Setting up a grinder

[Pete W]

Those of you with good memories will recall recent discussions on hand-cranked grinders. In the latest, I commented on the difficulty of removing a rusted nut in order to swap the old grinding wheel for a new one.

Eventually I resorted to the Dremel-&-cutoff-wheel and I'm now ready to set up the new wheel. It turns out that there's very little information advice available on this subject.

So, with the new wheel on, there's a slight amount of side-to-side wobble as the wheel rotates. I know I can square (or balance) the wheel by using a dressing stone so that the face is square to the axis of rotation. Is this the right approach?

Pete, with many old chisels to be rehabbed.

 

[CHJ]

Pete it would be better if you can get the wheel mounted without the wobble in the first place.

A couple of questions:

Does the shaft of the hand grinder run true? (i.e. not bent)

Does the wheel mount with a flange Front and Back?

If the former there is not much you can do about it without resorting to an off axis mod to the wheel centre bush.

If the latter then you can fit tapered washers each side of the wheel to true it up.

One way of making those is detailed in an old thread of mine.

Basically it is:

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On offering up the new stone it was found to be running out laterally (wobble), ..........

The cause of this ‘Run out’ I determined was due to the Pressed/Punched flanges not locating true on the shaft.

Having determined that there was no position for either wheel that would provide what I would consider a satisfactory lateral run out setting I overcame the problem by installing “wobble” washers behind each wheel, adjusting/rotating each until minimum run out was achieved..

The washers were made from soft Corrugated Cardboard with one face of the card removed (torn edges) over approx. half the circumference, when compressed these form a tapered washer. (ENSURE there are no pronounce ridges when compressed, if necessary dress torn face with glass paper on flat surface)

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I have also made washers out of a beer mat suitably sanded down to a taper.

 

[Digit]

Did the original wheel wobble or show signs that it had been dressed to overcome a wobble?

Roy.

 

[Pete W]

Um... let's see. The shaft isn't bent. Not sure what you mean by a 'flange' - there are two large, dished washers but I think the problem is that there's very little bearing surface to support the inner washer and keep it square to the axis of rotation.

I can get it positioned pretty much square, but when I tighten the securing nut, it seems to shift just enough to introduce the wobble. I hadn't thought about shimming - I shall investigate.

As to the old wheel, I didn't notice any wobble but the grinding surface was well out of square, which was a prime reason for wanting to exchange the stones.

 

[Digit]

In view of the difficulty you had getting the wheel of, rust on the washers, (flanges) or bits of any paper washers that are usually stuck on the wheels, could be be the course of the problem.
Make sure that the face of the flanged washes are clean where they make contact with the wheel and also where the inner one makes contact with the abutment shoulder on the shaft.

Roy.

 

[CHJ]

...Not sure what you mean by a 'flange' - there are two large, dished washers....

my poor description, should have been "flanged or dished washers"

...but I think the problem is that there's very little bearing surface to support the inner washer and keep it square to the axis of rotation.
......

This sounds like the main cause, can you find a small plain washer that is a tighter fit on the shaft that will register better on the shaft shoulder, this would give the large washer a better register. The alternate is to get a better fitting inner washer machined up.

 

[Pete W]

Chas and Roy, thanks for the help and advice.

Roy's tip about grunge on the inside of the washers was spot on. After cleaning those up, things are much better. There's a little bit of wobble still, but I'll work on Chas's ideas about shimming and see if I can't eliminate that as well.