Yard Sale Tool Find

[Mark Goulais]

I was gifted a box of old lathe tools; the only ones I can identify are a set of Great Neck high-carbon tool steel. I have a slow-speed grinder with CBN wheels to sharpen my M2 HSS tools - can I use this to sharpen the old non-HSS tools? I've read that "it's not advised" to "I do it all the time". The grinder I bought came with the white stone wheels (which I upgraded to the CBN's), do I put the stone wheels back on to sharpen the old tools or just use the CBN?

 

[Mark Jundanian]

Yes the common wisdom is that high carbon steel will clog up CBN. I have also heard that you can get away with it once in a while.
But consider whether you really want to sharpen/use the high carbon lathe tools, since they don't hold their edge very long?

 

[Dean Center]

I was gifted a box of old lathe tools; the only ones I can identify are a set of Great Neck high-carbon tool steel. I have a slow-speed grinder with CBN wheels to sharpen my M2 HSS tools - can I use this to sharpen the old non-HSS tools? I've read that "it's not advised" to "I do it all the time". The grinder I bought came with the white stone wheels (which I upgraded to the CBN's), do I put the stone wheels back on to sharpen the old tools or just use the CBN?

Good for you for recognizing you're going to get a range of answers, since one size never fits all in woodturning. On the other hand, you apparently haven't caught the "now I'll need another tool" virus. (Don't stand too close to Robo Hippy). The best answer, therefore, is "No, you cannot sharpen those on your CBN wheels, so you will need to go out and buy a second grinder and put your white wheels on it."

 

[Mark Goulais]

Yes the common wisdom is that high carbon steel will clog up CBN. I have also heard that you can get away with it once in a while.
But consider whether you really want to sharpen/use the high carbon lathe tools, since they don't hold their edge very long?

I figured I'd use the "old" tools to practice changing the grinds on tools. If I hear about a certain style of a tool that interests me, I can practice with it before I alter my HSS tools. Speaking of "old", how long have the carbon steel tools been around? All the turning that was done in the European cathedrals was accomplished using them. Also, the 'idea' of using tools countless other makers have manipulated is fascinating to me. Call me nostalgic.

 

[John K Jordan]

Range of answers: OK, here's my 2 cents: Yes, you can sharpen high carbon steel tools on a CBN wheel IF the tools are hardened. The important thing to remember is not to let them get hot enough for the edge to turn blue. If so, you can loose the hardening, the steel becomes softer, and can clog the CBN wheel. Otherwise, it will work fine. Has for me.

If the tools came hardened and are not now and also show no signs of blue, perhaps someone already overheated them then lightly ground away the evidence.

I don't sharpen a lot of hardened high carbon steel tools on CBN, usually only when I grind a custom tool shape. It is VERY easy to overheat a thin cutting edge. Dousing the wheel before the cut with cutting fluid can help. A very light touch can help. Repeatedly dipping the end of the tool immediately in water after every short grind can help. I've done this with non HSS tools with no problems so far. Just be aware; don't forget.

Note that aggressively grinding with a standard grinding will can also overheat and destroy the hardness of the tool.

If the steel is low carbon or unhardened high carbon steel, I would sharpen it on standard wheels.

You can test the hardness of any tool with the file test (use a triangular file and see if it skates on the steel or if it cuts. If it cuts, the steel is soft. You can also buy a set of calibrated hardness testing files. I have this set:

TTC 6 Piece Hardness Tester File Set: Hardness Testing Apparatus: Amazon.com: Industrial & Scientific

TTC 6 Piece Hardness Tester File Set: Hardness Testing Apparatus: Amazon.com: Industrial & Scientific

www.amazon.com

Note also that old tools are sometimes only hardened for a short distance from the cutting tip. I test all old tools with the file test.

JKJ