thread cutting from the sholder

[JT.]

after some errors en other
i spend the hole sunday trying diff things to
see what was the easyest way to optain a desent thread finish
with the stuff i got
best result are thise with the carbit inserts tool upside down
450 rpm
piece is a krieger SS barrel at 1 1/16 dia and 18 tpi
feed just with cross slide no compound used on thise test
0.001 " steps with last one 0.0005" and a clean up at 0.000
had no 30 dg in and out cut (i forgot to make them )
was a little to entousiast to file on the front part i dit not now the tops where so quickly gone

 

[Ray C]

I'm glad this worked for you. Using a little dark cutting oil really helps on SS. Anyhow, were you able to check the fit on the receiver?


Ray

 

[JT.]

I'm glad this worked for you. Using a little dark cutting oil really helps on SS. Anyhow, were you able to check the fit on the receiver?


Ray

i checked it wit a barrel cap thx for the tip

 

[basalt]

I would like to cut away from the shoulder with the tool right side up at the back of the bore for both left and right hand threads but between reversing the spindle, reversing the feed, reversing the tool and doing left or right thread, I'm getting pretty screwed up. My machine only goes down to 70 rpm so a shoulder in a hole scares me. I suppose I could hash this out on some scrap but I'd like to learn all I could from more experienced guys first as it may help me avoid breaking a tool.

For threading into a relief what I do is set up a dial indicator on the bed so I know where the relief is. In the attached picture the hand crank is on the left and secured into the spindle bore with a taper similar to the 3 pieces on the right, which is similar to the way a bicycle handlebar is fastened into the fork tube. The square piece 2nd from the left has a groove with an internal thread to receive the cap, 3rd from left. In the foreground is the threading tool which I ground by making sure the shank was at 30 degrees to the grinding wheel, then I used a square against the shank to set the tool perpendicular to the work. Another way to get a small internal threading tool is to take a tap and grind off all the teeth except one. I cut the internal thread with the tool right side up and from right to left, by hand cranking.