Surface grinder wheel counterbalance t

I recently restored a early fifties vintage Ried grinder and am pleased at it’s performance. I purchased two wheel adapters and wheels. The well used wheels that came with it were fine but the new 7 inch diameter wheels caused some vibration. Not wanting to spend $300+ on balance adapters I found making these counterbalances worked very well.Attachment 43918
Attachment 43919
Making two cups, one nesting in the other with one half of the flange removed on each.
Attachment 43920
On the balance fixtureAttachment 43921Attachment 43922

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I've found grinding wheels on eBay, most of them are severely out of balance (I think they fail some sort of receiving inspection). But I've gotten lucky to purchase some that produce acceptable surface finish. I've tried different balancing methods, and purchased a wheel balancer that's the type with that use 4, 6 inch disks on low friction ball bearings, but I don't see the friction low enough to get a wheel balanced to not create ripples in the surface.

I've tried this method from this web sight;
https://conradhoffman.com/grindbalance.htm

Problem I have was measuring the 60Hz vibration (motors running 2 pole at 60Hz power run close to 3600RPM, hence 60Hz vibration), I was using my oscilloscope in Fourier transform mode (FFT), but the software was limited (didn't want to produced good plots at 60Hz) and buggy (Rigol DS1054Z). There's just so many other harmonics (and 60Hz noise from the radiated power system, and electronic amplifiers pick that up as well). It sorta worked but was very time consuming. I purchased an accelerometer off eBay, also tried piezo speaker disks. I keep any grinders away from the machine tools, as the grit and dust is nasty. And using electronic gear, makes me cringe (in this environment) as well and has too much setup, and tear down.

I've seen purpose built fixtures that use level 'blades' of the same idea as your simple use of precision square blocks.

I'll have to make some balancing washers like yours.

Thanks for some different ideas on fixing nasty wheel balance.

Hi, I use small diameter drill rod on the blocks to further reduce rolling friction. I believe this method has less friction because it eliminates(almost) bearing friction. It is very sensitive so getting it perfect takes patience.

Quote:

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Originally Posted by Eaglewood

<snip>
Making two cups, one nesting in the other with one half of the flange removed on each.
Attachment 43920
<snip>

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I'm trying to understand how you fabricated these washers with the weight lobe. From the photo I quoted, it appears the radius of the masses are different. How do you keep this in static balance if their centers are exactly 180 degrees apart. Would not the smaller radius require extra thickness of material to stay balanced?

Clearly it's working for you, but I'm missing something in the implementation.

I do like that you used round bar for the rails, that seems to be so easy to chop off a piece from drill rod, which I stock in smaller sizes.

I carefully calculated the difference in masses and sized the flanges accordingly. I made a 3D model in Fusion 360 and found that the cg was almost perfectly on center radially. It was off .002-.003. Off coarse machining tolerance weighs in but I just balanced a 7x1 recessed wheel that was way out of balance and it runs fine.
I found that if I put the wheel on the balance fixture without the weights and mark the heavy point then add the weights perpendicular to that cl it is easier to rotate the weight mass away from the heavy side.

Quote:

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Originally Posted by Eaglewood

I carefully calculated the difference in masses and sized the flanges accordingly. I made a 3D model in Fusion 360 and found that the cg was almost perfectly on center radially. It was off .002-.003. Off coarse machining tolerance weighs in but I just balanced a 7x1 recessed wheel that was way out of balance and it runs fine.
I found that if I put the wheel on the balance fixture without the weights and mark the heavy point then add the weights perpendicular to that cl it is easier to rotate the weight mass away from the heavy side.

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That had to take some time to machine them from stock, then cut away the half flange material from each and verify/calibrate the material removed from each produced static balance. The commercial hubs are very pricey that have the 3 movable weights in them. So this drives the DIY solution of making something that works. I did see a solution where a dynamic set of ball bearings were placed between two disks with a groove machined for the balls so they would dynamically balance when it was spun up. But that needed much more hub length for the thickness of the disks.

Yes I chose my rendition due to price and space available on the hub.