Thread cutting, making your own sizes?

  1. earthman Member

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    No, not had time,......maybe this weekend.:)
     
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  2. 123hotchef Member

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    cool u can give me some pointers soon then!
     
  3. Hood

    Hood If it walks like a duck....

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    Threading is easy, once you have done it you will wonder what all the drama is about.
     
  4. 123hotchef Member

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    inner and outer?
     
  5. Hood

    Hood If it walks like a duck....

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    Internal is a bit more tricky if it is a blind hole but if a through hole then no different.
     
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  6. earthman Member

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    While we are on this subject, my lathe came with the thread cutting dial slightly away from the leadscrew so it wasn't turning, is this normal,.... do you only adjust it up when you actually want to cut threads or is it OK to leave it engaged all the time? Maybe it could create excessive wear on the leadscrew I guess??

    16t.jpg
     
  7. 123hotchef Member

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    they just twist of the lead screw normally when not in use
     
  8. Hood

    Hood If it walks like a duck....

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    Yes that is normal and as you guessed it is to stop wear.
     
  9. earthman Member

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    Yes, just a twist and a nip on the allen screw holds it there, thanks chaps.:thumbup:
     
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  10. jordhandson Member

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    I have been over the last couple weeks figuring out how to do some threading on my Colchester Master and today I did a nice M16x2 thread I am well chuffed as for my next on the side project I want to make a tool cutter grinder as they are loads of money to buy
     
  11. earthman Member

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    1,369


    Over 3 years old and not one comment, hope that he's sorted by now.

    Now, I've always wondered, what is the speed of a power feed on a lathe? I have to swap out the cogs for thread cutting on mine, is say the 0.5 pitch, would that be the same/OK to use as a power feed??
     
  12. 123hotchef Member

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    oh man the adjusters i am making are internal and blind one end left the other right!
     
  13. Hood

    Hood If it walks like a duck....

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    You could always get a right hand and a left hand bar and use them upside down and spindle opposite rotation than normal. That way you can start inside and work out.
     
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  14. Hood

    Hood If it walks like a duck....

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    Assuming of course your chuck is not screw on or if it is you have a method of locking it so it won't unscrew in reverse.
     
  15. Hood

    Hood If it walks like a duck....

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    Probably the key sheared in the feed shaft mechanism.
    If your lathe doesn't have a separate power feed then you need to use the leadscrew. I suppose it depends on the size of lathe, type of tooling etc but I tend to use 0.15mm/rev for finish cuts and 0.2-0.3 for roughing.
     
    Last edited: Dec 13, 2019
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  16. jordhandson Member

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    I have seen this guy show some good tips

     
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  17. earthman Member

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    From about 14.30 in he's making passes/cutting the thread, how do you gauge when to wind in the cross slide a bit, to take a deeper cut and engage the lever for the feed/leadscrew?

    If you advance the cutter into the piece and you are a bit slow/late with engaging the feed, won't the start (or end in this case) of the thread be somewhat ruined??:dontknow:
     
  18. Hood

    Hood If it walks like a duck....

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    Don't be fast or slow engaging the halfnuts :D If you are it won't just be the start or end that is ruined it will be all.

    For a lathe with an imperial leadscrew and when doing a metric thread you have to keep the half nuts engaged at all times until the thread is complete. That may make it a bit more difficult to feed back in unless you can vary the speed (VFD etc)
     
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  19. earthman Member

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    1,369
    Best just to leave it engaged and use the on/off button and forward/reverse of the motor instead, I've heard that's another option for a beginner? Not so bad on a through hole job, not so sure how that could work on Joe's example,..he's starting each cut at the base of a blind hole.
     
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  20. Hood

    Hood If it walks like a duck....

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    11,655
    Location:
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    Yes, more awkward stating internally and not being able to disengage the half nuts. If you have a VFD you can slow it down for going back in to the start of the thread but if you don't then not easy, probably best just to cut conventionally and have enough of a back groove to allow for reaction time.

    Personally I would say use the thread dial for imperial threads (if imperial screw) that way you can easily reposition internally.
     
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