How to balance a cup grinding wheel

[Clive BParticipant @cliveb55652]

I bought a cup wheel to mount on a bench grinder for use with a drill grinding jig (a Reliance). However the wheel is unbalanced enough to cause a lot of vibration of the grinder and leaves chatter marks when I try to use it on a drill.  I dressed the face of the grinding wheel with a diamond dressing block but that didn’t make any difference. Is there a simple way to balance this I type of grinding wheel?

[DC31kParticipant @dc31k]

As I understand it, grinding wheels are usually balanced by means of movable weights on the hub/arbor.

You can look at pictures of a Jones and Shipman 540 arbor for inspiration.

For example, see the three movable weights in the perimeter of this one:

https://www.jubileemactools.com/product/1300-1074-series-wheel-mount-flange/

Other such examples here:

http://www.wmsopko.com/sopko_047_49_54_56_57_59_60_65_66_67_68_69_70.htm

[John PurdyParticipant @johnpurdy78347]

Clive

This is how I balance the wheels on my Quorn T&C grinder.  I do the balancing with an electronic accelerometer, but can be done by trial and error, just takes longer ( or make a jig to statically balance it). The one in the picture was particularly bad.

John

 

[noel shelleyParticipant @noelshelley55608]

That’s neat John ! I had the same problem with a Brierley, but that had wheel carriers with balancing weights, even so the wheel was so far out I had to make extra weights. If the wheel is going on a bench grinder then making a carrier is the easy way and then set it up on a set of ways, otherwise it’s trial and error. Where abouts are you ? Good luck. Noel.

[Howard LewisParticipant @howardlewis46836]

Unless you contemplate doing a lot of grinding wheel changes, making a balancing fixture would take a lot of effort, and see almost no use.

You could make up a spindle with for the carrier, and rest it on two knife edges, and balance the wheel and carrier. Again a lot of suck it and see, even once you have found the heavy spot.

The carrier needs to be fairly snug fit in the wheel, to minimise eccentricity

Getting into “chicken and egg” league, it might be worth dressing the wheel first of all.

My bench grinder vibrated quite badly until the wheel was dressed, so that MIGHT reduce the out of balance a little.

In hobby cutter grinders like the Worden, the wheel, being direct driven, runs comparatively slowly, so out of balance forces are fairly small.

HTH

Howard

[Michael GilliganParticipant @michaelgilligan61133]

With a cup-wheel, I would be tempted to do a test balance by sticking lumps of Blu Tack [or similar] on the inside … just to estimate the scale of the problem.

MichaelG.

[FulmenParticipant @fulmen]

This might give somebody a clever idea:

(Steve Mould tests wheel balancing beads)

 

[noel shelleyParticipant @noelshelley55608]

Very interesting ! Thank you. Noel.

[Clive BParticipant @cliveb55652]

Thanks for all the replies. I quite like the idea of using some blu-tack to get a rough idea of where to place the weights. I’ll give it a try.

Clive

[noel shelleyParticipant @noelshelley55608]

Using the spindle of a bench grinder with possibly another wheel on the other end could be difficult to get meaningful results. The bearings of some cheaper grinders are not great so low speed tests may be pointless. and if running up to speed watch out for flying blu tack. If your near me you can use my J&S balancing ways (N Norfolk). Noel.

[Neil LickfoldParticipant @neillickfold44316]

Interestingly at work, I cleaned out the inner of the cup wheel of the built up metal dust etc inside the inner of the wheel. Quite a bit came out and I did notice that it was not evenly distributed. I also noticed that before I vacuumed it out , that the wheel ran very smooth. After cleaning it out, turned it back on and noticed that it now has a slight vibration.

So I guess over time , the introduced metal dust is self balancing the wheel.

Neil

[David George 1Participant @davidgeorge1]

When I install a grinding wheel, having tested it for damage and it rings when tapped with a soft mallet, especially for the first time. I have a mark on the spindle flange and mark the grinding wheel with a marker pen so that if it is removed it can be replaced in the same orientation radially position. I check for play between the bore of the grinding wheel and the spindle and also ensure the card washers are not damaged, the correct diameter and in place. The wheel if very loose I would discard and either send it back or destroy with a hammer the same as if it doesn’t sound right  when ring tested. I tighten the wheel whatever type till tight but not over tight. Replace any guards and tool supports as necessary. Next spin the wheel by hand and look out for concentricity or fouling on guard or tool support. Then switch on the power for a short time checking for major problems like being out of balance or catching or fowling anything. If reasonably ok switch on again and allow it to settle down spinning. I would then dress the face of the wheel which would normally get rid of any vibrations caused by out of true to the spindle bore and run with little vibration. If the wheel is a flat cup wheel I dress the outside diameter of the w heel to run true with the bore and then the face of the wheel as well. If there is any major run out of the inside of the cup I have dressed that as well with a diamond tip tool. If you have to change the wheel always check for damage and ring with a small soft mallet and re align the mark on the wheel with the mark on the spindle flange. I regularly change from a thin 6mm thick wheel to a flat cup wheel to a tapered cup wheel then to a diamond wheel on my tool grinder.

 

 

David

[noel shelley]

On noel shelley Saiand if running up to speed watch out for flying blu tack.

I struggle to understand HOW  a lumpy of Blu Tack could escape from the inside of a rotating cup wheel.

MichaelG.

[noel shelleyParticipant @noelshelley55608]

At there abouts 3000 rpm there is a sideways ( axial ) component on a cup wheel, the blu tack may well creep to the edge of the wheel and escape ? Many on here have not had a lifetime of engineering experience to draw on and in the world of the HSE even the most perverse of occurrences CAN happen ! Some of us are lucky to have access to the right tools for the job, others may have to improvise with unintended consequences ! Better safe than sorry ?

I had a similar problem to the OP with, A, a Clarkson that twice through it’s wheel off and then a Brierley that shook so badly it was impossible to balance. In both cases due to new wheels that were so badly out of balance as to cause trouble. On buying a J&S balancing way was I able to to see how far out they were and do something about it. Only when near to balanced was it possible to true the wheel with success. The Brierley needed 7 weights to get it anywhere near true. The wheels were bought from a well known company in the trade, the wheels were marked with their own brand, NOT one of the big names.  Noel.

[Clive BParticipant @cliveb55652]

Noel, Thanks for the offer to use your balancing ways, however I live in Kent so travel would not be practicable. I guess that any Blu-tack would bounce around bit (before possibly launching itself) if not placed in the right place making the wheel even more unbalanced on start up. If I try it I’ll take full precautions.

Thanks David for your very clear explanation. I should probably start with trying to true up the outside circumference of the wheel, although I am cautious about making it much thinner.

Clive

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