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  1. #1
    Join Date
    Dec 2019
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    Default Repeat Distance method

    Hello all, Does anyone know how to cut awkward pitch threads with the Repeat Distance method. Or any other method of tracking the thread when chasing dial won't do it or you cant reverse.

  2. #2
    Join Date
    Jul 2016
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    Melbourne
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    Default

    My method of solving this problem on a lathe that couldn't reverse was to make a handle for the far end of the headstock bore and just reverse it by hand. (Note you need to make the handle spring loaded or take it out between passes)

  3. #3
    Join Date
    Oct 2011
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    Norwood-ish, Adelaide
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    Default

    What pitch are you trying to cut?

    Michael

  4. #4
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    Dec 2019
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    Perth
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    Default

    Quote Originally Posted by caskwarrior View Post
    My method of solvingcan this problem on a lathe that couldn't reverse was to mcheersake a handle for the far end of the headstock bore and just reverse it by hand. (Note you need to make the handle spring loaded or take it out between passes)
    Not a bad idea, even on the countershaft if in back gear mode. I was sure there was a method where you measure a distance on the bed though I Can't remember how to do it.
    cheers

  5. #5
    Join Date
    Dec 2019
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    Perth
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    Default repeat distance method

    Quote Originally Posted by Michael G View Post
    What pitch are you trying to cut?

    Michael
    Hi, michael, it's actully 1.41 mm pitch . with drive gear 28 and leadscrew gear 60 on a 3mm lead screw. this is almost exactly 18 TPI which is what I need. I think there were two ways of cutting a thread without chasing dial or reversing the lathe though. will look into it further.
    cheers.

  6. #6
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Thumbs up Lathe winding handle !

    Hi Brookerbj,

    A lathe handle is quite an easy turning job ! These are pictures of mine. I made this quite some time ago and did a write up on this forum.

    21022015-00.JPG 21022015-01.JPG
    I had an old plastic washing machine drum pulley just kicking about and getting in the way so I pressed it into service for winding back the lathe spindle. It has come in very useful.

    21022015-04.jpg
    I made a fitting to go into the original rectangular hole in the middle of the pulley and welded a length of tube to it. The tube is a good sliding fit in the spindle bore and extends to about halfway down the headstock.

    21022015-03.JPG 21022015-05.JPG
    I cut four slits in the end of the tube and drilled holes through to stop the tube from permanently deforming when the cone shaped wedge forced the four tube sections against the inside of the spindle bore. I made no attempt to machine a taper in the end of the tube, I just ran a countersink bit on the end before slitting.

    There is a rod running down the inside that is threaded at both ends. The cone is Loctited on one end and a nut and washer used at the other to pull the rod and expand the end of the tube in the spindle.

    The brass ring is just a stop so that the pulley does not hit the gear cover. I added a handle to make turning the pulley wheel more convenient.
    Best Regards:
    Baron J.

  7. #7
    Join Date
    Aug 2008
    Location
    Melbourne
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    34
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    1,075

    Default

    Found this in a old machine operation book, starts at the bottom of page 454 under the heading "Cutting a thread without the reverse belt" and refers to the "definite distance" method

    IMG_20191210_180634.jpgIMG_20191210_180649.jpg

    It does, however, seem to imply that the thread being cut must be in the same units as the leadscrew, so it might not help you. You could possibly calculate how far out you'd be, as it would be the same amount each pass, and compensate by moving the compound, but now it's starting to get way too complicated...

  8. #8
    Join Date
    Oct 2008
    Location
    Cairns, Q
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    Default

    Quote Originally Posted by BaronJ View Post
    Hi Brookerbj,
    A lathe handle is quite an easy turning job ! These are pictures of mine. I made this quite some time ago and did a write up on this forum.
    Some time ago I made a similar arrangement for the old Brackenbury and Austin lathe, but instead of the wheel and handle made a two pin coupling. One half is held in in the headstock spindle as you have shown. The other half is held in a portable drill's chuck - crude, but for occasional use it saves a lot of winding with a handle. Obviously there is a limit to the lathe size for this arrangement, but it works well on the 9x18 B&A lathe. I take the back gear out of engagement while rewinding. This means that the drill does not have to handle the extra resistance of the back gears, countershaft and motor.

    Frank.

  9. #9
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    Default

    Hi Frank,

    Thankyou for your post.

    I went with a wheel in preference to using a power tool, because whilst I can reverse the lathe motor and wind the saddle back quite quickly, you have very little control when tapping a hole, particularly with a small straight flute tap that very often is easily broken. Using the lathe wheel gives you feel and control which you don't get under power.
    Best Regards:
    Baron J.

  10. #10
    Join Date
    Oct 2008
    Location
    Cairns, Q
    Posts
    666

    Default

    Hi Baron,

    Fair enough. My ten inch countershaft pulley is reasonably accessible: I use it for tapping in the same way as you describe.

    Frank.

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