As far as I’m concerned green grit wheels need effective dust extraction to make them worthwhile so my preference is for diamond. dont fall into the trap of cheap chinese wheels they are much too fine for most work unless you sharpen No80 drills daily!!!

I recently started to modify a engraving tool grinder to sharpen my carbide tools on and whilst I have used a diamond cup wheel with a flat plate support to rest the tool on similar to a standard grinding wheel the wheel had a slight wobble on the face which when sharpening carbide turning and boring tools on I would like to dress the wheel true and flat. I have had to buy a diamond dressing attachment which was second hand for just over £100.0 which was a great price from a new one of at least £300.0 .   You also have to have a dressing stick to clear the diamonds in the wheel after dressing and my wheel now runs true and cuts well better than when I first bought it.

Picture of dressing diamond wheel.

Thoughts on using a diamond wheel need attention perhaps a CBN wheel may be easier to dress?

David

CBN wheels often have the grit bonded to the true surface of a steel wheel by an electrolytic process.  Provided they are properly made they should inherently run true, if you tried to “dress” then you would just remove all the abrasive!

In a home workshop and even with the best bench grinder in the world, diamond wheel grinding should be thought of as a light finishing or lapping tool. What the precision grinding industry can and does ought to be ignored since there using optimized, heavy, rigid machines, specialized wheels, the correct flood coolant etc for there high production rates. And for anything other than solid, braised, or replaceable tipped carbide tools, your wheel speeds will be far too high for even finish grinding. Yes it can work for awhile, but the high heat that’s generated between the diamond grit in the wheel surface and non carbide surfaces on the tool your grinding causes a chemical reaction between the carbon in the diamonds and the iron in the steel that seriously degrades and ruins the diamonds.

For all of these reasons, low rpm lapping tools along with at least a bit of water cooling and lubrication are the much better method. The now out of production Glendo Accu-Finish machines ran at around 300 rpm to keep that heat under control. But they were intended as and are only a light finishing or surface lapping machine. I’d be using one of those green grit silicone carbide grinding wheels for the bulk metal removal and shaping, and a slow speed diamond wheel for the finish lapping. Before those Accu-Finish machines were discontinued, they and any other slow speed carbide grinder I know of were quite expensive. $1500 + and $200-$300 for each different diamond wheel grit. There’s one much cheaper and possible way around that. While there easier to find in North America than the UK, I did find this. https://www.einhell.co.uk/p/4418008-tc-wg-200/ With the right diameter of diamond face wheel to pick up the water, and your own shop made tool rest, it might work just as well. Machining your own wheel adapters to fit whatever wheel mounting size and design one of those wet grinders use is probably going to be needed as well.

Having the plated type of diamond or CBN wheels has one advantage, they will not shatter. At the museum, we have two grinders using these diamond wheels which do get used for hss and the occasional drill bit, as well as carbide and the small ammount of steel ground on them will not destroy them quickly like being in an industrial enviroment.

CBN is cubic boron nitride, almost as hard as diamond, used for hard steels because it is immune to being dissolved chemically into the iron which has an affinity for carbon as elevated temperatures, diamond is an allatrope of carbon.

I was looking to buy a 4” CBN wheel a while ago but all the affordable versions come from China and frequently listed as “Diamond CBN”. Not knowing exactly what I would be buying I abandoned my search. I am currently using a 4” electroplated Diamond wheel for some small jobs and it seems to work quite well.

A good source for CBN wheels in 6” and 8” diameters is to look at wood turning suppliers. They are quite popular with some wood turners.

https://www.axminstertools.com/axminster-evolution-series-cbn-wheels-180g-103915?utm_source=tag&utm_medium=affiliates&utm_content=4366&tagrid=71390405&glCountry=GB