Thread: Sharpening brazed carbide bits

Green SiC or a or diamond wheel is the go.

I use a cheap diamond wheel attached to the outside of my CBN wheel like this.
These cheap diamond wheels are sold as lapidary wheels come in a range of grit sizes.
SWMBO has a heap of them and they cost less than $20 each

Bob,
I have the same grinder as yours. I'd like to set it up the same way (without the VFD). Can you please give me some details of the CBN wheel? Make, part number, grit, dealer, etc please? I can see a label in the pic, but i can't make it out.
Chris

After grinding to put a decent edge on the tool, I touch them up with a diamond file, even after a while turning, a few rubs brings them back to life again.
Diamond files can be got at the big green shed.
Kryn

Originally Posted by jack620

Bob,
I have the same grinder as yours. I'd like to set it up the same way (without the VFD). Can you please give me some details of the CBN wheel? Make, part number, grit, dealer, etc please? I can see a label in the pic, but i can't make it out.
Chris

I got my CBN wheel from Carroll Wood working http://www.cwsonline.com.au/shop/cat...er--cbn-wheels

Mine is 200 mm x 40 mm wide with a 5/8" bush. Mine is an 80g - what I'd like now is 180g
The new ones have grit on the side as well which would be handy although if you mount a diamond wheel on the side the access to the side grit will be restricted.
If you get a 6" diamond wheel you should have ~1" of side access which should be OK.

Ouch, they aren't cheap! If you could only have one wheel Bob, would it be 80 or 180 grit?

With that large section of CBN on the side I could probably do without the diamond wheel.

I would not use tungsten carbide on a CBN wheel... CBN is horrendously expensive.. Diamond is dirt cheap.. I will use HSS on Diamond...

Originally Posted by jack620

Ouch, they aren't cheap! If you could only have one wheel Bob, would it be 80 or 180 grit?

For MW where tool shaping is common I would suggest an 80.
For WW especially if you mainly buy preformed tooling then 180

With that large section of CBN on the side I could probably do without the diamond wheel.

as RC says I would not grind WS on CBN, use a diamond for that.

I have ground HSS on a diamond wheel - the diamond wheel people generally suggest not to but as RC says the diamond wheels are cheap enough.

Originally Posted by .RC.

CBN is horrendously expensive.. Diamond is dirt cheap.. I will use HSS on Diamond...

Haven't you read the interwebs, according to that you cant use diamond against any kind of steel. It sucks the carbon out of the H.S.S and effects the time space continuum. I'll blame you for blowing up the planet.

People as humble as John Stevenson and myself, might have accidentaly, ground a piece of H.S.S. Apart from the explosion, it all went well.

Originally Posted by Machtool

Haven't you read the interwebs, according to that you cant use diamond against any kind of steel. It sucks the carbon out of the H.S.S and effects the time space continuum. I'll blame you for blowing up the planet.

People as humble as John Stevenson and myself, might have accidentaly, ground a piece of H.S.S. Apart from the explosion, it all went well.

My understanding is the folks saying no HSS on diamond are the expensive diamond wheel suppliers who are trying to max the use for commercial users of their expensive wheels. How much HSS really degrades the diamond would be worth knowing.

I realise this thread is about brazed carbide bits, but I rarely sharpen carbide. Almost all of my tools are HSS or carbide inserts. I currently have white wheels on a 1/2HP grinder. It's fine for putting an edge on HSS tool bits, but hopeless for shaping a HSS blank. It also throws white grit everywhere. An 8" CBN wheel on my 3 phase grinder would speed things up dramatically. I could then finish off on the white wheels or a fine diamond wheel like Bob has. Or even the sanding plate on my Multitool.

Sorry for the hijack Mike.

Originally Posted by jack620

I realise this thread is about brazed carbide bits, but I rarely sharpen carbide. Almost all of my tools are HSS or carbide inserts. I currently have white wheels on a 1/2HP grinder. It's fine for putting an edge on HSS tool bits, but hopeless for shaping a HSS blank. It also throws white grit everywhere. An 8" CBN wheel on my 3 phase grinder would speed things up dramatically. I could then finish off on the white wheels or a fine diamond wheel like Bob has. Or even the sanding plate on my Multitool.

Sorry for the hijack Mike.

I doubt that many folks are shaping carbide.
Mostly I just touch up.
As well as general MW carbide tooling the diamond wheel is great for things like some carbide router bits and masonry bits

I had two grinders with white wheels on them. I gave one to the mens shed and the other to my son.
I still have one 10" white wheel that I purchased 7 years ago but that's in the cupboard - it has a max speed limit of 2500 rpm and although I have a variable speed 10" grinder I doubt I will every use it as the CBN wheel does such a good job.

One thing the CBN wheel does struggle on is Crobalt. Anyone know if that is OK on diamond?

Originally Posted by BobL

One thing the CBN wheel does struggle on is Crobalt. Anyone know if that is OK on diamond?

Bob,
Dunno about Crobalt on diamond. I sharpen mine on the white wheel. It's slow, but I only have one ¼" Crobalt bit for the diamond tool holder so it's not too much of a burden. It did take FOREVER to shape the blank bit though.

Originally Posted by jack620

Bob,
Dunno about Crobalt on diamond. I sharpen mine on the white wheel. It's slow, but I only have one ¼" Crobalt bit for the diamond tool holder so it's not too much of a burden. It did take FOREVER to shape the blank bit though.

I have 2 ¼" diamond tool holders and 5 pieces of Crobalt and use them quite a bit
The last time I bought Crobalt I purchase the 3" long pieces and approx cut the cobalt bit on the diagonal/diamond shape with my thin kerf cutting saw (https://www.woodworkforums.com/showth...=196750&page=3)
It is clearly tough stuff because it took at least 5 time longer to cut.
Anyway this saved a lot of time shaping.