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    An alternative to z-hops for delta kinematics

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    • dc42undefined
      dc42 administrators
      last edited by

      I had a similar idea 2 or 3 years ago, although my plan was to split the move into 2 parts with a greater Z coordinate at the join. Or possibly use a single move with a quadratic Z term added.

      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

      Naqajundefined 1 Reply Last reply Reply Quote 0
      • Alexander Mundyundefined
        Alexander Mundy
        last edited by

        Hope I understand correctly what you are contemplating. Kisslicer has an option to curve the start and stop of a zhop. I've found (I print with PETG most of the time) that it doesn't cleave (for want of a better word) the filament as well as a straight up zhop so leads to stringing easier.

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        • abeckerundefined
          abecker
          last edited by

          The new version of KISSlicer actually has this as an option so there may be something to it.
          0_1547231530034_arc.png

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          • Edgars Batnaundefined
            Edgars Batna
            last edited by

            This "Arc" Z-hopping would be interesting to try on any kinematics.

            dragonnundefined 1 Reply Last reply Reply Quote 0
            • dragonnundefined
              dragonn @Edgars Batna
              last edited by

              @edgars-batna said in An alternative to z-hops for delta kinematics:

              This "Arc" Z-hopping would be interesting to try on any kinematics.

              Yeah I agree, regular z-hop increases stringing (especial on bowden systems) the arc solution could be better in that meter. And it would require less fast z-axis then regular z-hop.
              Would be nice to see that implemented in firmware retraction on Duet.

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              • Naqajundefined
                Naqaj @dc42
                last edited by

                @dc42 said in An alternative to z-hops for delta kinematics:

                I had a similar idea 2 or 3 years ago, although my plan was to split the move into 2 parts with a greater Z coordinate at the join. Or possibly use a single move with a quadratic Z term added.

                Do you have any plans for revisiting this?

                @edgars-batna said in An alternative to z-hops for delta kinematics:

                This "Arc" Z-hopping would be interesting to try on any kinematics.

                Certainly, though the point here was that a delta may provide this in an easier way to implement, simply through timing and without additional movement.

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                • DeltaConundefined
                  DeltaCon @Naqaj
                  last edited by

                  @naqaj said in An alternative to z-hops for delta kinematics:

                  ...i was thinking about an alternative to using z-hops that would avoid the extra g-code, interruption of movement, and maybe reduce the need for retraction for travel moves across a print surface.

                  What in your opinion would be the benefit of that, except for the savings in gcode? The only benefit of a delta regarding Zhop is that it can do that REALLY fast compared to a moving bed. The benefit there is that, if tuned right, it can Zhop so fast that it breaks the string BEFORE the nozzle moves in the XY-plane. Besides that zhop-less movements are less stringy than moves with zhop, any technique that moves in XY during zhop would in my view INCREASE stringyness.

                  If you think trial and error is dangerous, try routine. That's even more so!

                  Alexander Mundyundefined Edgars Batnaundefined 2 Replies Last reply Reply Quote 0
                  • Alexander Mundyundefined
                    Alexander Mundy @DeltaCon
                    last edited by

                    @deltacon said in An alternative to z-hops for delta kinematics:

                    @naqaj said in An alternative to z-hops for delta kinematics:

                    ...i was thinking about an alternative to using z-hops that would avoid the extra g-code, interruption of movement, and maybe reduce the need for retraction for travel moves across a print surface.

                    ......The only benefit of a delta regarding Zhop is that it can do that REALLY fast compared to a moving bed. The benefit there is that, if tuned right, it can Zhop so fast that it breaks the string BEFORE the nozzle moves.......any technique that moves in XY during zhop would in my view INCREASE stringyness.

                    That has been my experiance trying arc z hop in Kisslicer, stringing that I don't get with regular z hop.

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                    • Edgars Batnaundefined
                      Edgars Batna @DeltaCon
                      last edited by

                      @deltacon Can you elaborate on "REALLY fast"? My bed and travel are very fast on my CoreXY, it pains me to watch them waiting for eachother.

                      DeltaConundefined 1 Reply Last reply Reply Quote 0
                      • DeltaConundefined
                        DeltaCon @Edgars Batna
                        last edited by DeltaCon

                        @edgars-batna
                        Since the buildplate does not move on a delta, there is very little mass involved in a Z move. Besides that the mass is moced by 3 stepper motors simultaneously. All three arms move up identically during a Z hop. Most CoreXY printers use leadscrews which move the bed pretty slow and certainly not quick enough to snap the thread. On my Rostock I've set Z-move to 10.000 or something. It is probably limited by other factors, but it gives a real good "Clunck" sound at each retraction 😉

                        If you think trial and error is dangerous, try routine. That's even more so!

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