Thread: Build your own grinder

that grinder that I built out of an old treadmill and some pop cans and scrap aluminum is still working really well. I don't really hog on it that much though, as ive got my other 2 home built grinders with normal motors for that.

I did just order a 14" contact wheel from ameribrade that is really nice, especially for the price. I think it was only about $200, and they have lots of other sizes plus flat plattens. and at the prices they charge, I'm not sure I would bother casting the wheels and then machining them on my old southbend anymore unless I needed a custom size or something.

oh, and I really think that this is what treadmills are made for, as it sure beats running on them :}

Those wheels look a lot like skateboard wheels. Just a thought.

Originally Posted by Gasman

Those wheels look a lot like skateboard wheels. Just a thought.

There's a very good reason for that: they are long board wheels. They will wear eventually end need to be replaced, but for now they should work fine.

I used a couple skateboard wheels on some of the first grinders I built {ive only built half a dozen of them} and they worked ok. on a slower machine they would probably last a lot longer. one thing to think about when using them is that they are so small, so when you run the belt fast, those little bearings are just humming. the larger diameter wheels {except the drive wheel} that you use in your build the slower the bearings run and the quieter your grinder will be.

Unfortunately a bad case of the wobbles and some tracking issues have had me scratching my head recently, and keeping me from playing with my new toy,

I suspect I have two issues:
1) motor and therefore drive wheel aren't perfectly aligned with the rest of the grinder. The belt wants to wander in towards the motor, and I end up with the belt rubbing against the wall of electrical tape I added to the drive wheel to prevent belts from getting pulled right against the grinder body.
2) the pipe I welded to the treadmill motor's flywheel isn't perfectly centered. It's awfully damn close, but not 100%. This gave a worrying level of wobble. I beefed up my gas strut/shock to increase tension, and that helped. But a (slightly) wobbly drive remains a (slightly) wobbly drive.

So my plans are:
a) double/triple/quadruple check the drive's alignment with the rest of the system
b) try adding a bit of a crown to the drive wheel - I've seen on some forums that a slight masking tape crown can work wonders for some
c) before adding the crown, try building a bit of a foundation to fill in the low parts of the drive wheel.

Any other suggestions? If this doesn't work I think I'll bit the bullet and get a piece of round aluminium machined to fit directly to the motor's shaft. Man, I wish I had a metal lathe...

Luckily, I'm now sure the motor as enough oomph to power the thing. But until I get the tracking/wobble issues sorted, I'm really not comfortable running it at anything approaching full power. Gets a bit concerning as the RPMs get up there.

Oh, and for anyone building with off the shelf parts, here's a tip: if you don't have a lock nut attaching your wheels, some thread lock is a good idea. I had a double-nut on mine, but after two of the nuts went flying out sideways as if shot from a cannon, I have reinforced it with thread lock, and will pick up some lock nuts after work today. That sure got my attention: I really wasn't expecting bits to fly off horizontally.

Well, I'll be damned... the masking tape did the trick. It's not perfect yet, but it's *finally* a functioning grinder.

It's funny how the 'crown' on the wheels makes them track.
I made wheels for specialty band saws decades ago. Machined the cast aluminum wheels set-up with tapered adjustable hubs. Sent-off to have rubber put around them and a process to machine the rubber in a humped manner. As the aligned wheels were running straight and true, the band would run right on top and stay there. Of course there were carbide guides close to the material.
Still....Goes against what you might think..

Originally Posted by sharptonn

It's funny how the 'crown' on the wheels makes them track.
I made wheels for specialty band saws decades ago. Machined the cast aluminum wheels set-up with tapered adjustable hubs. Sent-off to have rubber put around them and a process to machine the rubber in a humped manner. As the aligned wheels were running straight and true, the band would run right on top and stay there. Of course there were carbide guides close to the material.
Still....Goes against what you might think..

You should start doing this again for the 2x72 grinder market! Right now there's basically one company that seems to dominate the field. I've heard nothing but good things about them but couldn't afford their wheels at this time which is why I went the home-brew route. I'd definitely welcome some competition in that market.

I agree about the crowns though. They seem to be completely counter-intuitive.

one thing to keep in mind about the tape or built in crown on your tracking wheel is that if you overdo it, as I too much crown, sure it will make it track great, but it will also stretch out the center of your belts. just something to keep in mind.

Plus on very coarse belts, it can crack the surface of the belts.
That's also why you should never run a new 36 grit belt over a 3/4" roller. The surface cracks and the belt degrades pretty quickly.