Is this a no, no

Been looking for a cup grinding wheel with 20mm bore then found I had two nearly new ones for another grinder that's rarely used but the bore is too small.

I think this would be too dangerous but can the small bore be increased in diameter if so how to do it they have no lead or plastic reducing bushes.

This is one of the solid abrasive wheels (not the aluminum plus abrasive kind)?

I wouldn't attempt it personally. Of course, if someone here came up with a way of doing it ....... I still wouldn't attempt it.

These things aren't that expensive: the risk vs benefit (cost saving) ratio is way too high.

Edited By Bandersnatch on 07/10/2016 01:16:24

Spin it in the lathe and bore it out with a diamond wheel dresser? (Cover lathe bed suitably etc first)

I recently popped in to the place I used to work at before retirement, intention was to grind the ends of some cutters on little Deckle cutter grinder. Got the first cutter set up and started the wheel which broke before I had time to dress it. I can only think it was overtightened, the remains had no form of bushing. For the cost I would buy another wheel it was scary when the wheel let go !

Yes, yes, it is a no, no!

If anyone on here wishes to advise a third party to make potentially dangerous alterations to a grinding wheel, then be it on their head should it all turn nasty (even litigation, like!).

Perhaps better to reduce the spindle size on the grinder, but that, too, may be sized for safety. Why not use the rarely used grinder with these cups?

Be safe. Industry insists on abrasive wheels being fitted and tested by a competent, trained operative, I believe.

I concur completely with Not done it yet who offers wise advice; the abrasive wheel regulation are rigorous and demanding, the manufacturers have to satisfy all kinds of requirements in wheel design and opening out the bore on a wheel will increase the risk of a wheel burst.

​This is one area where safety really matters and it just isn't worth the risk involved

Brian

I have my "Abrasive Wheels" ticket and must agree. Definitely a No No.

Yeah, need a cert now if you want to do it at work, and even at college they prefer it if the teacher does the grinding, i was an exception because i had the cert.. Doesn't mean you can't go out and buy a 6000rpm cutting disk power tool, crazy laws.

The damage they can do though is pretty insane on the big stuff though, so you have a look at how many times this has gone to an act of parlement. No worse than some of the ginormous lathes can do as well. I vaguely know a guy who died using a very big wood turning lathe when a workpiece got thrown out. You don't really stand a chance.

I've heard of people using these on pillar drills when theres no room for any grinders. I use a buffing mop on the lathe but got too many uses for it to go without a proper bench grinder. They're the best part of 30 notes and do a good job, so theres no excuse really.

Overspeeding a wrong wheel or perhaps using it with the wrong material is one of the biggest causes of breakages, and breakages mean damage to you if you're not lucky. 

Few rules;

First of all, know what it is you want to grind, match it up with the right wheel AND the right speed, do not exceed the rating of the wheel. You check this against your grinders top speed in RPM. A good quality wheel will always have this information, if not then it's bin material. 

Then you have to check it for any obvious damage to said wheel, there is the "ring test" for any unseen damage, making sure the bore is a good fit on the wheel(or it will rattle around like nobodys business)

, card backing is intact and it is placed on the shaft with flanges both sides. 

Then you're good to go once everything is fastened up. Try to grind on the front face of the wheel if possible, as this minimizes wear to the wheel and it will probably need truing up from time to time. 

PS. I know that he's talking about a cup grinder so it would be different way of fitting it. It should still tell you what speed it can handle up to regardless. I think it's worth saying because this is basically what they teach you when you do this cert. 

Michael W

Edited By Michael Walters on 07/10/2016 09:02:55