Nozzle positoning problems



  • Hi to all. It looks i have a problem with nozzle positioning.
    I want to move delta robot head with vacuum pump to working limits and this is OK but the nozzle is not on the same height when it moves from lets say x250 to X-250.

    To be exact, distance between nozzle top at x250 is 69cm from floor and on -250 it's 70 cm.
    At X250 nozzle is in full horizontal line and on -250 it's slightly sloping toward X0.

    I have try to change the A values but it looks like it has nothing to do with it, because i have changed ratios in small and big scale ( just for test ). Shortly, nozzle head is moving "up and sloping" when it moves from 0 to -250. Ideas ?

    ;****FOR ROTARY DELTA SETUP
    ; B == bed radius = 1000mm
    ; H == Height--> distance between base center and floor --> 1800mm
    ; R == 15-5 = 5cm ( base centar --> motor shaft )
    ; A == arcsin /31
    ;------------------------------------------------
    M669 K10 U500 L1050 A-10:8 R8 H1800 B1000 ; A-10:7.3 / 9:8 / 8:7 / 10:5 etc
    M669 X150 Y150 Z150 ; rotate +X direction by 150deg
    M666 X0 Y0 Z0 ; Put your endstop adjustments here, or let auto calibration find them
    M574 X2 Y2 Z2 S0 ; END STOP SWITCHES



  • @Arnix_2

    Hi,

    Do you have a Z-probe on the machine?

    The delta calibration procedure can set those values based on probing the bed.

    Frederick



  • @Arnix_2 said in Nozzle positoning problems:

    I want to move delta robot head with vacuum pump

    what precision can be reached by those pumps?


  • administrators

    @Arnix_2 said in Nozzle positoning problems:

    Hi to all. It looks i have a problem with nozzle positioning.
    I want to move delta robot head with vacuum pump to working limits and this is OK but the nozzle is not on the same height when it moves from lets say x250 to X-250.

    To be exact, distance between nozzle top at x250 is 69cm from floor and on -250 it's 70 cm.
    At X250 nozzle is in full horizontal line and on -250 it's slightly sloping toward X0.

    To others reading this, please note it is a rotary delta.

    Consider XY points where the effector is moved out from the centre in line with one of the arms. Call these points A, B and C. Now consider points D, E, F which are opposite A, B and C (i.e. effector has moved out midway between a pair of arms). What you are saying is that the height at point A is not the same as the height at point D.

    Here are some possible causes:

    1. The parameters of your rotary delta machine are not quite right. This could include the homed arm angle, effective arm length, effective rod length etc. If this is the only cause, the height error will be symmetric. That is, the heights will be equal at A, B and C. They will also be equal at D, E and F, but not equal to the ABC height.

    2. The homing switches are triggering at different heights, and you have not compensated for that using M666. If that is the only cause, then the height errors will not be symmetric.

    3. Asymmetries in the machine construction will also cause non-symmetric errors, for example differences in the effective rod or arm lengths. If this is the cause, the effector will not stay level as it moves in the XY plane.

    So I suggest that you measure the height errors at points ABCDEF, and also put a circular spirit level on the effector so that you can see if it is tilting.

    PS - we don't yet have auto calibration for rotary delta printers, but maybe it would be useful to add. I envisage probing the 6 points ABCDEF and also the centre.



  • Thank you for your reply David. I will check all this in day or two.
    At the moment am adding new metal carriers for end switches so we will see if this may solve problem.
    They will be in mm with floor / construction / arms.

    A.


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