Truing a diamond or CBN grinding wheel.

I know ho to true a regular grinding wheel with a star wheel or maybe a mounted diamond. How is it done on a diamond or CBN wheel? Is the matrix soft enough to use a star wheel? Diamond is expensive and you do not want to eat up a lot of wheel messing around to get it right.
Bil lD.

Generally you clock the wheel in to a thou or so of true running then dress with a brake trueing unit or just effectively chunks of old grinding wheel.

This seems to keep coming up to the surface.
First make sure you have a dress or trueable wheel. These have a thickness from 1/16 to 3/8 worth of diamond on them.
Plated wheels can not be trued, they are one layer of diamond thick and have to be indicated in. Do not try to true one by outside methods and do not stick them,.
Dressable wheels have a distinct layer of green, copper, brown or black. Plated wheels are shiny silver colored. It's a chrome plate holding the one layer of diamonds.

So ass-u-ming a resin or metal bond wheel with depth.
Motorized dresser, brake unit, free spinning unit at an angle, even a OD grinder can be used. All sort of a grind away method.
What you really want to do is pull away the bond and let the diamonds fall away not having to deal with them.
Fanatics also want to leave a nice "bond tail" behind the exposed diamonds giving more support to the grain.

It will be trued when shipped, This is has to be done to remove the "skin' left from the pressing cycle.
Usually you can clock in very close to the mount it was on when trued after pressing. Note the this process is not nice on DTI tips and puts flats on them.
It still will not be true to the original dress or act like a trued on mount wheel but this helps a lot.

Moly sticks are sometimes used just like a dressing diamond, it is a slow and painful process. Normally only for touch up work and radius forming.
Popular in use with angle/radius dressers when that is what you have on hand.
It leaves a rather glazed wheel but you can stick it back open. This method attack the diamonds. Akin to watching paint dry or corn grow but does have it's uses.

All this but in fact it is so easy-peasy. Strangely there are shops who will bring me wheels to true up or dress angles into for them.
A past thread here and in it I point to a older thread with some pictures.
.https://www.practicalmachinist.com/vb/abrasive-machining/truing-resin-bond-diamond-wheels-161958/
Bob
PS..... no star wheels, and no single point diamonds.

One of the simplest way to true diamond wheels (after all is done to centre accurately on the hub) is to run it against mild steel plate until it runs true. Use a soft dressing stone after to open the surface. This is what I do with my surface grinder wheels. I am not using CBN wheels but I would think diamond dresser should work as CBN is softer.

How about really fine diamond wheels? I've trued some fairly fine (16 micron) with improvised brake dressers but I use a couple of D7 wheels regularly and they don't seem to like it. Perhaps using just too coarse of a grinding wheel in the dresser.

An aside- I use form cutters (gear cutters) in carbide quite a lot, and little tiny modules like M0.09 or so- they must be made with a formed wheel, but how do they make the form? These have a very fine finish and are really accurate, I have old stock cutters that must be 40 years old too. Cutter diameters from maybe 5mm up to 14mm or so, fewer teeth on the little ones but generally a dozen-ish. Maybe this is better in another thread?

Being a tool and die shop I do a lot of surface grinding of tool steels and carbide, mostly with CBN and diamond wheels. I have tried various ways to derss the wheels and found that a brake dresser is the way to go for truing. Then the wheel must be "sticked" with an aluminum oxide stick to clean away the matrix from around the abrasive. The only thing I hate worse than dressing CBN and diamond wheels is boring soft jaws!

Thanks for the replys. I never thought of indicating a wheel, but it makes sense.

Here's some posts from this and other forums I saved on the subject.

I can say that running some 1018 into the wheel repeatedly will get it true and flat but it takes a lot of patience.



I use old aluminum oxide and silicon carbide wheels broken into convenient pieces clamped to an old 123 block on the chuck. Most of the time I dress by hand and just force the old wheel into the diamond wheel. If I suspect I have dressed an angle over time I mount the wheel segments as described and let the machine true the wheel. I have never heard of using a single point diamond to dress a diamond wheel. I would think that you would get a lot of rubbing and heat. Maybe it works I don't know.
Like

I've seen this tried on several occasions, but I've never seen it work.

With enough patience you can true a diamond wheel using a soft piece of steel like you would a diamond point on a conventional wheel. It's a very, very slow process and you have to stick the wheel when you are done to open it up. Since the diamond won't grind the steel its dulls the diamonds to the point that they generate enough force to fall out of the bond.

We use a piece of soft steel (much like you would use a dressing stick) to intentionally dull diamond wheels when grinding high clearance angles to reduce edge chippage. It's a great trick when you don't have a fine enough grit wheel to give you the finish you want.
Bob

All you need is some kind of low speed gearmotor with a dressing wheel attached to it. Pretty simple.
The whole point of a brake controlled truing device (the long name) is to make sure the dressing wheel does not get up to the speed of the grinding wheel.

The "angled dressers" are pretty worthless and a pain in the you know what to use. You may as well use a chunk of soft steel and a dressing stick.

Maybe find a local carbide shop and have them true it up on the adapter for you. Then you just stick it when it loads up.
Once a diamond wheel is mounted you should not take it off the hub unless you've got money to burn.
Bob

I have posted this before, this is how is is done with out any expensive tools or brake dressers.

First-Get a MILD pices of steel, 1018 or somthing similar. Grind on this and it will TRUE your wheel.

Then you need to get aluminin oxide dressing sticks. With your coolant on you feed these sticks into you wheel and it will open upen the pores of the wheel so you can grind. You want the wheel to suck the stick into it, then you are good to go.

We grind carbide on a daily basis on an okamoto surface grinder and this is the process we have used for years, 30+.

Please remember-truing the wheel gets it to run true.

Dressing opens it up to cut free.

We use a 150 grit aluminum oxide stick available from norton.