New Build – NE Pennsylvania

New Home Forum Mostly Printed CNC – MPCNC Your Builds – MPCNC New Build – NE Pennsylvania

This topic contains 3 replies, has 2 voices, and was last updated by  Ryan 2 weeks, 4 days ago.

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  • #104392

    GaryH
    Participant

    In process of finishing a 16x26x4 MPCNC with a Mega2560/Ramps1.6 running dual endstop Marlin.  Std US EMT, Nema 17 64oz, 12V 20A power supply.  Parts are printed with PetG (Amazon Basics).  Hardware is mix of metric/standard determined by availability and pricing when I ordered.  bearings are all 608RS.  I made a couple of additions and am trying a set of belt tensioners from Thingiverse, an additional plate on the outside of the belt pulleys to provide a platform to fasten cable connections and some simple endstops I made.

    I am having discrepencies with the dual endstop action on the X axis – no consistency, repeatability when homing –  but can manually setup the device and produce the crown drawing.  Crown picture attached is the result of running the crown via CNCjs 4 consecutive times with each draw being separated by a move of both the X and Y axis a distance of 40 mm from home before beginning the next iteration.  Happy with the level of repeatability I an getting.

    Still have some more tape measure to add to direct the Z motor cable, gather more familiarity with EstlCam, CNCjs, etc.  Then I should be able to move on making noise and dust.

    #104430

    Ryan
    Keymaster

    I am having discrepencies with the dual endstop action on the X axis – no consistency, repeatability when homing

    What happens, did you set your drivers, how far off is your machine from square as it sits?

    #104547

    GaryH
    Participant

    Machine has a difference of 1/32 in on diagonal measure.  DRV8825’s are all in range 0.64 – 0.70.  I believe the frame is leveled and squared.

    Startup has involved – move arms till endstops are triggered,  power the mpcnc, confirm that X/Y axis are zeroed.  If I issue at G28 Y0, Y axis will move away form endstop and return to touch both endstops.  Movement of the 2 Y motors is in a synchronous movement and both make a soft landing against the endstops.   Issuing a G28 X0 also moves in a similar manner.  If I issue another G28 X0, the X arm moves away from the stops but the upper/left part of the arm drags behind the lower motor.

    I have tried changing the tension bolts to see if I can change this behavior but do not see any difference in the way it reacts.

    Future actions:    Re-measure and tunein the stepper Vrefs for X1/X2;  Replace the ZYX plates (I have reprinted these already;  Reprint and replace the XY cages;

    Any other suggestions?

     

    Attachments:
    #104549

    Ryan
    Keymaster

    By far the most common issue is a loose pulley.

    Try

    G28 X Y

    Don’t use the zero, no idea if that is good or bad but I never have.

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