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Thread: First real part with my new CNC mill

  1. #11
    Join Date
    Jul 2009
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    Brighton, Michigan
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    Quote Originally Posted by John Stevenson
    John,
    Yep, that version works better, but still not quite as expected. At least this version doesn't continue with the former direction on the first reverse jog.
    What I am expecting is when I reverse directions with .001 jog, the stepper should turn enough to take up the backlash, plus the .001" with that first reverse jog. I don't get full backlash comp. until the second jog.
    Eric Sanders in Brighton, Michigan
    www.compufoil.com

  2. #12
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    Jan 2005
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    Surrey BC Canada
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    Eric,
    When you had the nut apart did you measure the balls? I am having issues with my new router and the ballscrews. Mine has 0.0065" lash. I did find an eBay vendor who sells balls of various sizes for 12 bucks per hundred. Most of the nuts seem to take 68 to 72 balls so a hundred lets you drop a few. ;-)
    Funny thing I I have bought some cheap screw assemblies from China off eBay and they seem to be almost zero lash. Go figure.
    It good a cleaning helped. Do you have any wipers on the screws? I imagine that keeping them clean will be important.

    Got any pictures of your coupler? Not following how it is running eccentric?
    I would imagine the Aluminum ones might be good. Are you talking about the ones that are three piece with a compliant cross in the middle?
    Glad to see you are using your machine.
    Dave

  3. #13
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    Quote Originally Posted by DFMiller
    Eric,
    When you had the nut apart did you measure the balls? I am having issues with my new router and the ballscrews. Mine has 0.0065" lash. I did find an eBay vendor who sells balls of various sizes for 12 bucks per hundred. Most of the nuts seem to take 68 to 72 balls so a hundred lets you drop a few. ;-)
    Funny thing I I have bought some cheap screw assemblies from China off eBay and they seem to be almost zero lash. Go figure.
    It good a cleaning helped. Do you have any wipers on the screws? I imagine that keeping them clean will be important.

    Got any pictures of your coupler? Not following how it is running eccentric?
    I would imagine the Aluminum ones might be good. Are you talking about the ones that are three piece with a compliant cross in the middle?
    Glad to see you are using your machine.
    Dave
    I didn't measure the balls and no wipers as of yet. I see some thick felt purchases in my future though.
    I didn't take any pictures of the coupler. I am talking about the three piece type.
    The rubber insert is like a four leaf clover shape. The stepper coupler side has two fingers and two more on the screw side. The fingers fit in between opposite sides between the clover petals if you will. If the fingers don't fit tight, the stepper and screws are not forced concentric to each other. I put the tape around the perimeter of the petals to take up the clearance.
    Eric Sanders in Brighton, Michigan
    www.compufoil.com

  4. #14
    Join Date
    Mar 2001
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    Nottingham, England
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    Eric
    Still on the road at the moment but look at Oldham couplings will post later
    .

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.




  5. #15
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    Surrey BC Canada
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    Eric,
    Those are the kind I was thinking about. They are like the ones I have ,but the compliant inserts are a press fit and not sloppy. The oldham couplers are similar. The oldham style seems to tolerate mis-alignment better since the insert seems to self align.
    There is always some fine tuning it seems.
    Dave

  6. #16
    Join Date
    Mar 2001
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    Nottingham, England
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    Just got back in.

    Those jaw type couplings are useless, they will only allow, not correct, for misalignment in one plane only and they take power to do this.

    The Oldham Coupling is the only non backlash coupling that will compensate for misalignment in two planes at the same time.

    http://www.youtube.com/watch?v=utEKKox2WHA
    .

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.




  7. #17
    Join Date
    Sep 2005
    Location
    Staffs, UK
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    Slightly off topic John, wheres best place to get decent leadscrews from? To replace or mod conventional mill.

    Incidently make by the hundred what OP posted, many in the US.
    As regards actual control of the Tasco, it will hinder it better off with standard larger wheel, gaps mean nothing!

  8. #18

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    I was not pleased with the Lovejoy couplings, but because they were part of the CNCfusion package I went with them. I would change to one of the spiral type if possible.

    On the Mach version note you have a smoothstepper, and backlash comp is new to smoothstepper. If you go back to the old Mach version Im not sure you can run the latest SS plug-in. see the smoothstepper site for some explanation of backlash. Note the one case you are doing, single .001 steps is exactly what the SS does not yet handle.
    ron ginger
    http://plsntcov.8m.com

  9. #19
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    Jul 2009
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    Quote Originally Posted by RonGinger
    I was not pleased with the Lovejoy couplings, but because they were part of the CNCfusion package I went with them. I would change to one of the spiral type if possible.
    Hi Ron,
    I checked out some of the spiral couplings available on eBay. The 1/4" end for the stepper is no problem, but the 5/16" screw end would need to be reamed. The biggest problem is the end to end height I am seeing is 25mm, while the lovejoys are 1-5/8" height. I need to look at it closer to see if it would cause any issues, but it appears that we would need to take off the .625" from the stepper mounting blocks.
    Eric
    Eric Sanders in Brighton, Michigan
    www.compufoil.com

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