Improvipairing mah Belt Grinder

Three weeks ago one of the idler wheels on my belt grinder gave up the ghost with a screech and a puff of smoke. I was wondering why everything was overheating lately – the belts, the platens, the hweels, teh hwole heveryting. As it turns out, one of the ball bearings on one of the idler wheels was probably a bit off and when a ball bearing starts to go bad, it gets only worse from there. I have impromptu repaired the wheel but I have decided to take this opportunity to rebuild and improve my belt grinder.

The first step on that path was buying a bunch of precision-cut aluminum tubing.

© Charly, all rights reserved. Click for full size

The only downside was that the ball bearings fit too well into these tubes, they could be inserted without any effort whatsoever. And I do not have a lathe to cut grooves for internal snap rings. So I have used stainless steel foil strips as shims for one ball bearing to press it firmly into the tubing with the other ball bearing only inserted and held in place with the nut in the assembly.

© Charly, all rights reserved. Click for full size

Here you see one of the new wheels before it was assembled on the belt grinder. Aluminum tube with one firmly pressed in ball bearing, steel spacer with a piece of cork to hold it somewhat centered (I have drilled the center of the cork a lot more later on so that the spacer is really loose. The cork is there only so the spacer does not wander too far off center when assembling/disassembling), and the second ball bearing.

I have made three such wheels, and over one I have pressed another aluminum tube to increase its diameter. That one I later fixed in my drill and with the help of my impromptu repaired belt grinder I gave that wheel a barrel-like profile. Because my old tracking wheel was too getting worn and I decided to completely rebuild the spanning arm.

© Charly, all rights reserved. Click for full size

Here you can see the right side of the spanning arm with the new spaning wheel. I won’t go into technimicical details. Here you have a second picture of the left side, it should be worth a thowsand words.

© Charly, all rights reserved. Click for full size

This is in part made from new materials. The downside of this assembly is that I had to weld a 30 mm M10 nut onto the arm. Which was not easy. To say that I suck at welding would be to grossly and immodestly overstate my abilities. When I die, the average welding ability of humanity will probably go ever so slightly up. But after a few botched attempts, I have managed to make welds that at least hold in place, even when they look completely craparooni.

The tracking wheel is on an M10 thread rod and thus can be moved left-right with the help of the upper handle. That is necessary to at least somewhat center the belt on the tracking wheel to avoid asymmetric wear of its surface, My previous assembly did not allow for this and as a result, the wheel got really worn on the left side only.

The second screw under that allows for slightly tilting the spanning arm left-right. That moves the belt slightly from left to right, allowing it to center on the platen. This was starting to be difficult with my previous arm, in part because the assembly was a bit too sensitive (short pivot point) and in part due to the asymmetrical wear on the tracking wheel.

I have used the improved belt grinder for a few hours and it seems to work well. When the current batch of knives is in the tumbler, I will coat the wheels with PVC plastic and perhaps start making some other attachments for the belt grinder.



  1. johnson catman says

    Charly: Have you had formal engineering training? Because I think even Scotty (Montgomery Scott) would be impressed with your making and remaking things to suit your purpose.

  2. says

    *Every* new welder sucks. :-) I have probably forgotten most of it, but we were taught the basics of oxy-/acetylene, stick and mig welding in engineering school. Very handy to have someone around to explain what you’re doing wrong and how to improve.

  3. says

    Thank you for the kind comments.
    @johnson catman, nope I have no formal engineering training. All my formal training is mentioned in my introductory post -click-. But in my previous job I have worked with a lot of engineers and many of them assumed that I am an engineer too until I told them otherwise -- some even for years. I guess that playing extensively with our equivalents of Lego and Meccano (as well as multiple other types of building blocks) and making models from PS and paper as a kid has had its benefits.
    I have even managed to make an invention in my previous job, but the patenting process went to nowhere and the thing probably will never see the light of day (90% of patents are hoarded by big companies not for the purpose of making them but for the purpose of preventing others making them).

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