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  1. #1
    For a single CENTRALLY DRIVEN gantry I would not go wider than 600mm. Any wider needs to drive systems (one on each side). Yours looks considerably wider.

    Furthermore, and critically, for your design it is very unusual to try and drive a gantry from one side only. It is very likely to rack / judder, plus give poor accuracy when cutting further from the driven side.

    I expect that if you grab hold of the non-driven side you can push it back and forth several mm, maybe more ? If so racking is a the likely cause of the judder.

    This can be reduced by spacing the X axis bearings further apart fore/aft, but I suspect even this may not be enough if you are still driving from one side.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  2. #2
    yea its what i have been thinking all along. its nearly 1600 on the x axis so i was just pushing my luck. to add another drive on is that the A axis that is used???

  3. #3
    Clive S's Avatar
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    Quote Originally Posted by Davo242 View Post
    yea its what i have been thinking all along. its nearly 1600 on the x axis so i was just pushing my luck. to add another drive on is that the A axis that is used???
    I don't think you will ever get it working with those drives and a 36V power supply and one motor on the long axis. Also do you have a gearbox on the rack & pinion what is the ratio.
    ..Clive
    The more you know, The better you know, How little you know

  4. #4
    no gear box just a direct drive at the min for testing. its a 59 tooth sprocket on a mod1 rack. 4:1
    Last edited by Davo242; 06-01-2016 at 03:49 PM.

  5. #5
    Quote Originally Posted by Davo242 View Post
    no gear box just a direct drive at the min for testing. its a 59 tooth sprocket on a mod1 rack. 4:1
    What you mean 4:1 if it's direct drive there's no ratio.? 59T direct drive means 185mm pitch.!!!

    Anyway I strongly advise you to STOP and have re-think because your wasting your time on several fronts.
    #1 No way can you move gantry that wide with one motor.
    #2 Ratio of at least 5:1 will be needed with that size pinion.
    #3 The drives are rubbish and even with 36V if they survive long enough they will run so badly and rough you'll struggle even with 2. This is because resonance will cripple them and turn them into horrible stalling nightmares. These cheap nasty drives have no way of dealing with resonance and with machine being all steel and not exactly HD the motors/drives will be affected.
    #4 Looking at the Z axis unless your going to use for just Plasma then No way is that Z axis going to be upto cutting anything but foam. Certainly won't cut wood very well.

    So again please don't take this wrong way I say it for your own sake and your wallets sake. You'll be wasting good money and time if you continue as you are.!

  6. #6
    what do u see wrong with the z axis jazz??

  7. #7
    Quote Originally Posted by Davo242 View Post
    what do u see wrong with the z axis jazz??
    Single bearings on the rails. Rails not on front plate so bearings are miles from the cutter. Spindle mounted at wrong end.

    In fact simply taking the Z-axis front plate off with the bearings and turning it upside down would make a difference...
    Old router build log here. New router build log here. Lathe build log here.
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  8. #8
    Quote Originally Posted by Davo242 View Post
    what do u see wrong with the z axis jazz??
    Jonathan said everything that needed to be said so I won't repeat.

    But I will say this.!!. . . The fact you have asked this question to me and query what jonathan points out plus the fact you have bought TB based drives and no clue about voltage shows me you haven't done much research so I suggest you start doing some.
    We can tell you this and that, answer a query or two but you really need to read up on it and under stand why things are done like they are. Doing so will save you money and time in the long run.

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