Sharpening carbide tips

[kelvin2164]

I usually use 1/4" tool steel in a holder for turning, or preformed carbide inserts. Neither of which are ideal for me.
I've seen videos of people maching with the carbide tip brazed on to a steel shank. This looks good for me as overhang is minimal and I can form my own cutting shape. However my normal grinding wheel wont touch them for sharpening.
What is the sharpening procedure.

 

[AlbertdeWitte]

Hi Kelvin

You get a light green grinding wheel that does the job, sharpens tungsten/carbide tips nicely.

Any hardware store selling grinding wheels should also have them

Regards

Albert

 

[Swifty]

That's right, you need silicon carbide wheels ( green wheels ), but only use for the carbide part of the tool, use normal wheel for relieving the steel part of the tool.

Paul.

 

[deverett]

That's right, you need silicon carbide wheels ( green wheels ), but only use for the carbide part of the tool, use normal wheel for relieving the steel part of the tool.

Paul.

That's true until the steel shank and brazed carbide tip line up after repeated sharpenings. Now, I just use the green wheel for the whole job.
Maybe not very efficient and maybe wears the green wheel excessively, but hey, it's 6" in diameter and there's a lot to wear down!

Dave
The Emerald Isle

 

[hula-hula_guy]

Don't be alarmed either if once you get a green wheel it seems to be just disappearing in a cloud of dust. This is normal for these types of wheels. Which brings up another point if you plan to sharpen a lot of cutters you might want to pick up a couple of them if they are in your budget. Here at my work we have a dewalt 10" bench grinder and I myself have seen me take at least a 1/4" of wheel off relieving cutter shanks for in the mills, or making lathe cutters. Invest in a piece of carborundum too for dressing your grinding wheel. You can square the grinding wheel face up really easy with these and do a nice light final finish on all your cutting edges. Hope this helps.

 

[petertha]

..you need silicon carbide wheels ( green wheels ), but only use for the carbide part of the tool, use normal wheel for relieving the steel part of the tool.

I've heard this too, Paul. Can you elaborate? Is the problem that the shank is just plain steel & will gum up the SC wheel?

I have a green wheel & used it (inadvertently) to sharpen a HSS parting blade, tough stuff with cobalt or something. Actually it seemed to dress it quite well & left a mirror finish. But is this (HSS grinding) a bad thing for some reason?

 

[DJP]

I sharpen carbide tipped cutters using a green wheel as described and it works. However, I recently picked up some carbide inserts of all shapes at an estate sale. On my mill I made holders for the inserts with either a retaining screw or a clamp. These inserts have multiple usable corners so they last a long time. Since then I have not used the green wheel.

Just another input to the discussion.

 

[Swifty]

The bond in "green wheels" that holds the grit together, is designed to break down rapidly to produce fresh sharp grit. Once the wheel hits the soft shank on a brazed tool, it just disappears as it removes too much grit. Generally, there is not too much carbide to be removed, just a touch up to re sharpen it. I have always used a double ended bench grinder with a green wheel on one end and a grey wheel on the other. When the carbide is flush with the shank, I just hold the toolbit at a different angle to use the grey wheel to relieve the soft shank, then finish the carbide on the green wheel.

Paul.

 

[Wizard69]

The other option is diamond wheels. These are more affordable than in the past. However they have a problem in that they don't last long if they come into contact with steel. Apparently diamond has an affinity for steel. So you are still back to shaping the steel with a conventional wheel.

As for green wheels, actually any grinding wheel, you can get these in various grades. The Chinese grinder that I got comes with some extremely hard green wheels. They do not wear down like has been described in this thread.

If you just want to touch up an edge don't dismiss hand honing with diamonds "stones".

 

[mcostello]

The Chinese green wheels are a lot harder, they also cut miserably slow and last forever. They feel as if they are made of cement and cut accordingly. When using a name brand green wheel on steel it is amazing how fast the wheel disappears.:redface2:

 

[goldstar31]

If you just want to touch up an edge don't dismiss hand honing with diamonds "stones".

At last, a note of how it should be done! If one wants to sharpen- rather than butcher a cutting edge, one can use as suggested a diamond wheel and once there is an edge, one moves to diamond pastes to finish.

Me, I'm not terribly fond of living in a world of silicosis.

Thank you, Wizard 69 for bringing the topic into the 21st Century.

For those in the best part of the 20th Century and have read Chaddock, might I refresh memories and for those who haven't, he said of his Quorn grinder

'A cut of a quarter of a thous is a whopping cut'

How true!

Norman