# Help: Cobalt cutting tips



## sffone (Jun 19, 2011)

In his book "Ellsworth on Woodturning," David Ellsworth shows how to make hollowing tools using drill-rod steel bars and 10% cobalt high-speed cutting tips. I would like to try making a couple of these tools, but have been unable to find a source for the cobalt cutting tips. Does anyone know where I can order them? Any help will be greatly appreciated.


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## john lucas (Sep 18, 2007)

Just use the High Speed Steel metal cutting bits that you can get from any place that sells tools for metal working. I use 3/16" cutters that I get from places like Enco, Grizzly, and other metal suppliers. 3/16" square cutters will fit almost exactly in a 1/4" round hole. I just glue them it with epoxy or CA. If you ever need to remove them just heat the metal and pull them out. I do have some that are held in by setscrews.
sharpening them is easy, see the end of this video.


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## Hhaines (Nov 26, 2008)

I make the inserts out of old allen wrenchs.....they are very hard, hold an edge very well, and can be made in various sizes, and shapes..... I cement them in 1/2" rod with JB Weld......the ginding needs to be carefully done to keep the tips from getting too hot to weaken the epoxy.....when warn out just heat the tip to remove and replace with tip and regrind......I think that it's not wise for the tip to extend beyond 3/4"....a catch could break the tip off and possibly cause a hazzard....


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## hughie (Mar 22, 2008)

> but have been unable to find a source for the cobalt cutting tips. Does anyone know where I can order them? Any help will be greatly appreciated


 
The tips are HSS steel with some measure of cobalt. Often they simply marked 'cobalt' on the HSS piece. Its variation some manufacturers used to place on them, not so common these days.
As John has said just look for HSS pieces, most engineering supplies and some wood turning supplies will have them, generally you will be looking at M2 grade. In this case buy American if you can. The Chinese quality varies some and allot of it wont hold an edge like your home grown variety.


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