Machining belt-grinder wheels

[jwmelvin]

I made some progress tonight. Cut a couple retaining-ring grooves in the first ID (one of the two straight rollers). Also bored and finished tapered OD of the tracking roller (I had enough stock that I don’t have to mount it on a mandrel to finish the OD).

Grooved ID straight roller:

Bored and crowned tracking roller:

Seems to be going okay. I was more careful on the second bore and it seems to be a better fit than the first one I did.

I don’t find much time to work on it but will continue to chip away...

 

[mikey]

That's a fair bit of overhang on a big work piece with not a lot of jaw grabbing it. You might consider using a live center to do your OD turning, then remove it and slow down to do the boring.

 

[BFHammer]

Looking good. Turning the OD in the 3 jaw for the tracking wheel should be ok since it will be adjustable. On you other (non-crowned) wheels I would suggest using an arbor to turn the OD so that it will be concentric to the bore. That way you want have an "unwanted tracking" on your other wheels.

 

[jwmelvin]

Thank you both. I figured since my OD cuts were super light, the piece seemed sufficiently held; your point about using a center, however, is well taken.

The tapered OD was turned in the same setup as the bore ID so should be concentric, right? I do plan to make an arbor for the rollers where I don’t have enough stock to grip while turning a sufficient amount of the OD.

The drive roller seems like it will be interesting as it will start to expose the size limitation of my lathe. I need to think about it’s mounting to the treadmill motor too. I may consider an intermediate belt between them to reduce load on the motor bearings.

 

[jwmelvin]

Making an arbor worked out okay for my rollers, so far. I was able to finish the OD of the two idlers using a simple arbor and an end cap I 3d printed to press the roller on the arbor’s shoulder with a center:

Really that worked for the roller with the loosest fit but the other two were tight on the arbor. Heating the roller allowed it to go on the arbor and come back off (differential expansion of aluminum vs. steel); the tracking roller was tight enough to leave proud of the end of the arbor, so I could finish its width. The end-cap setup, however, doesn’t let me face the two idler rollers, which I’d like to do for width and finish. I suppose that I may need to make my arbor an expanding one after all.

Alternatively, is there a good way to hold the OD of the noncrowned rollers without damaging it? Even in the 3-jaw, I could face them to length. Can I just put some think paper between the jaws and the roller surface? I suppose I should have done the length first then the OD.

Though I could use the wheels as they currently sit:

I’m working on the drive roller, which will need a key way as I bought a 2hp 3-phase TEFC to use instead of the treadmill motor. I was considering a broach set but since it’s a single part I may try to do it with the lathe carriage once I bore the hole.

Any advice on whether/how to remove some material from the drive wheel to shorten the length of the key way? I like the idea of a long bore fit to the motor shaft but I don’t need that long of a key way. Maybe drilling a hole aligned with the key, part way through the roller’s width? The roller will get cut from the piece of stock I am working with, such that I could finish the OD in the current setup. I’ll have the same issue of facing it as I have with the idler rollers though.

My progress is slow but I enjoy the time I spend on it. I think I’m getting better with the 4-jaw...

 

[jwmelvin]

Cutting down my 6” diameter stock was a bit of a project. I used a parting tool until my lathe no longer wanted any part of it. it seemed to bind and the whole operation was suboptimal so I switched to the band saw. That required making a new jaw to hold the piece:

Cutting from several directions and then a bit by hand eventually removed the ~3/4” of material.

After facing the cut side, I decided to try cutting a key way without buying a broach, (I forgot to bid on a used set and haven’t seen any attractive ones since). Thus I had to prototype a spindle lock:

The final version needs to be sturdier but it did the trick.

Then I needed a key-way tool, but grinding required some sort of tool rest, so I started a prototype:

I started with a boring-bar-looking tool that the guy gave me when I bought my lathe and ended with this:

...and had at it. It seemed to work pretty well:

I overshot the drive-wheel bore about 0.0015” so I’m considering a radial pattern of axial screws in the face of the wheel, close to the bore, with a conical interference so I can true the wheel once mounted. Maybe even one such pattern on each face;or as through-bolted compressions to squeeze the bore at each face. Mostly as a design exercise, as I think the belt will be fine with a couple mils runout. The adjustable clamping mechanism would take the place of a set screw.