lathe tool from estate sale

[ericc]

I bought a couple of bits from an estate sale. It has been mentioned that this is a good way to get started because often the tools are good made in USA types and are already ground. There were 5 tools in the lot, and I think that they cost $3. Here is a picture of two of them.



The short threading tool worked great. Nice cut after a little honing.

The tool on top with the markings gave me a lot of trouble. It is sharpened as a parting tool on the left and a right hand turning tool on the right. It just would not cut cleanly. If it was advanced too far, it would dig and the tip would degrade and stop cutting. After touching it up on the wheel, it started cutting again, and I was able to finish. When I got home, I took a good look at the tip. It was smeared. Odd..... I touched the tool with a file, and it skated. Good and hard. Next a spark test. It sparked as A-2!!!?!?!? Why would a tool manufacturer make a tool out of A-2? It's cheap, but even cheaper carbon steel would be fine. Hmmm....google dumb, huh? I typed the numbers into a web search, and up popped a 5/16" C5 carbide chamfering tool. The carbide nose was broken off, and the user I bought it from ground it down and attempted to continue using it as a lathe tool. It probably worked a little on aluminum. The grind wasn't all that bad, but I could improve it. His lathe went high, so I couldn't afford it.

So, when the tool doesn't cut right, it might not be the grind. Since this was a brazed carbide tool, the A-2 probably wasn't full hard since it was not expected to do cutting duty. I don't think that I will try to heat treat the tool. It will probably be forged into a decorative punch or something like that.
:thinking:

 

[Malave16]

I wouldnt mess with that bit on top. I got a similar one on a box of old bits that came with my lathe. I spent almost 2 hrs grinding a parting tool out of it to find out it was too soft for what i was triying to do with it.

 

[hdskip]

The top tool appears to have been a brazed carbide tool at one time. If so the remaining bit is dead soft.
Gary

 

[Frank Ford]

I have a friend whose father (long gone) was a working machinist. He gave me a sizable handful of his dad's old lathe tools and told me to study them for ideas on how to grind HSS lathe tools. They have been a valuable part of my education, and I suggest we all can benefit from looking at the fossil record of hand-ground tools for some guidance on how other guys did things as we develop our own style and technique.

 

[ericc]

Yeah, it is interesting to see other people's HSS ground tools. It gives you a little jolt when they cut better than yours, too. But, it looks like this was an example that was better not to be followed. It's funny; the file test seemed to show it was hard, but I was using a cheap HF file in a community shop. Many times, it seems, alloy steel can be work hardened pretty badly. Since the cutting end of the tool was rubbing, it was probably work hardened significantly. I picked up a twisted off auto bolt from the street and did a file test on the end. It skated even a nice new fine file. When I ground the work hardened end off, it cut just fine.