auto-balancing bench grinder arbors

**mattthemuppet** · Aug 18, 2016, 05:36 PM

could be, although centripetal force (or lack of it) keeps them in place as far as I can tell once the grinder is up to speed. They only roll around on start up and just before the grinder finishes slowing down to a stop. I tried grease and it didn't let them move at all. I don't think oil would hurt but I don't think it's necessary either, plus the downsides of sealing it in as you said.

I'm getting some 3/16 balls tomorrow, just can't stop needing to itch that scratch and see if I can fully balance the wire wheel.

**C-Bag** · Aug 18, 2016, 08:56 PM

You go Matt. I KNOW the itch, when you are so close but not there. Some folks are with ok with 75% I'm too OCD to let it go. All of this is kinda counterintuitive for me.

It might be one of those things where less/larger bearings would work. Dunno. I'm somewhat skeptical of any kind of oil in there too.
Glad you've decided to work all the way through.

**Bloy** · Aug 19, 2016, 10:00 AM

Thanks for the article.

**mattthemuppet** · Sep 18, 2016, 01:19 PM

you're welcome!

quick update. Finally got some time to recut the groove for 3/16 balls and I made it wide enough that the balls could stack in one spot (in a zig zag pattern). Filled the groove a 1/3 full, spun it up without and then with the wire wheel. Still some vibration and no detectable difference from the 5/32 balls, but a noticeable difference from no balls. That'll have to do, works well and what vibration there is doesn't affect the finish I get from the grinding wheel.

My guess is that it's just a crappy wire wheel - got it from Lowes and the hub is visibly out of round with respect to the center hole. I'll keep my ears and eyes open for a better one at some point.

**C-Bag** · Sep 18, 2016, 01:54 PM

Originally Posted by mattthemuppet

you're welcome!

quick update. Finally got some time to recut the groove for 3/16 balls and I made it wide enough that the balls could stack in one spot (in a zig zag pattern). Filled the groove a 1/3 full, spun it up without and then with the wire wheel. Still some vibration and no detectable difference from the 5/32 balls, but a noticeable difference from no balls. That'll have to do, works well and what vibration there is doesn't affect the finish I get from the grinding wheel.

My guess is that it's just a crappy wire wheel - got it from Lowes and the hub is visibly out of round with respect to the center hole. I'll keep my ears and eyes open for a better one at some point.

Matthemuppet, have you seen the Oneway Wheel balancer? I ended up going that route because I had spent hours already on this silly 8" grinder of mine and it was still scaring me to death. I think it's probably and easy thing to copy and make yourself especially the balancer jig. My fine grit wheel was a real challenge and it's got it running smooth, something I never thought I'd accomplish. This is not an auto balancer, but it sure works good. I did a little write up in the tools and tricks section of HMT.

**mattthemuppet** · Sep 18, 2016, 02:30 PM

thanks for the reminder c-bag, I looked up your post and enjoyed the read. Much appreciated. It would be an interesting option for sure and one I'll keep in mind for the future. Right now though I'm itching to get on with other projects

I need to finish up a bearing remover and some spacers for my bike bottom bracket bearings.

**C-Bag** · Sep 18, 2016, 03:44 PM

Yup, know the feeling, that's why I opted for the Oneway. Just didn't have time and had to get 'er done.

Good luckmwithmthe nearing remover and bottom bracket spacer.

**mattthemuppet** · Sep 20, 2016, 10:09 PM

thanks, nearly finished it, just have to part off the bearing pusher. Also made a couple of spacers by trepanning into the face of the slug at the desired ID, turning down the OD and then parting off. After that all I had to do was turn the nub down to the ID of the bearing. I was rather pleased with myself about that

**Scrounga** · Jan 30, 2020, 05:02 PM

Good idea but I just balanced the wire wheels. I made a simple jig and use short self tappers to counter balance a bit like the way they used to do car wheels.
Stopped nearly all the vibration which used to drive me crazy. Nice work you have done there. Cheers Stuart, Australia.

**tonyfoale** · Jan 31, 2020, 02:39 AM

I have not read all the follow up posts here so I hope that I am not being repetitious.
Decades back I had access to mercury and I made similar devices using mercury instead of balls. Years later after some house moves , new grinders and the loss of the mercury source I tried the same with water. That only worked when I made them with impractically large diameters.
This theme has prompted me to revisit this. A month or two ago I wanted some hard and heavy balls and I bought a box of 1/4" tungsten carbide balls. They were not expensive and should be better for this application. In fact when I finish writing this I'll be in the workshop making one from a Delrin case for low friction and carbide balls for their mass. Also their greater mass to size ratio should reduce any sticking problems. Lead balls might work but I doubt that they would retain their shape over time and start sticking. Delrin might suffer a similar fate over time from brinelling by the carbide balls. If so then I will change to metal cases.

PS. I'll do this with a square groove about 1 mm wider than the ball diameter. The balls will only contact the holder on the outer part of the groove when in use so plenty of clearance on the inner wall will do no harm unless it is so big that the balls jam under one another.
I'll report back.

PPS. I have already changed my mind. I will go for steel cases and forget the Delrin.