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  1. #41
    cheers no worries i have been advised that its been better to drive the ball screws with separate motors but then wired together so id there is any interference on start up the same goes to booth so not to sure now. I liked the idea of just bolting the motors straight up to the ball screws without having all sorts of belts and pulleys but having just the one motor would make some things easier. Another job this week is figuring out the x axis drive and what ratio i need to gear the stepper to.

  2. #42
    Well who ever told you that is wrong.!! Problem comes from Mid band resonance and how the drive works out compensation and correction. When you have 2 motors connected to one drive it doesn't know which motor to apply the compensation correction to so it can throw the other motor into resonance.

    I can tell you from experience that screws connected with belts are by far the best option and most accurate with least hassle other than attaching pulleys.

  3. #43
    ok cool i will try work that into the design. is there a standard method for doing the belts i couldn't find much when looking last week?

  4. #44
    Quote Originally Posted by charlieuk View Post
    ok cool i will try work that into the design. is there a standard method for doing the belts i couldn't find much when looking last week?
    No real standard way regards laying out as it's often machine dependant but regards sizes etc then there is kind of standard in that most use in HTD 5mm pitch belts and either 15 or 25mm wide. Pulley sizes will depend on if your having a ratio but from experience between 18-20T for 1:1 ratio is best. If you go too small you risk excessive wear and jumping teeth due to fewer teeth being engaged. Equally don't go too large on pulley size as the extra inertia will have a negative affect.

    Really this is something you should have worked out before ordering the ballscrews as you could have had the screws machined in such away that they suited pulleys and made life easier.

  5. #45
    ok many thanks for that. is it best to drive one screw direct with the motor and then take a belt of that to the other side or have the motor central and run two belts to ether side or is there another way? i could do with keeping all the motors and belts down to the one end if posable.

  6. #46
    Last edited by EddyCurrent; 06-05-2014 at 02:46 PM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  7. #47
    found this on google turns out i was searching the wrong name

    is this the sort of thing i need to do? I only have 265mm between the centres of the ball screws ether side so the belt wont need to be that long
    Last edited by charlieuk; 28-11-2014 at 12:36 AM.

  8. #48
    Ah ah think I drew that for someone on here long time ago when I used Rhino.!! . . . If not I've done something very similair for someone.

    But yes that type of thing thou in your case I'd just offset the motor to one side for ease of build and neatness. Doesn't matter if it's offset with such a short belt.

  9. #49
    cool that should be fairly simple then as i can get a pulley straight on the shaft and motors, i may have to put a extra pice of extrusion across anyway to take the motor mount so not sure go off centre is going to make it to much neater, i think i have a little ocd on things being symmetrical as well.

    What i will also do is try and get the bk and bf blocks in line with the top of the alli so the stepper does not drop to far bellow the gantry. I would have loved the belt and motor to be all inside but that doesn't look possible with this design.

  10. #50
    Jazzcnc, thanks for that, I've been thinking what's best for this kind of setup, too.
    Helluva build, eh?

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