler/tracking wheel from three layers of ¾” Baltic birch plywood. The recess is for the gas spring that will tension the belt and the cutout fits over the pillow block.
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The tracking adjustment consists of this gate hinge and a fine-threaded 5/16 bolt threaded through a steel plate inset in the arm to press against the hinge to change the angle of the 4” idler wheel.
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More to follow.
 
Further progress

These show the arm that holds the tracking wheel. It’s a piece of oak pivoting on a ½” bolt that runs through a pair of metal brackets bolted to the support.

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This 20 lb. gas spring tensions the belt.

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I assembled it and temporarily wired it to test run it. The front section of belt is 15 degrees from vertical for sharpening use. I set up the variable-frequency drive for a maximum of 120HZ (3450RPM)

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It Works! Surprisingly quiet and smooth - the cooling fan in the variable-frequency drive makes more noise than the motor and sander. Now to take it apart, paint it and assemble it for good.
 
Nearly complete

Here’s the finished grinder after painting and cleaning up the wiring. I still need to add a flat platen, devise a tool rest and build a stand for it. I’ll post pictures of those as I get them done.

The three holes are for attaching the flat platen.
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I made a wooden cover over the exposed shaft so fingers can't get pinched.
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Thanks for viewing, I'm happy to answer any questions.
 
Now that is impressive!! I'd not even considered using wood to build the 2X72 grinder.

Ken H>
 
I've seen a few wood frame grinders before but this one is way out in a league of its own. It came out great Roger. How does that hydraulic strut work? Is it about the right amount of tension?
 
Roger,
Exellent design and fabrication. If I may suggest, when you make a flat platen, have one of both of the wheels be hard rubber covered so you can do radius or just contact grind against them.

I found that aluminum wheels can break belts when you contact grind against them also they slip more.

My hardcore products grinder runs a 5" 90 durometer wheel on the bottom of the flat platen and an 2" on the top.
those two sizes are are very helpful in contouring the profile of my blades.
 
Bruce Bump said:
I've seen a few wood frame grinders before but this one is way out in a league of its own. It came out great Roger. How does that hydraulic strut work? Is it about the right amount of tension?
Click to expand...

Thanks everyone for the kind words. This has been a fun project. I guessed at the tension by holding belt at about the angle it would have as it passed over the tracking wheel and set a pair of my wife's 10# dumbbells on it (no comment on her 180# dumbbell :3: ). It seemed about right, so I ordered the 20# strut from McMaster-Carr. So far, it does seem to work just fine.
 
rhinoknives said:
Roger,
Exellent design and fabrication. If I may suggest, when you make a flat platen, have one of both of the wheels be hard rubber covered so you can do radius or just contact grind against them.

I found that aluminum wheels can break belts when you contact grind against them also they slip more.

My hardcore products grinder runs a 5" 90 durometer wheel on the bottom of the flat platen and an 2" on the top.
those two sizes are are very helpful in contouring the profile of my blades.
Click to expand...

Thanks, Laurence, now you've got my wheels turning on how to make that work. I'd have to slip off the 10" wheel and bolt on the platen assembly in its place.
 
Platen

Here are a couple of pictures of the flat platen attachment.

I epoxied a 6 x 2 x 3/16 steel bar to a wood block shaped to fit over the contact wheel.
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The front portion can be removed if I need to make a change. The wooden spacer is temporary until I get the ceramic platen cemented in place on top of the steel.
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Roger,
That looks great! Perhaps you can make a small wheel attachment that will go on there when the need arises?
3/4" is the most common and I also use my a 1" 2" and I use a 3/8" for choil cut outs by the ricassio on a blade.

You are going to be another one of us grinding fools now!
LOL:35::biggrin:
 
Roger

You definitely have great skills to build something like that.

This is not a criticism but as a suggestion - you may want to have the top two screws holding the platen on up higher. It will give you more work room between the bottom screw hole and the top two screw holes. You do not want to drag a blade across those if it can be prevented.

Otherwise, I think your design and execution look brilliant.

DeMo
 
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