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Old December 11, 2018, 09:11 AM   #1
Geezerbiker
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Bench moutned polishing wheel viberation

I bought a 3/4HP bench grinder with a polishing wheel on one side from Harbor Freight to do some gun polishing. However it shakes like crazy and I wasn't able to get much done because I though it was going to shake everything off my bench.

Could it be that the wheel is out of balance? I took off the grind stone on the other side but it didn't make any difference. Is this something that might improve with wear?

When I took off the polishing wheel, the hole looked centered but I didn't think to run the motor unloaded at the time... I'll try that tomorrow.

Tony
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Old December 11, 2018, 10:42 AM   #2
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Something is out of balance, for sure. I have owned cheap grinding and polishing wheels long ago and finally given up and saved my pennies to buy Baldor. These days, though, you can do your own balancing more easily than was once the case. Here's a pretty good method using a smart phone's inertial sensors.
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Old December 11, 2018, 10:51 AM   #3
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Harbor Freight tools are a crap shoot. You can try to fix the problem but you'll probably be happier just getting Jet or Baldor that is designed for buffing and polishing. That might be tough to justify if you just have one gun to polish so take the one you have back and get a replacement. Sooner or later you'll get one that works right.
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Old December 11, 2018, 02:02 PM   #4
Bill DeShivs
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The motor is probably fine. Cheap, off-center buffs are the problem.
Buy quality buffs from jewelry supply houses or specialty suppliers.
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Old December 11, 2018, 04:34 PM   #5
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Quote:
Buy quality buffs from jewelry supply houses or specialty suppliers.
Or just true up the ones you have.
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Old December 11, 2018, 04:56 PM   #6
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I wonder if you could slow it down. Off balance I'm sure but the faster you spin it the worse its going to be. Good luck.
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Old December 11, 2018, 06:30 PM   #7
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If the hole in the buff is not snug on the shaft get a bushing to fit before you take anything apart. It doesn't take much to cause an out of balance condition. Plastic is fine for a bushing.

My electric dryer was shaking pretty good and the boss was complaining. After checking out all the mechanical stuff I went to the squirrel cage. Some of the vanes had a pretty good lint build up, some not. Vacuumed and brushed all the vanes and back in business.
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Old December 11, 2018, 08:37 PM   #8
Bill DeShivs
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It's very difficult to true up a cotton buffing wheel.
Most bench grinders run at 3500+- RPM, which is really too fast for polishing.
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Old December 18, 2018, 03:29 PM   #9
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I finally got back to it this morning. I took the polishing wheel off and the motor was nearly vibration free. I put the wheel back on and I could see that there was only one small place where the polishing compound was built up. I used a hammer handle as a gauge and I could see that the wheel is 3/16" out of round. I'm wondering if I could use a chisel and cut the wheel down like on a wood lathe...

Tony
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Old December 18, 2018, 08:34 PM   #10
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If you're polishing guns a common buff is exactly the wrong thing to use.
The soft, thin buffs are made to polish jewelry, not guns.

Using cotton or muslin buffs is how sharp edges get rounded off, ripples are left in the flats, screw holes get dished out, and stamps are thinned out.
Nothing looks worse then a gun ruined by a polisher using the wrong equipment.

The correct polishing heads are either HARD felt or metal wheels.
They need to be LARGE diameter, at least 10 inches or more, and depending on the part being polished, they need to be stacked at least 8 inches wide.
The larger and wider the polishing head is, the easier it is to keep surfaces uniform and unchanged from the factory surface.

Also, professionals have small specialty polishing heads for key areas like inside a trigger guard.

Colt was always famous for the quality of their polishing. They used large diameter wood wheels covered with walrus leather.
Later they went to metal wheels covered with abrasive belts.

1940's Colt polishing wheels....



Later Colt metal wheels.



The NRA just put up a video about some of Colt's new guns and what they plan for the future.
In the video are scenes showing Colt's current polishing heads. Note how large in diameter and how wide they are.

https://www.americanrifleman.org/art...CENSORED-=1218
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Old December 19, 2018, 01:31 PM   #11
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Love it, industrial buffing!
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Old December 19, 2018, 01:55 PM   #12
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LineStretcher has it right. You buy from Harbor Freight and you have no way of knowing if it will last 5 minutes (if that long) or 5 years. I have learned to be very careful in my tool buying from Harbor Freight (which has included some items that have proven themselves to be quite serviceable despite a very low price) .
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Old December 21, 2018, 09:15 AM   #13
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Thank you Dfariswheel for sharing those images. Like shoe brushes, the bigger the better.
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Old December 21, 2018, 02:51 PM   #14
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Geezerbiker,

If it is 3/16 out of round, you can use a drafting compass to find its center and then drill or Dremel out the extra material out until you have an oversized but centered hole. Find some tubing or pipe that has a wall that thick and that fits over your shaft closely (you may need to add some shim stock to get a close fit). PVC tubing should be fine. Cut the pipe a little shorter than the thickness of the wheel so it doesn't interfere with the washers that clamp it down. Stick the pipe in the middle.
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Old December 22, 2018, 03:36 AM   #15
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I got tired of screwing with the wheel and tossed it. I bought a couple 2" wide 8" wool felt wheels off Amazon for a bit over 20 bucks each.

Harbor Freight has a pretty good guaranty and they really stand behind their stuff. I'm not thrilled about the buffing wheel but I know if the motor burns out, they'll replace it. Some of their stuff is absolutely amazing for what it costs. I bought a 1/4" drive flex head ratchet there that is as good as any I've ever used. Some of their stuff is crap but things that would hurt their bottom line on returns is better quality.

I'd love to have a high dollar polishing set up but I only have one gun and some small bits to polish and maybe some motorcycle parts latter on...

About 30 some years back, I polished a lot of BSA and Norton parts on a similar set up... If the RPM is too high, I might set up a pulley reduction set up if I find it necessary.

Tony
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