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    Default Preferred lead angle ignoring all other factors.

    Hi,
    Sorry if this has already been discussed to death.

    Let's say things like critical speed, motor selection, cost, etc are ignored and any differences in travel speed and resolution are made equal using gearing between the motor and the ball screw. Is there any significant difference in accuracy or backlash between a lower lead angle ball screw vs a higher lead angle ball screw? Could you get the same results from a 20mm angle screw geared to half servo speed vs a 10mm angle screw at 1:1 servo speed. Ignoring critical speed, why choose one over the other if gearing can make up for the differences?

    I ask because I'd like to build a 4'x4' router with fast rapids (~1200IPM). The most common choices for ball screws appear to be 2510 and 2525 sizes. If I go with 2510s I will likely encounter screw whip (~3048rpm) so I'd probably go with a rotating ball nut. On the other hand, if I go with 2525s I can gear down the servos and screw whip isn't an issue (~1212rpm). Either way I'm using a belt. The 2525s with gearing sound good but I feel like there has to be a catch. For what it's worth, I'm eyeing the ClearPath nema 34 servos and planning on a steel gantry. Planning to cut wood, plastic, and aluminum.

    Thoughts?

    Thanks

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  2. #2
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    Default Re: Preferred lead angle ignoring all other factors.

    The faster you spin the screw, the faster it'll wear out.
    And you can't ignore critical speed, as it dictates how fast you can spin the screw.
    Also, screw manufacturers will tell you that the critical speed does NOT change when you spin the nut.

    With servos, I'd go for the highest lead possible. With steppers, it's trickier, because you have to juggle speed vs resolution.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: Preferred lead angle ignoring all other factors.

    I don't see any reason why not to go with a 2520 or 2525. The major downsides to higher lead are higher torque, and of course probably either not being able to do direct drive, or needing a high-inertia servo. Which motor are you looking at?



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Preferred lead angle ignoring all other factors.

Preferred lead angle ignoring all other factors.