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  1. #16
    Join Date
    May 2015
    Location
    Richmond
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    214

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    Quote Originally Posted by Alf Scotting View Post
    O.K. guys,thanks for your input none of which has solved my problem - I was going to ask Steve if we could talk as he has the same lathe as mine but no change gears so obviously can't cut threads - I have triple checked my settings with my change gears and as I am cutting a stud without a runout groove I always retract the tool at the end and reverse the rotation direction - I just put a 20mm. piece of brass in the chuck, engaged the half nut and took a cut which gave me a groove of about 40 TPI ???My manual tells me the gear engaging the leadscrew is 24T and the panel near the halfnut engagement lever has underneath 24 the letter 'E' so I engaged at 'E' but still get 40ish TPI
    I have cut threads in the past without any problem so keep thinking I have missed something but can't think what it would be - keep thinking please fellers The calculation by old rusty toolie , I can't see its relevance to my problem
    Hi Alf. This is in your opening lines "The thread chasing dial shows 24,21,20 and 18 and the appropriate alphabetical position to engage the dial - I cant understand why I cant engage anywhere as the sprocket engaging the leadscrew (24T) engages the fixed TPI leadscrew - does the fact that the chasing dial has only the numbers above mean I can only engage 24,21, 20 or 18 TPI? I am sure I haven't had this problem before so maybe I'm missing something?" Later you mention that it is in fact a metric leadscrew.

    The relevance of the calcs was for the tracking problems which exist when cutting imperial on metric lathes and metric on imperial lathes. The 6mm leadscrew was just a sample. As you have two "threads" going on the same subject it starts to get confusing. Maybe better off locking that other one and continuing here.

    To find why you are cutting around 40 tpi when it should be 16tpi you will have to give the full story. We now know that your leadscrew is 4mm but what gears are available and what is shown on a chart to convert a selected lead on your qc gearbox to cut a 1/16" lead. Until then, we are just guessing what the problem is.

    Rusty

  2. #17
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
    Posts
    2,651

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    Hi Alf,

    This is the chart from mine. Is yours the same?

    If I'm reading it right - mine would be 50 50 126 Gearbox #1 and B

    IMG_3510 (Large).jpg


    Steve

  3. #18
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,444

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    Quote Originally Posted by OxxAndBert View Post
    Hi Alf,

    This is the chart from mine. Is yours the same?

    If I'm reading it right - mine would be 50 50 126 Gearbox #1 and B

    IMG_3510 (Large).jpg


    Steve
    I would concur ! I would check that those are the gears that are actually in play.
    On my Myford there is a provision for a super fine feed, which requires a gear to be swapped.
    If I don't do that swap the gear change chart is garbage.
    Best Regards:
    Baron J.

  4. #19
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

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    Quote Originally Posted by BaronJ View Post
    On my Myford there is a provision for a super fine feed, which requires a gear to be swapped.
    If I don't do that swap the gear change chart is garbage.
    Same on my Hercus 260.
    Chris

  5. #20
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

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    Hi Rusty and gentlemen,
    Attached photos are of the chartsimage006.jpg on my laimage004.jpgthe as proimage003.jpgmiseimage002.jpgd -still don't know where I am going wrongimage001.jpg

  6. #21
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
    Posts
    4,887

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    Your chasing dial and chart are not required, as said previously leave the half nuts engaged and just reverse.
    Is the gear train set correctly.

  7. #22
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
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    2,651

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    An earlier post stated that the gears were set to 72 68 30 120 so that would seem OK to me.
    Its a later model than mine (which is 1987). Looks nice BTW

    Getting 40tpi when set to cut 16tpi it almost seems like its in feed mode. From a general troubleshooting aspect, I'd suggest trying to cut something like 10tpi and see what happens and if there looks like a pattern (ie still roughly 3x too fine).

    Steve

  8. #23
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

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    yes, triple checked - I think I have found the problem ,will check after breakfast - the lever in image002 should be to the left?
    will report back and hopefully close thread

  9. #24
    Join Date
    Jul 2013
    Location
    BRISBANE BAYSIDE
    Posts
    90

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    According to your chart, for imperial threads, both the levers in images 002 & 003 should be on the left.

  10. #25
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

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    Tried that - no difference - I have sent off an email to Takisawa, let's see if we get an answer. maybe there is a problem with the gearbox?

  11. #26
    Join Date
    Dec 2013
    Location
    Sydney
    Posts
    201

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    "No difference" This is a clue. Moving those levers should always lead to a different pitch. Are you sure you are not engaging the lever for feeds, instead of the half nuts for threading?

    Graham.

  12. #27
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

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    O.K. Rusty,
    Have done your calc. relative to my lathe and have a result of 508 - what does that do for me and where did you get your 127 over 5 from?
    have tried everything else even sent an email to Takisawa - let me have your ph. No. by private message and I will call you to discuss
    Alf

  13. #28
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

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    Not so - when I do that I can only get the traverse shaft rotating

  14. #29
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

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    Not possible - there is a lockout on my lathe where you can't engage traverse when you are trying to cut threads

  15. #30
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

    Default

    If I do that only the traverse shaft rotates , not the leadscrew

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