Bench grinder wheel wobble

I’ve got a good quality 8” bench grinder that I can swap grinding wheels for polishing mops and put the grinding wheel back on and it runs true.

My old 6” Aldi special is a different story. I fancy putting a CBN and diamond wheel on it. The supplied washers seem part of the problem, has anyone managed to method to get the wheels to run true.

Andy

I have a similar lower end of the market 8" grinder. I scrapped the pressed washers and turned aluminium discs with good registers. Also I turned the spindle registers to a better standard, I run a normal grey wheel on one end and a diamond cup wheel on the other.

I repaired a similar problem on a cheap grinder by turning new washers to locate the wheel. They were about 12mm thick and a tap on fit to the large diamiter with a step internally to stop it sliding on too far and the outside was a washer diamiter with the loose fit on the grinding wheel so it would locate the grinding wheel. The original washer and nut for the outside is OK as it is just pushing the wheel onto the new location and paper washers.

David

Edited By David George 1 on 20/07/2020 22:31:05

I am in the same boat with a Lidl 6" grinder/linisher. The original wheel is not perfect but at least is usable. I bought a high quality fine grit grinding wheel, and no matter what I try the assembly is so out of balance that I dare not attempt to use it. The wheel itself appears to be OK when checking its static balance. As Andy says the washers may be part of the problem but from the crude measurements I have made I suspect that the shaft may be bent. I have reached the stage now with it that I am going to replace the grinding wheel with a wire brush and upgrade to a better quality bench grinder.

Peter

I’ve just turned up a 3” x 1/2” disc. Fitted on the grinder with a 8mm wide diamond wheel and without frying it only runs out about 10 thou.

Thanks for the replies

The Abrasive Wheels Regulations are worth a look. It seems from para 49 that the use of aluminium flanges may be incorrect in some circumstances. Our old friends Picador used to sell them but I am under the impression that the company is no longer.

Because mild steel flanges can rust I have mostly used stainless.

Ive just completed the upgrade to an old off hand 6" grinder as described here **LINK** I followed the instructions in Harold Halls book, Tool and cutter Sharpening No38 in the workshop practice series

MickyT

I do like the idea Harold Halls,

Thanks Micky T

I was always told to use a washer of blotting paper either side of the wheel and under the washer. Fortunately I have a good supply as I like it on my desk as I use fountain pens when I can but it is still available on eBay, even if nowhere else.

I was always taught to dress the wheel after mounting.

I had a similar problem and fixed it with a flange bushing. I made the smaller diameter the size of the hole in the grinding wheel. The flange takes the place of the washer. I had some 2 inch diameter steel and used that. I dished out the flange by about .010 to .020 inches. I left about 1/2 inch on the outer edge of the flange. That way only the outer portion of the flange pressed against the grinding wheel. I used a reamer in the inner hole so that it was a close fit on the shaft. I reused one of the provided washers on the outside of the grinding wheel. Worked well.

Hi, the flanges either side of the grinding wheel should be of equal diameter and have the same bearing surfaces and the paper blotters should be a slightly larger diameter than the flanges. Wheel wobble should be corrected, but not by dressing.

Regards Nick.

Many wheels are supplied with a 1 1/4” hole and bushes to suit your shaft. I made the inner flange to include the 1 1/4” bush so it is extra long and less inclined to wobble. It is worth checking that the spindle runs true in its bearings and also between centres if the spindle has the centres in the end, if the shaft run true on the centres then if the new flange is a push fit on the spindle then it could be trued when mounted on the spindle. A new wheel will need to be dressed as even when brand new they are not perfect. I personally think a single point diamond and a guide to ensure the wheel is trued accurately is best. My drill grinder has a fixed diamond and the wheel head traverse slide ensures a dead true wheel, unfortunately truing the wheel is a filthy process and if you forget to close the guard to contain the grit it goes everywhere. I must get the dust extraction working.

Mike

As most people say, the culprit are the cheap pressed washers locating the the inner side of the wheel. Turn up some new ones and make sure the shaft hole is a good push fit. That should fix it. Even on the few cheap 6" grinders I have had through my hands , the bearings and shaft run out, have been excellent. Pity they spoil the things with cheap pressed washers.

Andrew,

+1 for Mike Pooles idea of integrating the flange and the bush. It completely solved my wheel wobble problems. I now have a bench grinder that is a pleasure to use.

Peter

I posted this about seven years ago:

**LINK**

Rik

For blotting paper I would suggest trying Jespers in Harrogate , Castlegate in Wetherby or Fred Aldous in Manchester , Leeds and Sheffield .

The issue of grinding wheels running true is far from straight forward. If the wheel is visibly wobbling or there is vibration, there is a problem. Many wheels have oversize holes that are bushed down to the spindle size - these bushes, plastic now, MUST be a good fit in the wheel and there are several sizes where metric and imperial can be confused, giving a poor fit, thus leaving the wheel out of centre and VERY out of balance. If the wheel has lost it's paper discs then blotting paper or gasket paper will work, these Must be fitted on both sides. Others have mentioned ways of improving the mounting flanges. Most small bench grinders have no means of balancing the wheel, so that it is as true as can be is vital. Once mounted it should be trued up using a truing diamond. If the wheel becomes clogged or blunt then dressing with a star wheel dresser will bring it back to life - a blunt wheel will overheat the work and spoil the temper. NEVER grind aluminium, WHY, check out THERMIT welding for the chemistry. Noel.

I copied the wheel mounting arrangement off a Ferret grinder, a 1.25" diameter sleeve over the existing shaft secured by grub screws, this sleeve had a shoulder for new big flanges, Mike Poole's idea is even better.

As bought the grinder would walk round the bench, now it is very civilised. I use beer mats instead of blotting paper, but lots of wheels come supplied with suitable washers