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Re-boring Grind Wheels

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James Alford13/05/2022 07:23:41
464 forum posts
79 photos

I may be on a hiding to nothing, but it is worth asking the question: has anyone successfully re-bored the hole in the middle of a grind wheel and, if so, how? The only tool that I have that is large enough to hold it is a bench drill.

Both of the 8" grind wheels which came with my bench grinder are so badly bored that they both run out of true side to side so that they make the machine unpleasant and, probably, unsafe to use. With just a wire wheel on it, it is smooth and silent in use.

The holes appear to be bored at a slight angle, making the wheel sit twisted. They are also a little larger than the spindle, but not large enough to sleeve, meaning that they wobble even more.

I have had the tool for too long to return it to Wickes for an exchange.

Regards,

James.

Edited By James Alford on 13/05/2022 07:24:12

Edited By James Alford on 13/05/2022 07:25:07

John Haine13/05/2022 07:35:19
4673 forum posts
273 photos

I suspect that the risks of damaging the wheel integrity and weakening it are too high to even attempt it, to be frank. I don't think they are that expensive, I'd suggest just buying some good quality replacements with bushes if necessary.

DiogenesII13/05/2022 07:40:13
561 forum posts
221 photos

The flanged washers should be the items that control the alignment of the wheel and hold it in truth usually after a bit of trial and error when mounting..

..making new flanged washers has been a long-proven solution to many cheap bench-grinder / wheel ills, the standard ones are usually stampings of doubtful accuracy..

There are probably earlier threads IIRC...

James Alford13/05/2022 07:49:46
464 forum posts
79 photos

Thank you, both.

John: that is what I had suspected, to be honest. Replacement wheels seem to start from about £11.00, but the reviews of most that I have looked at all seem to complain of them being out of true.

Diogenes: That is a good point as well. The washers are stamped, whereas my old, long-dead Black and Decker from the dark ages had substantial machined flanges.

Regards,

James.

David George 113/05/2022 07:51:03
avatar
1839 forum posts
503 photos

Hi James PLEASE don't mess with grinding wheels structure. I have seen the results of incorrectly fitted grinding wheels and it isn't worth the risk. A cheap grinder which had only pressed steel washers was so loose on the spindle which was incorrect size for wheel moved and exploded. The spindle bent, pulled in the tool rest, and exploded the wheel. Part of the wheel was embeded in the ceiling. If the wheel is suspect break it to prevent its use and buy a correct size and type of wheel. There is a qualification for mounting grinding wheels in a work situation it prevents this type of accident wating to happen have a look on the web on how to mount a grinding wheel.

DAVID

Chris Evans 613/05/2022 08:01:24
avatar
2057 forum posts

Somewhere I have my wheel mounting qualification from a course "Abrasive wheels regulations 1971" (date ?) some of the horrific results shown on the course from incorrectly mounted wheels scared me.

I have a cheap bench grinder that required me to turn new flange washers to get it running true and safe, the pressed washers are dangerous.

Andrew Johnston13/05/2022 08:12:00
avatar
6601 forum posts
701 photos

If the wheels are that bad from new then bin them. It would make me wonder what else was wrong with the wheel. It's a grinding wheel; so if you try drilling the bore it will equally grind the drill rendering it useless.

For an 8" wheel £11 is very cheap. Personally I wouldn't touch them with a bargepole. I buy my grinding wheels from professional suppliers and reputable makes. At recommended speeds the periphery of a grinding wheel is doing about 60mph. Being hit in the face with a rock doing 60mph just to save a few quid doesn't seem like a good deal to me.

Andrew

James Alford13/05/2022 08:15:18
464 forum posts
79 photos

Thank you for all of the replies, which have confirmed my suspicions.

I have just had a good look at the machine again and mounted the wheel without the pressings and nipping it up lightly. Turning it by hand, it ran nigh-on true. I also realised that the mounting flanges butt up against a wobbly circlip, not a turned collar, again not helping.

Methinks that I shall be making some modifications to the flanges.

Thank you for the advice.

James.

Clive Foster13/05/2022 08:17:02
3135 forum posts
109 photos

It is likely that the surfaces on which the flange washers sit are also out of true so making new washers probably won't help.

Generally, even on poor wheels, those surfaces are fairly well aligned to the bore. Presumably the basic bore is pressed in when the wheel is made.

Cut your losses and go to a proper supplier. Maybe £30 or so a wheel so not unaffordable. It will cut better than a cheapy and last far longer too if you keep it dressed.

Clive

Chris Evans 613/05/2022 08:37:42
avatar
2057 forum posts

Just think how many years a grinding wheel lasts, I doubt if it equates to a £ a year.

not done it yet13/05/2022 08:39:54
6809 forum posts
20 photos

Care to put up a clear pic of the grinder? No need to actually name it, in print, if a good pic (or from where it originated) is shown. It might save others from the woes you have experienced.

I suspect it may well be yet another case of buy cheap, buy twice…

IMO, grinding wheels are not something to be messed with. They can be dangerous enough, even if in good condition - let alone starting with an inferior product…

John P13/05/2022 09:17:18
406 forum posts
257 photos

In this video Dan Gelbart shows at about 5 minutes 45 some reworking
of grinding wheels.


https://www.youtube.com/watch?v=sFrVdoOhu1Q

For those of us who don't have such facilities China is your friend
via aliexpress who sell diamond core drills which can easily
modify or make up stones from old or even new grinding wheels
such as these.
John

grinding wheel.jpg

noel shelley13/05/2022 09:47:11
1344 forum posts
21 photos

wheel balance is important ! I have had not so cheap wheels from a specialist that were almost impossible to balance and shook the whole machine. It worried me to the extent that I bought a J&s wheel balancer. Andrew is right about speed, If your luck runs out you could find yourself in the dead centre of town ! Noel.

Samsaranda13/05/2022 09:48:31
avatar
1430 forum posts
5 photos

Because of the serious consequences that can happen with a grinding wheel accident I wouldn’t tamper with a wheel, just buy new and as recommended go for quality product, your life is too precious to take risks with, grinding wheels when they explode can kill. Dave W

Mark Rand13/05/2022 09:51:15
1272 forum posts
28 photos

I have re-sized the bores of two grinding wheels. I bought new wheels for a Wolf pedestal grinder (one of the newer ones, unfortunately, not one of the nice cast iron ones). I had assumed that the hubs were 1 1/4", but it turned out that they were 32mm. I opened the bores with a 32mm Rotabroach cutter that I had. I held the cutter in the vice with a V block and rotated the wheels onto it by hand.

To do a better job, I would mount a dressing diamond sideways in a boring bar and use it on the mill.

I recently fitted an Indian seeded-gel wheel to the surface grinder to use for drill sharpening. The wobble was truly appalling. That got dressed on both sides and the rim, then the hub was rebalanced. I was a bit annoyed about the poor manufacture, since it is as easy to get it right as it is to screw it up, but at least the wheel now gives very good results sharpening HSS drills.

If you open out the bore of a wheel to correct wobble, you would need to make a bush or new hub to centre the wheel afterwards. If the hole fits the hub now, it's better to dress the wobble out, though you might want to contrive a tool rest that can be clamped to the opened side of the wheel guard to guide the dresser.

John P13/05/2022 13:27:03
406 forum posts
257 photos

Buying a reputable make or from professional suppliers is no guarantee of getting a good
wheel these days.
The wheel seen here on the left is a Norton wheel from RS not cheap ,the mounting area
was like a rollercoaster track ,the balance was poor but easily corrected when mounted
on this heavy hub ,the centre of gravity is moved to the back of the wheel where there are
two balance rings to even things up .
The other three wheels here all from China all cheap and very well made without the
problems the Norton wheel has , the 2 Quorn wheels are perfectly balanced as is.

John

cup wheels.jpg

noel shelley13/05/2022 13:53:00
1344 forum posts
21 photos

I go along with Johns statements. Properly balanced wheels will work much better, BUT NEVER exceed the wheel speed !!! A slow wheel may well not cut efficiently, at the right speed it will do it's best, too fast it could KILL you. Noel.

jimmy b13/05/2022 15:23:50
avatar
786 forum posts
42 photos

As others have said, I'd not bother messing with the grind stones.

The biggest improvement will be to make some new dished washers. If needed re-cut face they locate off.

jim

Neil Wyatt13/05/2022 15:26:29
avatar
Moderator
19033 forum posts
734 photos
80 articles

And never mount without a card washer between flange and wheel.

Neil

James Alford13/05/2022 17:28:51
464 forum posts
79 photos

Thank you for all of the replies and suggestions. On balance, I shall not attempt to rebore the centres of the stones. Aside from the comments which have confirmed my fears regarding safety, I would have to buy more equipment to do the boring which would outweigh any savings from buying new wheels. I shall make some new supporting washers and address the wobbly circlip on which everything locates. If that still doesn't work, I shall look for new stones .

 

My grandad, who was a very good engineer, dinned nto me the need for cardboard washers either side of the stone. It is a lesson that for some reason really stuck. However, the reminder was was appreciated.

 

 

 

Edited By James Alford on 13/05/2022 17:32:02

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