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Controlled arc problem

Scheduled Pinned Locked Moved Solved
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  • undefined
    neilo
    last edited by 31 Dec 2020, 08:20

    @dc42 Hi there I'm using RRF 3.1.1. Is it worth giving the latest version a go? (3.2)

    @alankilian I'll try some other moves in the meantime today 🙂

    Cheers

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    • undefined
      dc42 administrators
      last edited by 31 Dec 2020, 22:39

      Yes, please try firmware 3.2RC2.

      Duet WiFi hardware designer and firmware engineer
      Please do not ask me for Duet support via PM or email, use the forum
      http://www.escher3d.com, https://miscsolutions.wordpress.com

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      • undefined
        neilo
        last edited by 2 Jan 2021, 07:55

        @dc42 sorry it's not clear to me whether I can go direct from 3.1.1 to 3.2 RC2? The RC2 release notes say the iap files have not changed since RC1 but cannot see them in the RC1 area to copy across.

        Also RC1 notes state: "Users of Duet + Single Board Computer should upgrade from the packager server as usual." Not clear to me where/what the package server is!

        Thanks,
        Neil

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        • undefined
          Phaedrux Moderator
          last edited by 2 Jan 2021, 18:34

          https://github.com/Duet3D/RepRapFirmware/releases/tag/3.2RC1

          There are 4 files with SDiap32 in their names.

          https://duet3d.dozuki.com/Wiki/Getting_Started_With_Duet_3#Section_Software_Installation

          You can find the instructions for adding the unstable branch package server here.

          Z-Bot CoreXY Build | Thingiverse Profile

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          • undefined
            neilo
            last edited by 3 Jan 2021, 19:36

            Thanks very much for your assistance, the good news is that the firmware upload (RRF3.2RC2)went fine, the bad news is that the mis-behaviour is still present.
            For example a simple square is not completing (fig 1) WIN_20210103_19_24_45_Pro.jpg
            or a sequence of simple moves (fig 2)WIN_20210103_19_25_08_Pro.jpg .
            This time I've uploaded the config and gcode files for the above if someone could please spot the deliberate mistakeconfig.g
            arc.g
            squaretest.g

            undefined 1 Reply Last reply 4 Jan 2021, 19:19 Reply Quote 0
            • undefined
              whopping pochard
              last edited by 3 Jan 2021, 20:23

              Your 'squaretest' file has only G1 moves, right? Are you sure you aren't missing steps due to a mechanical or electrical problem?

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              • undefined
                cjm @neilo
                last edited by 4 Jan 2021, 19:19

                @neilo

                I've used a Duet 2 board running RepRapFirmware for Duet 2 WiFi/Ethernet 3.2-beta1 (2020-09-15b1) with a homebrew CNC to machine a test piece containing diamond, circle and square sections:

                SquareDiamondCircle.jpg

                The g-code for this with a 5mm diameter end mill is as follows and contains both G2 and G3 commands that the Duet appears to have executed correctly:

                SquareDiamondCircle 42mm.g

                The finishing passes for the circular section are complete circles so one assumes should have shown up the same sort of error you're seeing if this was intrinsic to the Duet hardware/firmware?

                Perhaps trying this g-code file might help diagnose the problem?

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                • undefined
                  neilo
                  last edited by 4 Jan 2021, 19:22

                  @whopping-pochard that's right just trying to keep it simple with G1 commands in one file. I've added another test (fig 3)fig3.jpg
                  and it appears to act erratically. Mechanically it looks fine, it's belt drive on X and Y NEMA 23 FYI .
                  steps.g

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                  • undefined
                    neilo
                    last edited by 4 Jan 2021, 19:23

                    @cjm just seen your post - many thanks I will try it out tomorrow.

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                    • undefined
                      neilo
                      last edited by 6 Jan 2021, 11:13

                      @cjm here is the result: Still looks weird and clearly incorrect. I used a 1/4 inch bit so slight dimensional difference but does not explain for me the strange behaviour.
                      Would you mind sharing your config.g file with me please?
                      WIN_20210106_11_07_32_Pro.jpg
                      Thanks,
                      Neil

                      undefined 1 Reply Last reply 6 Jan 2021, 13:23 Reply Quote 0
                      • undefined
                        droftarts administrators @neilo
                        last edited by 6 Jan 2021, 13:23

                        @neilo I think this is a mechanically issue. My best guess is that the X pulley is slipping on the motor shaft, because the first move of any change in direction in X causes the movement error, but subsequent ones do not. Probably the grub screw on the pulley is loose, allowing a limited range of movement.

                        Ian

                        Bed-slinger - Mini5+ WiFi/1LC | RRP Fisher v1 - D2 WiFi | Polargraph - D2 WiFi | TronXY X5S - 6HC/Roto | CNC router - 6HC | Tractus3D T1250 - D2 Eth

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                        • undefined
                          sonderzug
                          last edited by 6 Jan 2021, 13:40

                          I second @droftarts opinion; circles with horizontal and vertical flat spots (i.e. corresponding to the direction change of the x respectively the y axis) indicate mechanical backlash, quite noticable in your case.

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                          • undefined
                            alankilian
                            last edited by 6 Jan 2021, 15:14

                            One way to test this theory is to make a square, but rotated 90-degrees.

                            That way, you get two reversals of each axis while the other axis is moving continuously in the same direction.

                            You'll see the vertices get messed up if you've got a lot of backlash.

                            AND you can do it with just G1 moves.

                            SeemeCNC Rostock Max V3 converted to V3.2 with a Duet2 Ethernet Firmware 3.2 and SE300

                            undefined 1 Reply Last reply 6 Jan 2021, 15:17 Reply Quote 0
                            • undefined
                              droftarts administrators @alankilian
                              last edited by 6 Jan 2021, 15:17

                              @alankilian said in Controlled arc problem:

                              One way to test this theory is to make a square, but rotated 90-degrees.

                              Don't you mean 45 degrees?!

                              Ian

                              Bed-slinger - Mini5+ WiFi/1LC | RRP Fisher v1 - D2 WiFi | Polargraph - D2 WiFi | TronXY X5S - 6HC/Roto | CNC router - 6HC | Tractus3D T1250 - D2 Eth

                              undefined 1 Reply Last reply 6 Jan 2021, 19:32 Reply Quote 1
                              • undefined
                                neilo
                                last edited by 6 Jan 2021, 18:48

                                Thanks folks for the opinions really appreciate independent advice! I will focus on the mechanicals and re-test the square / diamond combo.
                                Neil

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                                • undefined
                                  alankilian @droftarts
                                  last edited by 6 Jan 2021, 19:32

                                  @droftarts said in Controlled arc problem:

                                  Don't you mean 45 degrees?!

                                  Ha ha.

                                  Yes. Thanks for catching my lack-of-coffee posting.

                                  SeemeCNC Rostock Max V3 converted to V3.2 with a Duet2 Ethernet Firmware 3.2 and SE300

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                                  • undefined
                                    cjm
                                    last edited by cjm 1 Jun 2021, 20:52 6 Jan 2021, 20:37

                                    @neilo The behaviour does look odd.
                                    It is interesting that some of the part (e.g. the upper left quadrant) is machined OK over multiple layers.
                                    As mentioned by others, this implies something is loose, perhaps a drive block, so that when the axis is driven in one direction the slack is taken up and the movement is controlled, but when there is a change of direction, the slack needs to be taken up in the other direction before movement control is restored. i.e. backlash, but with much more movement (around 4-5mm by the looks of the part) than normal.
                                    With the spindle/router powered down and unplugged for safety, if you send the machine to XY coordinates in the middle of its range and then manually try move the spindle/axes carriages in X and Y directions what do you feel?
                                    Everything should be tight, with no knock or play.

                                    I'm not sure it will help but as requested here's my config.sys file:
                                    config.g

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                                    • undefined
                                      alankilian
                                      last edited by 6 Jan 2021, 22:22

                                      This seems like a big enough error that you should be able to measure it with a ruler.

                                      Try:

                                      g0 x0 y0
                                      (Mark the position)
                                      g0 x100
                                      (Check to see if it moved 100mm)
                                      g0 x0
                                      (Check to see if it moved 100mm back)

                                      If there's a lot of backlash in the X mechanics, you'll see one or the other of those moves be less than 100mm

                                      SeemeCNC Rostock Max V3 converted to V3.2 with a Duet2 Ethernet Firmware 3.2 and SE300

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                                      • undefined
                                        neilo
                                        last edited by 9 Jan 2021, 13:57

                                        Dear all, thanks so much for the advice, the loose grub screw was the root cause which was definitely in my blind spot! Learnt a lot and really appreciate the support, looking much better now with some tweaks.
                                        Neil
                                        WIN_20210109_13_55_44_Pro.jpg

                                        undefined 1 Reply Last reply 10 Jan 2021, 00:06 Reply Quote 4
                                        • undefined
                                          whopping pochard
                                          last edited by 9 Jan 2021, 14:07

                                          Hooray!! Glad you solved it!

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