Hand grinding

I have a small KEF bench grinder which runs at 3000rpm and has two general purpose grey 125 x 16 wide x 13mm bore wheels, one coarse and the other a bit finer.

I want to replace the coarser one with a very fine and soft wheel for hand grinding an almost ready-to-use finish on my small hss lathe tools.

Can anyone advise me as to the grade that I should get and where I could buy it? I guess that if the centre hole is oversize I can make up a pair of thick washers to fit the spindle. The grit size would be 100 or 120 but I don't know about the binder and modern materials.

It should be a cup wheel so that I can use the side, I think.

Thanks

Hi Merlin,

Can't help with the choice of grinding wheels any more.

BUT - if you have to make those washers because the centre hole is over size, make sure that at least one of the washers is stepped to fit the inside dia (bore) of the wheel.

Having a grinding wheel suddenly going off centre at speed, and even bursting can be devastating to say the least.

Hope this is not a `Granny/eggs' lesson.

Be safe,

Sam

Hi Merlin
If the centre hole is larger on your new grinding wheel get a bit if bar out of the scrap box, use your calipers to obtain the exact ID of the stone cut flanges for 2 washers suggest just cutting them just about 1/8" deep from centre of wheel once you have cut both off on your bandsaw you can then put both items back in your lathe to face off. I know that this a 1/2 hours work but much safer than 2 washers
I once saw an operator who had put one with an oversize centre into a large grinder. Had to go to A&E.
Even a ME workshop can be a dangerous place if not careful.

Good luck and keep us posted as to results.

Hi There

Choice of grinding wheel A60K5V. 100 or 120 grit will probably be too fine.

Axminster power tools do a recessed wheel in 80 grit in their catalogue but I found they had 60 grit in stock when I visited them.

regards David

Thanks for the advice. Yes, I would have made substantial fitted discs as you describe.

I have had no success in searching on the internet for a suitable wheel of the required size and grade.

Another problem is that I don't know the overall width of these cup and disc wheels but I guess that on one side they are well off-set from their bore, so take up more space inside the end guard than do the plain wheels. The end guards of my tiddly 15-year-old cheapo KEF grinder are fairly close to the wheels.

I could soldier on with what I have been using quite successfully for the past 15 years, or perhaps I could buy a slightly larger grinder, together with a soft wheel to fit.

Have I got more money than sense, I ask myself.

The reason for turning to this now is that when I first began model engineering about 25 years ago I soon became a disciple of George Thomas, who wrote so well and clearly in 'Model Engineer' at the time.

I made most of his attachments but, because I was then buying basic tools, I could'nt afford the soft wheel that he described in his articles.

Thanks.

Hi Merlin,
Try Abtec Stores on ebay. I bought some cup grinding wheels from them a few years ago and they seem to be OK

Les.

Hi Merlin, Abtec Stores also do a selection of ready made reducing bushes, see the link below.

**LINK**

In industry when buying wheels for small bench grinders, a good selection of these bushes often came with the wheel, all moulded together a bit like the plastic Airfix kits are.

Regards Nick.

If you just want the wheel for finishing, why not consider C.B.N.?

These "diamond wheels" are easily found on E-bay, not too expensive, and the vendor was quite

helpful when I asked for basic information. they are brilliant for finish.

Just worth a thought. Roy.

I am years out of date and have never used diamond tools. I am familiar with common straight abrasive wheels and their maintenance etc but I had better learn a bit more before spending a weeks wages (£10 without overtime) on diamond -bearing stuff. I can't find any explanations on the internet and nothing in my oldish books, so perhaps this is the place to ask for information.

Are 125mm diam. diamond wheels happy at 3000rpm?

Do They need regular clearing/cleaning when used with HSS lathe tools? Every few minutes?

Is the nomenclature the same ie does an 80-grade diamond wheel give the same result as an 80-grit abrasive wheel?

I think that a fine 100 grit wheel would tend to glaze and burn: does the same apply to diamong ones?

Thanks