What geen grinding wheels for tools

I have been told by a few members that I need a green wheel on the grinder for sharpening my lathe cutting tools. Just looking on ebay & the one I have up says green Silicon carbide. Then which grit to select. I am guessing fine. The choices are. Rough 46. Medium 60. Fine 80 & Finer 100. Any idea's Thanks. Also do I need a diamond wheel for sharpening carbide tipped tools. 

Steve.

Edited By Steviegtr on 23/01/2020 15:30:49

Hello Steve,

Don't use fine grit wheels, they tend to glaze over. Green Silicon Carbide wheels for carbide tooling, white wheels for HSS and steels.

Keep the cutting sharp and open with 46 or 60 grit wheels, finishing the edge on your carbide tooling with a diamond wheel. That can be a fine grit wheel. They are really quite affordable these days

Regards Brian

Thanks very much for the answer. Re-thinking I need to get a small grinder for doing this kind of work because my other is a 6" with coarse-ish wheels in. I need that for when I am Tig welding & fab work. Maybe a little 3 to 4" one.

Steve.

I would get at least a 5 inch wheel size for tool sharpening perhaps 6 inch, and the better make that you can afford the better as usually the cheaper grinders have crap wheel holding washers which allow the wheel to wobble and the tool rests are made of thin cheep material.

David

You will also need some means of truing and sharpening your wheel.

The one I have is a Sealey. Might as well stay with that. Not the best of quality but my garage is no tool room. Thanks for the inputs.

Steve.

I would not bother with a green wheel for carbide, diamond wheels work very well, are much safer, and don't cost a great deal. I have a couple of green wheels but have not used them for years and don't expect I will ever use them again.

Doug

They are OK if you are doing some heavy work like reshaping the working face of a carbide tool, to be finished after that with a diamond wheel. But if most of your work is in maintaining an existing tool shape I would agree with you

Brian

Steve,

Are you referring to a bench grinder or an angle grinder? If the latter, I wouldn't be using that for tool sharpening. I don't see how you would use a bench grinder for TIG and fabrication work. I've never seen a bench grinder with 3" or 4" wheels, either, but then I have lead a sheltered life!

John

No my Bench grinder is a Sealey 150mm. I have various angle grinders from a 100mm through to 180mm & a huge cut off machine 340mm . I mainly use bench grinder if I am trimming a piece of flat bar etc when doing welding. Did not want to tie up the grinder just for sharpening cutters. But from some replies I have had, it may be wise to keep one end for grinding & the other with a Diamond wheel for doing all tools.

Steve.

Steve,

Thanks for clearing that up, Steve. I obviously got the wrong end of the stick.

John

A diamond wheel produces a fine finish, and will sharpen carbide tips. But it really only suitable for honing HSS tools.

A diamond wheel is not suitable for removing lots of stock, only for finish honing.

So my advice is:

Grind HSS with a carborundum wheel, and hone with a diamond.

Grind carbide with a green wheel, and hone with a diamond.

Howard

Edited By Steviegtr on 23/01/2020 23:35:27

Stevie, I'm not going into which wheels to get as that's been covered by those with more professional experience than me.
Re. diamond wheel truers, I have a single point one in a 3/8" bar, but only use it on the Clarkson tool and cutter grinder. This has a proper dovetail slide, so I can mount the bar in a holder and skim the wheel accurately. I've tried using it on my bench grinder(s) similar to yours, but struggle to get a good flat finish due to lack of a sliding toolrest.

One of THESE works well freehand and can cost very little money. It has the advantage of presenting a flat surface to the wheel, rather than a single point. Essentially small diamond grains in a block on a handle; mine came from ebay for about £3.

One can also use a Devil Stone, a bit like a normal carborundum bench stone, but designed for truing grinding wheels, rather than hand sharpening planes and chisels.

Note that the resin bonded diamond honing wheels also need truing up. The diamond grit on these is retained in something like a hard rubber compound, which needs initially truing, then having a new surface exposed from time to time.
This is also done with a stone, similar to a Devil Stone, but counter-intuitively, it's quite soft, in the same way that a green grit wheel for grinding carbide is quite soft.
They are available from many sources, but mine came from Axminster Power Tools. Their description says it just cleans the wheel, but I did find it also trued mine up. Note though, that my Diamond wheels(s) are the resin bonded type on an aluminium disk, rather than those with grit embedded in a metal coating on a steel disk.

Bill

Edited By peak4 on 24/01/2020 01:11:28

Any thoughts on CBN ?

Expand please for the less fortunate of us that cannot read cipher.

CBN - Cubic Boron Nitride - is used to grind hardened steel, see here.

Thor

In the perfect workshop you would use a CBN wheel for HSS and a Diamond wheel for Tungsten Carbide, I would think that as Diamond is harder than CBN perhaps all you would need in the average model engineering workshop is the Diamond wheel. Reason is that Diamond is affected by steel at high temperatures, an expert will be along in a minute with a full explanation, I am sure.

CBN happily grinds HSS and carbide, but they are rather expensive. The nice thing is that a CBN wheel has the grains held in a metal matrix electroplated on a mild steel base. They don't shed grit and are very unlikely to explode at normal grinder speeds! This means that they don't need guarding, which is just as well as they tend to have a much wider face than a standard wheel. Look at the videos on the Eccentric Engineering site - he uses them with the Acute grinding system. I bought one from these people in Didcot and fitted it on one side of an ELU grinder, the other having a allox wheel, for my Acute grinder.

Just had a look. They are expensive. I guess it comes down to how much you use the lathe. I cannot probably justify the cost. Tomorrow a friend is meeting me at autojumble & giving me 3 different types of insert's. To see if I can get a toolholder to match them. Apparently an Engineering place went bust that his mate worked at. He got stacks of the cutting inserts, so I may have a supply of them if I can find a small enough holder. So far I have had a few differing answers. Green, white. Diamond & CBN. For the use the lathe will get I think CBN is too expensive. Thanks for the answers, will ponder.

Steve.