Diamond grinding wheels

[Martin Johnson 1Participant @martinjohnson1]

Well, after many years I have lashed up a tool & cutter grinder, own design using bits of worden, stent, quorn all re-arranged to suit me.

Anyway, I purchased a 4" white cup wheel (no markings at all so probably Chinese s**t) from one of the usual suspects which seems very soft. Dressing it produces ridiculous amounts of grit all over the shop. Even taking grinding cut of a couple of thou can produce more clouds.

I am trying to keep the T & C grinder in the machine shop to avoid rust. I could put it in the welding / grinding area but that is very prone to rust. Carrying it to and fro for wheel dressing is possible, but hard work.

I have been thinking about changing to a diamond / cbn wheel (Arc Euro & others do them). Obviously great for carbide tooling, but what about using them on HSS?

Seems to me it would cut out the clouds of grit when dressing problem. Anyone have any experience good or bad?

Many thanks,

Martin

[Martin Johnson 1Participant @martinjohnson1]

Use on a Tool & Cutter Grinder

[Chris Evans 6Participant @chrisevans6]

First try a quality wheel something like WA60KV or WA120 KV for finer work. (the 120 will burn quicker than the 60 if you need to move metal rough with the 60). Best make another arbour for the wheels.

I have a diamond wheel on my bench grinder and find it to grind HSS well if only touching up or adding small chamfer/radius. Never tried CBN so will watch this thread to see how others get on with it.

[Douglas JohnstonParticipant @douglasjohnston98463]

I have been down the same path and found the diamond wheels (supplied by Arc ) work well on HSS for fine cuts. You mention a grinding cut of a couple of thou, that seems rather a lot to me. When using my Quorn I only take cuts of 0.5 thou max.

Doug

[John HaineParticipant @johnhaine32865]

Diamond is reputed to have a bad effect on HSS but I'm not sure how real this is especially for the amateur where the amounts of material being removed are very small – not like grinding the flutes in a cutter blank! I have a diamond cup wheel on my Quorn, the type where the abrasive is embedded in plastic, it seems to work fine. You also get diamond impregnated steel disks occasionally of a useful size.

CBN is excellent, works for both TC and HSS, but expensive. I bought a CBN wheel for my ELU bench grinder to work with my Acute grinding system – available from Axminster and The Toolpost – I bought mine from the latter.

[Ady1Participant @ady1]

I have actually found that angle grinders can be pretty good for dressing HSS and chopping it into small sections for insert work

Haven't really pursued it much, just did it for quick convenience purposes

[David ColwillParticipant @davidcolwill19261]

I find that diamond wheels are great for putting a fine finish on HSS.

If I need to shape a tool I will use a coarse grinding wheel first. There is some talk of diamond wheels being eaten by steels (the fact that steel contains carbon and so does diamond) but this has not been my experience, I have been using mine for a couple of years now and they are still going strong.

To answer the original question I have not yet dressed any of the diamond wheels though I probably should.

I really must rig up some kind of dust extraction.

David.

[Michael Cox 1Participant @michaelcox1]

Posted by John Haine on 28/02/2018 09:53:45:

Diamond is reputed to have a bad effect on HSS but I'm not sure how real this is especially for the amateur

It is not the diamond that has a bad effect on HSS it is the other way round. Diamond is a form of carbon and when hot and in contact with iron (steel) the diamond form of carbon transforms to the graphite form of carbon and it is absorbed into the iron. Thus the steel destroys the diamond. However, I have used diamond abrasives for taking light cuts on steel and there seems to be little damage to the diamond wheel. Heavy cuts quickly destroy the diamond disc.

Mike

[Nick HughesParticipant @nickhughes97026]

Use Diamond for Carbide and CBN for HSS.

Also use good quality wheels (we used Norton Abrasives for our standard grinding wheels).

Nick

[Mark RandParticipant @markrand96270]

Back to the original wheel, I wonder if you are running it fast enough? Running a wheel more slowly makes it act softer, so it's usually best to stay near the rated speed of the wheel.

[Martin Johnson 1Participant @martinjohnson1]

Thanks for all the responses.

Mark – yes it is probably running too slow, but it is direct on a 2800 rpm grinder, so cannot be changed very easily.

Douglas – yes 2 thou is getting on but I was modifying a milling cutter, so had quite a lot to chew off.

As for the rest, you are confirming what I had hoped that diamond for HSS is not theoretically right, but it seems for light hobby use it is OK.

Off to scan ebay and Arc Euro then………………….

Thanks all,

Martin

[Pete RimmerParticipant @peterimmer30576]

You can use diamond wheels to put an edge on HSS all day long so long as you turn the wheel slowly enough and even better if you use a little coolant. Electroplated diamond products have an initially aggressive cut but settle down to their 'normal' cutting rate quite quickly and stay there a long time so long as you don't overheat them.

Once worn beyond their normal usable life they can still be used to put a very fine honed edge on something but the material removal rate will be minimal.

[SteveIParticipant @stevei]

Hi,

Just a quick comment — CBN doesn't need to be expensive. After a tip off from a friend I have been using new old stock from ebay sellers from ex Soviet Union locations, a cost effective source of CBN. I have a number of Ø125mm wheels and the costs were between US$20-30 per wheel with free post. I use them on HSS I also purchased a "1200grit" CBN low speed lapping wheel which makes no mess for keeping tools razor sharp. For Carbide I use Diamond from the typical hobby suppliers, none of which are cost effective for CBN. I whole heartily recommend CBN for HSS, it does a wonderful job with the minimum of mess.

I would like to get advice of which of CBN or diamond is most appropriate for stellite. Even at the prices stated I want them to last as long as practical.

Steve

[Pete RimmerParticipant @peterimmer30576]

I use diamond for stellite, usually I use it for grinding threading tools as it holds an edge so well. You can get it sharp enough that you have to handle it with care. Doesn't seem to bother the diamond, once again if used at slow rpm. Bit hard to find stellite now though.

[John OlsenParticipant @johnolsen79199]

I think I may have already said this on another thread, so sorry if I am being repetitive…but I have a Glendo Diamond tool sharpening machine that my father bought from the states back in the eighties. It came with diamond wheels in three grits, the finest being 1800 grit. They supplied two of those since apparently these are likely to wear out first. I say apparently since all the wheels are still working fine. These are slow turning wheels, used with a supplied detergent, diluted with a lot of water. So I would say there is no problem with the life of diamond wheels, at least used in this way with coolant. So far as I know, the diamond is embedded in a nickel based matrix. I have mostly used them to sharpen HSS lathe tooling, with the odd carbide tool as well.

The fine wheel gives a mirror finish on the faces of lathe cutting tools. I think a wheel of this type, used at a suitable speed, with coolant would be great on a tool and cutter grinder like a Quorn or similar.

Joihn

[StephenSParticipant @stephens]

Posted by SteveI on 28/02/2018 22:44:23:

Just a quick comment — CBN doesn't need to be expensive. After a tip off from a friend I have been using new old stock from ebay sellers from ex Soviet Union locations, a cost effective source of CBN. I have a number of Ø125mm wheels and the costs were between US$20-30 per wheel with free post. I use them on HSS I also purchased a "1200grit" CBN low speed lapping wheel which makes no mess for keeping tools razor sharp.

Steve

Hi Steve,

Please could you give links to where you get these as I could not find them. I may well not be searching very well though. I would be interested in getting some at those prices.

Thanks, StephenS.

[SteveIParticipant @stevei]

Posted by StephenS on 01/03/2018 02:40:34:

Posted by SteveI on 28/02/2018 22:44:23:

Just a quick comment — CBN doesn't need to be expensive. After a tip off from a friend I have been using new old stock from ebay sellers from ex Soviet Union locations, a cost effective source of CBN. I have a number of Ø125mm wheels and the costs were between US$20-30 per wheel with free post. I use them on HSS I also purchased a "1200grit" CBN low speed lapping wheel which makes no mess for keeping tools razor sharp.

Steve

Hi Steve,

Please could you give links to where you get these as I could not find them. I may well not be searching very well though. I would be interested in getting some at those prices.

Thanks, StephenS.

ebay.com and sellers from ukraine.

[StephenSParticipant @stephens]

Posted by SteveI on 02/03/2018 16:37:48:

ebay.com and sellers from ukraine.

Thanks Steve, I had a look and could not find what I wanted but will have another look, must have missed them.

StephenS.

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