Abrasive impregnated nylon fiber

Have you considered trying to pressurize bearings to keep stuff out? I built a semiautomatic bead blasting machine for a former employer. The part to be cleaned was mounted on a mandrel and inserted into a tube that ran in a Teflon block. Flanges top and bottom had felt seals and the block was under about 5psi pressure. A small gear motor rotated the tube. Abrasive nozzles were mounted to the end of shafts passing through polymer sleeve bearings. I used mountain bike fork boots to seal the shafts inside the chamber, and the boots were also lightly pressurized. There were two chambers, one side runs aluminum oxide, the other runs glass beads. This machine has cleaned several hundred parts a week for some 6 years now with no maintenance to the moving parts.

Depending upon the design of the machines you build, it might prove challenging to design everything so it can be pressurized, but the idea certainly works.

Jon

These shafts were reciprocated as the part was turning, to provide full coverage. That's why the pressurized boots on the shafts...

Jon

Jon has some mighty good thoughts, I was thinking about going low-tech and using babbit bearings that were easy to get to so you could melt 'em out and repour quick. If you can keep the bearings at the ends of the shafts you could also make the shaft's bearing surface replaceable.

John

I have a half hundred 1/2" ones and some 1.5" nylon cup brushes. I can send you a couple for investigation.

Gunner

This gives me an idea - hydrostatic bearings. If pressurized fluid is fed to the center of a plain plastic bearing running on a stainless steel shaft, the pressure will keep the shaft floating, and the outward flow will prevent the entry of grit into the bearing space, especially if simple shaft seals are provided. It's best to have a groove in the bearing to carry the fluid all around the shaft, to ensure even flow and pressure. Hydrostatic bearings work at any speed, right down to zero. But you have to remember to turn the pressure on before starting the machine.

Use water so it doesn't make a mess and contaminate the product.

The required pressure will be in the hundreds to maybe a thousand psi, depending on bearing area and needed forces. Plain old tap water will do. One could adapt a pressure washer to be the pump.

Joe

Thanks Gunner but I make end brushes and 3" to 6" wheels so I have stuff to play with, but tell me about using them...the god and the bad, what applications do they shine. (pun intended)

Ive only seen them used for surface finishing (polishing) and very light deburring. They are not particularly common in machine shops that Ive visited, shrug. Seem to work pretty good on Stainless steel for fine polishing, which is about all Ive done with mine, in a drill press. I did use one of the small ones to jewel a piece of steel, but it was pretty unimpressive compared to a dowel and fine polishing compound. They are reputed to do a decent job of deburring without making dimensional changes to the parent features.

perhaps these might help?

Gunner

In addition to Gunner's response:

I recently used one of these in the form of a small dia pad, probably

3M "Roll-Lock", in a die grinder to pretty up some aluminum boatlift parts after welding.

I'd first tried wire brush (too slow), and rotary wire brush (too aggressive). The Skotchbrite pad worked beautifully, and right now!

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