just received an acme screw and delrin nut.. Question about tightness


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Thread: just received an acme screw and delrin nut.. Question about tightness

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    Default just received an acme screw and delrin nut.. Question about tightness

    The delrin nut seems to turn pretty easily on the screw until maybe 5 turns in, where it becomes pretty hard to crank by hand.

    How tight should it be?
    Should I be able to turn it by hand without putting much effort?

    Thanks

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    Quote Originally Posted by blau_schuh View Post
    The delrin nut seems to turn pretty easily on the screw until maybe 5 turns in, where it becomes pretty hard to crank by hand.

    How tight should it be?
    Should I be able to turn it by hand without putting much effort?

    Thanks
    If the No indicates Norway my (not serious) suggestion is wait for summer; Delrin has a large coefficient of thermal expansion.



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    Registered tager_rot's Avatar
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    As a rule of thumb that I adopted when building my cnc.... If I could not turn the lead screw with my thumb, index and middle finger (on my 5/16" nut and while it was fully assembled with the motor attached) then I would fine tune that axis more. I found that if I couln't trun it that way my 269 oz. stepper that was attached "in-line" with the lead screw would stall. At least that is what I experienced.


    Justin!!!



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    Registered planekrazie's Avatar
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    Small question about Geofs coment. Now I understand why my leadnut is stalling out my steppers in the cold mornings. I have to heat up my building for 1 hr to jog my router. Could this be the problem. Oh yea I am using UHMW lead nuts. ( homemade)
    Steve


    Quote Originally Posted by Geof View Post
    If the No indicates Norway my (not serious) suggestion is wait for summer; Delrin has a large coefficient of thermal expansion.




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    Quote Originally Posted by tager_rot View Post
    As a rule of thumb that I adopted when building my cnc.... If I could not turn the lead screw with my thumb, index and middle finger (on my 5/16" nut and while it was fully assembled with the motor attached) then I would fine tune that axis more. I found that if I couln't trun it that way my 269 oz. stepper that was attached "in-line" with the lead screw would stall. At least that is what I experienced.


    Justin!!!
    Hmm, I just got a replacement delrin nut from the seller. same thing. REALLY TIGHT! I basically need to grab the delrin nut as if I'm gribbing an orange and crank at it. at least there is no backlash

    what do you mean by "fine tune"?



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    Quote Originally Posted by planekrazie View Post
    Small question about Geofs coment. Now I understand why my leadnut is stalling out my steppers in the cold mornings. I have to heat up my building for 1 hr to jog my router. Could this be the problem. Oh yea I am using UHMW lead nuts. ( homemade)
    Steve
    whats UHMW?



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    Registered mxtras's Avatar
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    UHMW = Ultra High Molecular Weight Polyethylene - "poor man's teflon". Cruise around on www.mscdirect.com - they have UHMW, Acetal, HDPE - all kinds of plastics and they sell small quantities.

    EDIT - Try www.mcmaster.com instead - they have a much better selection for raw materials.

    EDIT - Or try this site - it's a bit slow, but there is a large variety of plastics - www.professionalplastics.com

    Scott

    Last edited by mxtras; 12-06-2006 at 12:10 AM. Reason: Added another link
    Consistency is a good thing....unless you're consistently an idiot.


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    Registered planekrazie's Avatar
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    Now I see why its a poor mans teflon. It liks to freeze up in cold weather causing my steppers to stall. What to do, What to do. How bout rack and pinion?



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just received an acme screw and delrin nut.. Question about tightness

just received an acme screw and delrin nut.. Question about tightness