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Balancing and dressing plate-mounted grinding wheels

rimcanyon

Diamond
Joined
Sep 28, 2002
Location
Salinas, CA USA
I installed a CGW aluminum oxide wheel on my carbide tool grinder so I can use it for grinding HSS. The wheel is the type which is mounted to a steel plate with four holes.

CGW-WHEEL.jpg

The wheel is slightly out of balance. Enough to feel some vibration when the grinder is running. How do you balance a wheel like this? I tried dressing both the outside and inside surfaces as well as the face, and it helped the balance, but I would sure like to get it better. When the wheel coasts to a stop, it never stops in the same place, so it doesn't help locate the heavy spot. I also checked the four screws for weight and they match within 2 grams. I used to have a diamond wheel on the grinder and there was no vibration. The 3-phase motor is nice and quiet and runs on about a minute after being shut down.
 
Q, The wheel center hole is not washed out way large?
Q,Using flat head machine screws so the screws ?
Q,The machine seem to run smooth with not having a wheel?

This would be a Hack method if the wheel is centering pretty tight to spindle center
Set your table flat and C Clamp a couple paralells to your table to hole the wheel on one place with these to the left of your wheel.
Glue or double back tape two hex nuts to your table at 8:00 and 10:00 so the left wheel back sets on those nuts, with your wheel's 3:00 place setting on a gram weight scale to find the heavy area. My gram weight scale is 5/8" tall so i would use nuts tha tall. Use a old carbid drill and diill some balance hole in the wheel OD.

Likely you could set some sand to get a rought idea of how much wheel to drill away.from the OD.

Another Idea if the wheel may be coolant logged is to soak the wheel in a mix of washing soda and water a few days (not baking soda but Washing soda).

*Guess I would try the washing soda bath first

 
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Try adding washers under the screw heads. Grind the washers to shave a little weight to fine tune. There is a spreadsheet from @Conrad Hoffman floating around that describes a trial and error method that works well to balance - you may be able to use a smart phone with accelerometers built in as a vibrometer. There's also an app I use that does the same as the spreadsheet, it's called "Adash Balancer." It might ask you to add weight between the holes, you can usually split it and bias between the holes based on their angle to the recommended weight location to get the same effect.
 
Try adding washers under the screw heads. Grind the washers to shave a little weight to fine tune. There is a spreadsheet from @Conrad Hoffman floating around that describes a trial and error method that works well to balance - you may be able to use a smart phone with accelerometers built in as a vibrometer. There's also an app I use that does the same as the spreadsheet, it's called "Adash Balancer."
How well does the Adash balancer app actually work? I've got a lathe where the previous owner swapped out the spindle bearings without marking all the positions of screws and washer packs and I would like to try and balance it.
 
How well does the Adash balancer app actually work? I've got a lathe where the previous owner swapped out the spindle bearings without marking all the positions of screws and washer packs and I would like to try and balance it.

Works great for me when I've used it. I have a small Tektronix balancer demo kit that I initially used to try it out, the Adash balancer app gets things pretty darn good on that. It basically just has you run through the same stuff that Conrad's spreadsheet mentions, in a more automated form and does the calculations for where to add/subtract weight and how much. I actually have accelerometers and all that stuff to do it manually, but the app actually works well enough for me most of the time.
 
Works great for me when I've used it. I have a small Tektronix balancer demo kit that I initially used to try it out, the Adash balancer app gets things pretty darn good on that. It basically just has you run through the same stuff that Conrad's spreadsheet mentions, in a more automated form and does the calculations for where to add/subtract weight and how much. I actually have accelerometers and all that stuff to do it manually, but the app actually works well enough for me most of the time.
No app on the Apple store, bummer I'll have to sort out my Android phone that I drowned.
 
Q, The wheel center hole is not washed out way large?

Brand new wheel. The wheel center hole makes no contact, it is larger than the nut at the center of the mounting plate.
Q,Using flat head machine screws so the screws ?
The screws are flat head, but they are ¼-20 shoulder screws that are a very tight fit in the holes on the wheel. The screws are designed for the application.
Q,The machine seem to run smooth with not having a wheel?

Yes, no vibration. There is another wheel on the spindle at the opposite end.

I actually bought two of these wheels from AFT Fasteners. One of the wheels was so out of balance that it is being returned. The problem was the grinding wheel was not glued to the backing plate on center. It had about ⅛" runout. I suspect this one has a similar problem, but to a smaller degree. I mentioned above that I had dressed the wheel face and the inside and outside. The inside is hard to dress, the screw heads get in the way the last ¼" or so.
This would be a Hack method if the wheel is centering pretty tight to spindle center
Set your table flat and C Clamp a couple paralells to your table to hole the wheel on one place with these to the left of your wheel.
Glue or double back tape two hex nuts to your table at 8:00 and 10:00 so the left wheel back sets on those nuts, with your wheel's 3:00 place setting on a gram weight scale to find the heavy area. My gram weight scale is 5/8" tall so i would use nuts tha tall. Use a old carbid drill and diill some balance hole in the wheel OD.

Likely you could set some sand to get a rought idea of how much wheel to drill away.from the OD.

Another Idea if the wheel may be coolant logged is to soak the wheel in a mix of washing soda and water a few days (not baking soda but Washing soda).

*Guess I would try the washing soda bath first

The scale looks useful, I will order one. The scale I used to weigh the bolts is a standard O'Haus dual beam lab scale.
 
Try adding washers under the screw heads. Grind the washers to shave a little weight to fine tune. There is a spreadsheet from @Conrad Hoffman floating around that describes a trial and error method that works well to balance - you may be able to use a smart phone with accelerometers built in as a vibrometer. There's also an app I use that does the same as the spreadsheet, it's called "Adash Balancer." It might ask you to add weight between the holes, you can usually split it and bias between the holes based on their angle to the recommended weight location to get the same effect.
Eric, that sounds interesting. I need to find Conrad's spreadsheet and see how it works.
 
One idea I had when I read Buck's reply above is to remove the cast iron backing plate with the grinding wheel attached, then balance it as an assembly. I have an old wheel balancer designed for surface grinder wheels with standard hubs (the type where the arbor sits on two pairs of round discs). Similar to this Vertex, but a lot older:

balancer.jpg

This wheel does not have a standard hub, but it might be possible to adapt it or make a spindle for it on the lathe.
 
One idea I had when I read Buck's reply above is to remove the cast iron backing plate with the grinding wheel attached, then balance it as an assembly. I have an old wheel balancer designed for surface grinder wheels with standard hubs (the type where the arbor sits on two pairs of round discs). Similar to this Vertex, but a lot older:

View attachment 427026

This wheel does not have a standard hub, but it might be possible to adapt it or make a spindle for it on the lathe.
Iv'e used that type of balancer on 6" wheels and it worked fine. In a bind I have also used parallels packed up on the surface plate not perfect but better than nothing.
 
QT Op: (I actually bought two of these wheels from AFT Fasteners.)

New wheels not fitting the spindle or out of balance should not happen unless they are junk quality wheels. Check your wheel mount hub diameter. it should be tight with a .003 shim on a new wheel.

*Balancing a coolant-soaked wheel will not work because using the wheel with coolant will remove the hardened coolant and then the wheel will become out of balance again. Plate mounted wheels don’t need balancing if they fit the spindle less than .003 sloppy.
The screw bevels usually will centera plate mounted wheel if the big hole is washed out. One must use beveled head screws (flat head machine screws).
.
 
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QT Op: The problem was the grinding wheel was not glued to the backing plate on center. It had about ⅛" runout.
This is so out of order I wonder if you are getting counterfeit wheels.
I have used and mounted so many plate mounted wheels with no problems and no balancing..and never a new wheel with 1/8" run out at OD or face.
Do measure your spindle wheel mount center hub
 
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Try adding washers under the screw heads. Grind the washers to shave a little weight to fine tune. There is a spreadsheet from @Conrad Hoffman floating around that describes a trial and error method that works well to balance - you may be able to use a smart phone with accelerometers built in as a vibrometer. There's also an app I use that does the same as the spreadsheet, it's called "Adash Balancer." It might ask you to add weight between the holes, you can usually split it and bias between the holes based on their angle to the recommended weight location to get the same effect.

No real trial and error involved, though you need a starting test weight. It's call a 4-run balance and gives an exact answer.
 
No real trial and error involved, though you need a starting test weight. It's call a 4-run balance and gives an exact answer.

I only meant that you "try out" the weight in different positions, then measure the vibration change (or change in balancing error) to determine the correct weight and placement. Perhaps not technically correct use of the term, I suppose.
 
This seems to have been covered, but perhaps this adds some catalyst. I take one of my T&C or surface grinder wheel hubs all 1-1/4" fitment, and mount the plate wheel on that and static balance as per usual on the Anderson "wheel type" balancing stand. Weight comes off of the perimeter of the abrasive with an 1/8' -3/16" carbide drill. I have the balance stand centered up on the drill press, for the process. I've been doing this since the early 1980's, successfully
 
Not really covered until the Op solves his problem.
Plate mounted wheels run darn good in-balance just mounting them.
And to drill one is not good because your grinding will run into where you drilled.

I think that wheel for hSS steel is not the best process for grinding Hss..but that is another subject.
 
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A little progress. When the AO wheel is removed, the grinder runs without much vibration. I'm sure a vibration analyzer would still see something, but with the wheel installed, anything I put on the table would bounce around and vibrate. With the wheel off it just sits there.

I followed Cyclotron guy's advice and mounted the AO wheel on a Sopko adapter, so now I could balance it if I had a balancing arbor to match. The wheel was a very close fit to the Sopko adapter so I feel good that the center was preserved. I am going to make a balancing arbor, which I have been saying I would do for a couple years now.

In the mean time, in today's mail I received a CBN wheel from Shars. It appears to be quite nice, but the hole size does not match the original wheels (or the AO wheel). The original wheels take standard ⅜" shoulder screws (which have 5/16" threads). The CBN wheel takes 7/16" shoulder screws. If such a thing is a standard, I could not find it by google search, however, I found some in my screw collection. Unfortunately they are threaded ⅜". They are a very tight fit to the holes in the wheel. I have a bunch of them, so if someone else runs into this problem, contact me. The ⅜ screws are on the left, 7/16 on the right in the photo below.

IMG_3428.jpeg
I'd be interested in knowing if my summary is likely correct. i.e. did plate mounted wheels change at some point from using ⅜" to 7/16" shoulder screws? Was 7/16" once a standard for shoulder screws?

Also, Buck you said AO is not ideal for HSS. Probably CBN is better? What is wrong with using AO to grind HSS? Even though the grinder was vibrating, I used it to sharpen some drill bits yesterday, and I am pretty happy with how they turned out:

IMG_3429.jpeg

This was my first attempt at two facet sharpening. I like it, it's fast and it is the only method available for me for drill bits bigger than ¾", like those in the photo. I burned a couple of bits, but they are HSS so I am not too worried. I found out that I need to dress the wheel more often than I expected, otherwise the grinder would overheat the drill bits.
 
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