Is there any good reason to continually run the lathe while threading? My backgear on SB9 is stripped so I run direct at approx 250rpm, switch power off or disengage 1/2 nut at the end of a pass then crank the carriage over until the thread dial lines up, engage the 1/2 nut and power on for the next pass. Seems to work ok with 18tpi on 3/4" CRS. For fine adjustment at the end of the pass I just hand crank.
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Start/Stop Threading
- Thread starter martik777
- Start date
I do threading at 70 rpm. I don't like to think about any higher speeds than that, especially when threading to a shoulder. I guess I could thread in reverse but for the most part, I go slowly.
I use a 60 degree carbide insert (can't recall the number) but it works well. I've also ground 60 degree points on HSS with a gauge and that works just as well. I use my thread dial on the 13 X 40 Enco and I generally get very good results.
Like I say, I'm not doing this for a living and I've got all day.
I use a 60 degree carbide insert (can't recall the number) but it works well. I've also ground 60 degree points on HSS with a gauge and that works just as well. I use my thread dial on the 13 X 40 Enco and I generally get very good results.
Like I say, I'm not doing this for a living and I've got all day.
Well, after a little practice, catching the 1/2 nut at 270rpm is a piece of cake. If you crank out a ways past the end before each pass, you will have more time to react if you miss the thread dial mark. Didn't want to spend more $ on that backgear anyways 
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