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Thread: Deep thoughts...metric threading

  1. #41
    Join Date
    Feb 2012
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    Metcalfe, Ontario, Canada
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    1,270

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    Quote Originally Posted by rickyb View Post
    And if your lathe, like my Logan, doesn't have a reverse?
    Reverse by pulling the belt. If you can't do that, use an open-end wrench on the chuck jaws. Or make a spindle crank. Better yet, have a reverse, by one means or another.
    Last edited by cameron; 04-13-2019 at 04:09 PM.

  2. #42
    Join Date
    Mar 2011
    Location
    Troy, Mi
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    129

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    Quote Originally Posted by cameron View Post
    Reverse by pulling the belt. If you can't do that, use an open-end wrench on the chuck jaws. Or make a spindle crank. Better yet, have a reverse, by one means or another.
    Then your way to go method isn't much of a way to go for me. I've tried this and it is untenable. Even with an electric drill jammed into back end of the spindle is a pita. I like Paul's crank idea andhopefuldave's drum switch.

    Threaded spindle limits my versatility of reverse unless I lock the chuck with a set screw of sorts. I now have a Magnetec 1 hp D.C. Motor and a Camco controller on the Logan. It is the single direction controller and can stop the spindle instantly. So much so that I spun a chuck off one time. I have to shut the power off and not use stop switch with a heavy chuck. I can easily get down to 2-3 rpm with this setup at near full hp. This slow speed and the brake will get me to a shoulder. Just need to add a switch to reverse the motor wiring.

  3. #43
    Join Date
    Jan 2004
    Location
    Missouri
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    30,990

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    Quote Originally Posted by Yondering View Post
    The "doesn't count" thing seems silly to me. Try doing the same thing without a thread dial; it's possible but a lot more difficult.

    As far as "just backing up" - disengaging the half nut allows you to thread up to a shoulder on lathes that don't have a brake (which most home shop lathes don't, look at the name of this forum). If you can't thread up to a shoulder, in most cases I use anyway, you can't thread at all.
    If you have to work to a customer print that calls for thread up "tight to" a shoulder, well OK. Feel free to charge the customer for a silly requirement that costs more to do.

    But if you are designing your own part, or are able to modify, then a small relief groove makes all the difference. It may be a better, stronger design as well.

    I rarely see a thread up to a shoulder anymore, they generally have relief grooves, because even in industry, it is easier and cheaper not to thread up tight to a shoulder, and it can be a poor design from a strength perspective.
    1601

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  4. #44
    Join Date
    Feb 2014
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    928

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    Quote Originally Posted by J Tiers View Post
    If you have to work to a customer print that calls for thread up "tight to" a shoulder, well OK. Feel free to charge the customer for a silly requirement that costs more to do.

    But if you are designing your own part, or are able to modify, then a small relief groove makes all the difference. It may be a better, stronger design as well.

    I rarely see a thread up to a shoulder anymore, they generally have relief grooves, because even in industry, it is easier and cheaper not to thread up tight to a shoulder, and it can be a poor design from a strength perspective.
    Yet another facepalm for Jerry.

    Of course there's a relief groove. If you thread at any reasonable speed above elderly walking pace and don't have a huge relief groove, you'll need to disengage the half nuts when threading up to a shoulder. I know you know this if you do any actual lathe threading, but of course you wanted something to argue about, again.

  5. #45
    Join Date
    Dec 2008
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    Kendal, On
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    1,558

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    If a part is designed for mass production it's cheaper to make it without the relief groove (just another feature that doesn't need to be there), as it will be done in a CNC and the machine doesn't care it there's a relief groove or not.

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