High speed steel tool bit

elf · Post by **elf** » Wed Jan 07, 2009 1:22 am

This is an HSS tool bit I'm in the process of shaping to cut threads on a reverse adaptor for an El Nikkor 80mm lens. It started as 5/16th inch square 2 inches long. The tip is now shaped to 60 degree included angle. The short side is .9mm.

Top view:

Left view or from the top right corner of the Top view image:

I was rather surprised by the amount of color in the last image. Both were just lighted with an Ott-Lite and saturation was increased in CS4.

Both were focus stacked with CS4.

rjlittlefield · Post by **rjlittlefield** » Wed Jan 07, 2009 9:30 am

Ah, this is a fun little tool! Designed for cutting male threads close to a shoulder, I presume? I have an unreasonable fondness for such things -- still use the one I ground 40 years ago to make a reverse adapter for a movie camera lens. Come to think of it, I still have the adapter and the lens too. But I digress...

I suspect the color is caused by a very thin film of oxide on the metal. If you're curious, try washing the tool in rust-removing cleanser. The tool bit I tried just now with full-strength Lime-A-Way cleaned up from obvious amber to colorless steel in just a few seconds.

--Rik

mgoodm3 · Post by **mgoodm3** » Wed Jan 07, 2009 10:24 am

coins turn color too, but you shouldn't clean them.

http://coinimaging.com/coins/1886sdrev.jpg

Jbailey · Post by **Jbailey** » Wed Jan 07, 2009 5:11 pm

Elf:

The lighting is perfect for the subject.
The last time I made a lathe tool was in machine shop class in 1958. It was a tool for cutting an Acme thread on a tailpiece screw. What a nightmare for a beginner! I wanted no more of such.

Jim

elf · Post by **elf** » Wed Jan 07, 2009 7:20 pm

It should be able to cut both female and male threads on the adaptor. The female side will be 52mm and the tool axis will be at 30 degrees, so it should fit. I just have to figure out if it will be cutting left or right hand threads when the lathe is running in reverse and the lead screw is moving the carriage to the right.

I thought about making acme gears for my gear head as they have a better form for worm gears, but decided I needed something to do next Christmas holiday

The colors in the top view are definitely from the heat of grinding. The left view colors may just be reflected. I can't see them with the naked eye (or even with my glasses on). I may have to get a torch (that is one that makes flames for everyone on the other side of the pond) and play with the colors.

rjlittlefield · Post by **rjlittlefield** » Thu Jan 08, 2009 12:40 am

elf wrote:It should be able to cut both female and male threads on the adaptor. The female side will be 52mm and the tool axis will be at 30 degrees, so it should fit.

Makes sense. Just be sure to check that you have things ground and aligned so you have enough front clearance that the foot of the tool doesn't drag. I've ruined more than one female thread by forgetting that detail.

--Rik

lauriek · Post by **lauriek** » Thu Jan 08, 2009 10:41 am

mgoodm3 wrote:coins turn color too, but you shouldn't clean them.

http://coinimaging.com/coins/1886sdrev.jpg

That colouration reminds me of the effects of anodizing!