Duet3D Logo Duet3D
    • Tags
    • Documentation
    • Order
    • Register
    • Login

    "Endstop" accuracy

    Scheduled Pinned Locked Moved
    General Discussion
    5
    12
    432
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • gloomyandyundefined
      gloomyandy @fcwilt
      last edited by

      @fcwilt Stall detection works fine for me on my e3d toolchanger, I've never had any issues with pick up or drop off of tools. That's using TMC5160 drivers.

      1 Reply Last reply Reply Quote 1
      • jens55undefined
        jens55 @fcwilt
        last edited by

        @fcwilt, in my opinion, accuracy for homing for x and y are non issues. The only time where it would matter is if you had a power outage, lost reference to x and y and had to re-home. Other than that, since you wouldn't normally re-home in the middle of a print, I can't see why it would matter.

        gloomyandyundefined 1 Reply Last reply Reply Quote 0
        • gloomyandyundefined
          gloomyandy @jens55
          last edited by

          @jens55 As above for a e3d toolchanger (and probably others) the repeatability of homing is pretty important as the tool pickup mechanism requires fairly close tolerances. Probably not as close as needed to get a really good print with a power outage in the middle of it, but that's not something I've ever been concerned about (I can't remember the last time I had a power outage).

          @fcwilt The actual mechanics of homing between the two are interesting though. Although the detection with a switch is likely to be more easily detected, the print head can typically continue to move after the switch has triggered. If this overshoot is not the same each time, then the home position may not be as accurate as you may expect. A back off and rehome at a slower speed is often used to avoid this. However with stall detection the print head is typically hard up against the frame and so does not move any further (though I suppose it could bounce in some situations). One thing to check for though with stall detection is that when using something like corxy, both motors may not stall at the same point, this can lead the the print head "sliding" along the axis that it is stalling against which can result in the zero position of the "other" axis being lost. I've not seen this with my e3d set up, but have seen it with another corexy based printer.

          fcwiltundefined jens55undefined 3 Replies Last reply Reply Quote 1
          • fcwiltundefined
            fcwilt @gloomyandy
            last edited by

            @gloomyandy

            Thanks for the feedback.

            I can see where stall detection may provide better accuracy given it being hard up against the frame.

            Frederick

            Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

            1 Reply Last reply Reply Quote 0
            • jens55undefined
              jens55 @gloomyandy
              last edited by

              @gloomyandy said in "Endstop" accuracy:

              @jens55 As above for a e3d toolchanger (and probably others) the repeatability of homing is pretty important as the tool pickup mechanism requires fairly close tolerances.

              I don't know just how accurate you need to be for tool pickup but I am guessing that 1/2 of a mm is well within the range to still get good tool pickup. I would have thought (but don't know for sure) that stall detection gives better accuracy than that.
              For my Jubilee, x accuracy is the most important and I am guessing that + and - 0.5 mm from the optimal position being close enough for reliable pickup. Y accuracy can probably be within + and - 1 mm. Note that I never actually measured these tolerances but I set things up by eyeballing things.

              fcwiltundefined 1 Reply Last reply Reply Quote 0
              • fcwiltundefined
                fcwilt @jens55
                last edited by

                @jens55

                Yes the stall detection seems to work fine.

                Just to see if there was a difference I installed IR "beam break" detectors as endstop sensors on X and Y.

                Initial testing suggests that are not accurate enough to work well with the tool change feature.

                When I get some spare time I think I may try micro-switches.

                Thanks.

                Frederick

                Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

                1 Reply Last reply Reply Quote 0
                • fcwiltundefined
                  fcwilt @gloomyandy
                  last edited by

                  @gloomyandy

                  I thought stall detection was working fine but I spoke a bit too soon.

                  Here is my code for homing Y:

                  M98 P"wake_x_and_y.g"   ; energise motors to ensure they are not stalled
                  M400                    ; wait for any moves to complete
                  M913 X20 Y20            ; reduce stepper current
                  M915 X Y S0 R0 F0 H200 
                  G91                     ; relative moves
                  G1 H1 Y-310 F3000       ; move toward the Ymin "endstop"
                  G90                     ; absolute moves
                  G53 G1 Y0 F3000         ; move to the Y origin
                  M400                    ; wait for any moves to complete
                  M913 X100 Y100          ; reset stepper current
                  

                  Occasionally instead of moving according to the Y-310 value, it acts as if the value is Y310, and moves toward Ymax, instead of Ymin.

                  And, of course, there is no "endstop" defined for Ymax thus unpleasant, noisy things happen.

                  Any thoughts?

                  Thanks much.

                  Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

                  Phaedruxundefined 1 Reply Last reply Reply Quote 0
                  • Phaedruxundefined
                    Phaedrux Moderator @fcwilt
                    last edited by

                    @fcwilt said in "Endstop" accuracy:

                    Any thoughts?

                    @fcwilt said in "Endstop" accuracy:

                    M913 X20 Y20 ; reduce stepper current

                    Stepper current too low possibly.

                    Z-Bot CoreXY Build | Thingiverse Profile

                    fcwiltundefined 1 Reply Last reply Reply Quote 1
                    • fcwiltundefined
                      fcwilt @Phaedrux
                      last edited by

                      @Phaedrux

                      I took those values from some example code that dc42 posted quite some time back.

                      Perhaps time has shown they are too low.

                      I will test some more.

                      Thanks.

                      Frederick

                      Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

                      1 Reply Last reply Reply Quote 0
                      • Miss Rebekahundefined
                        Miss Rebekah
                        last edited by

                        Ae you testing this with the reported machine position or with an actual test indicator?

                        Im getting around +/- .0004(inches) with IR switch and +/-.0006 with clicky switch with roller lever. ten hits discarding the lowest and highest avg the rest, with a brown and sharp 50 millionths test indicator (inches) it was calibrated 5 months ago. first touch was 3000mm/min second @100mm/min. i dont care what the machine says its at the indicator doesn't lie.

                        I don't do sensorless homing running your machine into a wall to home it just doesn't seem like a good idea to me.

                        I want to make a tester with an as5600, esp32 and a little lcd to keep track of the rotations as sort of a lost steps checker i can slap on if i suggest shennanigans are afoot if i zero it at x0y0 print go to x0 y0 it should read 0

                        either switch is accurate enough for a toolchanger. btw real cnc mills have about 5-10 of the clicky type switches in the actual tool changer mechanisms to tell the control where everything is at incase something doesn't get where it needs to be on time the tool change cycle will alarm out and stop before it starts self disassembly.

                        your not really after accuracy you want repeatability. if it repeats accuracy is the easy part.

                        fcwiltundefined 1 Reply Last reply Reply Quote 0
                        • fcwiltundefined
                          fcwilt @Miss Rebekah
                          last edited by

                          @Miss-Rebekah

                          Thanks for that most informative post.

                          Frederick

                          Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

                          1 Reply Last reply Reply Quote 0
                          • First post
                            Last post
                          Unless otherwise noted, all forum content is licensed under CC-BY-SA