A month ago a 2" + dia. bar of D2 turned up, I faced it to 110 1/4" long and drilled and tapped the ends 5/8-11, the threaded end is for hanging it in a vacuum furnace for hardening I am told.
It was then straightened and centerless ground to 1.999 +-.0005, the grinder nailed it. It is now 62C Rockwell scale hardness as well.
My job is to turn one end to 1.437" +-.001" diameter X 7" long and the other end to 1.500 +- .001" diameter X 5" long. The company that hardened it earned their money as it is every bit of 60 Rc
Due to length I had to turn it in a steady rest over a cats head and a live tail stock center, one of the advantages of having a tapped hole in each end is that one may screw a common hex head bolt in it and create a new center.
I chose a 135 Deg. insert shape to clear the center using a Sumitomo hard turning insert that I believe is cermet, unless parting to center I set the tool height with a ruler, this will probably cause many hobbyists a good deal of chagrin, this lathe is 11 7/16 from the ways to the center of the spindle.
Made a spindle guide to keep the part from flailing around at the back of the machine from nylon, this does the job of what many call a "spider".
It looks like this in use
Hard turning leaves a beautiful finish even when roughing, tomorrow morning the finishing cut will be completed and I will have to nearly double the spindle speed for this as the diameter is now smaller.
Roughed at 200 SFM, .020" DOC and .008 IPR, this is conservative, will spin it at 300 FPM, .005" DOC and a .004" IPR feed which should work nicely, this would be about 700 RPM
It was then straightened and centerless ground to 1.999 +-.0005, the grinder nailed it. It is now 62C Rockwell scale hardness as well.
My job is to turn one end to 1.437" +-.001" diameter X 7" long and the other end to 1.500 +- .001" diameter X 5" long. The company that hardened it earned their money as it is every bit of 60 Rc
Due to length I had to turn it in a steady rest over a cats head and a live tail stock center, one of the advantages of having a tapped hole in each end is that one may screw a common hex head bolt in it and create a new center.
I chose a 135 Deg. insert shape to clear the center using a Sumitomo hard turning insert that I believe is cermet, unless parting to center I set the tool height with a ruler, this will probably cause many hobbyists a good deal of chagrin, this lathe is 11 7/16 from the ways to the center of the spindle.
Made a spindle guide to keep the part from flailing around at the back of the machine from nylon, this does the job of what many call a "spider".
It looks like this in use
Hard turning leaves a beautiful finish even when roughing, tomorrow morning the finishing cut will be completed and I will have to nearly double the spindle speed for this as the diameter is now smaller.
Roughed at 200 SFM, .020" DOC and .008 IPR, this is conservative, will spin it at 300 FPM, .005" DOC and a .004" IPR feed which should work nicely, this would be about 700 RPM