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    Question on Z-Offset and Start Script, Also Nozzle Adjustment.

    Scheduled Pinned Locked Moved
    Tuning and tweaking
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    • Phaedruxundefined
      Phaedrux Moderator
      last edited by

      Did you correct the PT1000 configuration for heater 1 as mentioned above? That could easily explain why you're 20 degrees off expected.

      Z-Bot CoreXY Build | Thingiverse Profile

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      • justinds89undefined
        justinds89 @Phaedrux
        last edited by

        @phaedrux

        I didn't change anything as my configuration has this set for heater 1:

        M305 P1 X200 ; Configure thermocouple for heater 1
        M143 H1 S280

        I thought this was correct?

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        • justinds89undefined
          justinds89 @Phaedrux
          last edited by

          @phaedrux

          I should note I have a PT100 connected to the daughterboard.

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          • Phaedruxundefined
            Phaedrux Moderator
            last edited by Phaedrux

            Ah I see. Earlier you had said pt1000. Easy typo to make. I wish they had slightly different names.

            The link I posted earlier for PID tuning has a lot of information but basically start from a cold machine and run the M303 command with the parameters for the heater you want to tune.

            https://duet3d.dozuki.com/Wiki/Gcode#Section_M303_Run_heater_tuning

            M303 H1 S220 ; tune hot end to 220c
            M303 H0 S60 ; tune bed to 60c

            After they are finished you can send M500 to save the values to config-overide so they are loaded at startup, or send m303 again with no parameters Send M307 H1 and it will report the PID values it found for heater 1 which can manually be entered into config.g. it's easier to just use m500 and then copy and paste the values over if you wish. M307 H0 will give the results for the heated bed.

            Z-Bot CoreXY Build | Thingiverse Profile

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            • justinds89undefined
              justinds89 @Phaedrux
              last edited by

              @phaedrux

              Sorry for the confusion.

              As I understand I need to just run the M303 command? I don't need to plug in specific values?

              Appreciate all the help. Getting closer to having this up and running!

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              • Phaedruxundefined
                Phaedrux Moderator
                last edited by

                M303 H1 S220 The H1 tells it to tune heater 1 which is the hotend, and to target 220c as the temperature. The tuning will give some messages about what it's doing in the console. It will heat up and cool down the hotend which can take 10 or more minutes. When it's done you can send M307 H1 and it will tell you the values it came up with for heater 1. Then send M500 to save the values.

                Z-Bot CoreXY Build | Thingiverse Profile

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                • justinds89undefined
                  justinds89 @Phaedrux
                  last edited by

                  @phaedrux

                  Ah okay, I will try this tonight!

                  Thanks again.

                  I will post back if it helped or not.

                  I'm assuming I'm good to go as soon as I get this temp issue sorted.

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                  • Phaedruxundefined
                    Phaedrux Moderator
                    last edited by

                    PID tuning will help the temperatures be more stable, but won't account for being off by 20 degrees.

                    Definitely keep an eye on the temperature graph as it transitions from the first layer to the next. Does the set temperature get lowered? That would indicate that the slicer has a too low temp set for later layers.

                    Z-Bot CoreXY Build | Thingiverse Profile

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                    • justinds89undefined
                      justinds89
                      last edited by

                      It looks like my cooling fan is dropping the temperature of the nozzle down for a little bit before it picks back up and stabilizes.

                      I take it at this point I need to figure out a way to direct the cooling more downward away from the nozzle and heat block?

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                      • Phaedruxundefined
                        Phaedrux Moderator
                        last edited by

                        You have 3 options, choose any or all.

                        1. Find a better cooling shroud that can direct the airflow better.
                        2. Insulate the hotend block in some way. This can be as simple as kapton tape and a high temp insulation pad. Or you can maybe find a silicone sock that can slide over the hotend. If you have the means you can also make your own.
                        3. PID tune the hotend while the fan is running at a speed similar to what it would see during an actual print, That way the system can adjust for the heat loss and maintain a more stable temperature.

                        Z-Bot CoreXY Build | Thingiverse Profile

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                        • justinds89undefined
                          justinds89 @Phaedrux
                          last edited by

                          @phaedrux

                          I printed a new shroud that I believe will direct the airflow downwards more away from the cooling block.
                          I added a silicone cover to the block.
                          I have not tuned the hotend yet.

                          I plan on testing this fix out and see if the temp holds steady. I am fairly certain it will now.

                          I can't test this until Sunday evening though unfortunately.

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                          • justinds89undefined
                            justinds89
                            last edited by

                            How can I set the Z-Offset? It is too close to the bed and I want to lower it some. I am using G31 Z2.0 in the Config.g, but it has absolutely no affect on the height regardless what I set this too.

                            I do not have a probe, but figured I could just use my Z Axis endstop.

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                            • Phaedruxundefined
                              Phaedrux Moderator
                              last edited by

                              To use just a simple endstop you'll have to comment out or remove this from your config.g

                              ; Z-Probe
                              M558 P0 H-5 F120 T4800                                             ; Disable Z probe but set dive height, probe speed and travel speed
                              M557 X25:140 Y25:130 S20                                           ; Define mesh grid
                              G31 Z0.26
                              

                              Then you'll have to make some changes to your homeall and homez. If you post those we can let you know what needs to be changed.

                              But basically if you're using a g30 command to find z0 right now you'll have to remove that and use a G1 S1 Z move similar to how the X and Y end stops are found.

                              Z-Bot CoreXY Build | Thingiverse Profile

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                              • justinds89undefined
                                justinds89 @Phaedrux
                                last edited by

                                @phaedrux

                                Ah makes sense! I think I understand now and was going about this completely wrong. Here is my homeall and home z.

                                ; homeall.g
                                ; called to home all axes
                                ;
                                ; generated by RepRapFirmware Configuration Tool on Mon Jul 30 2018 18:48:50 GMT-0500 (Central Daylight Time)
                                G91 ; relative mode
                                G1 S1 Z-250 F300 ; move Z towards the switch until it triggers
                                G1 Z5 F100 S2 ; move Z back 5mm
                                G1 S1 Z-10 F100 ; move Z slowly towards the switch until it triggers
                                G1 S1 X235 Y155 F1800 ; move quickly to X and Y axis endstops and stop there (first pass)
                                G1 X-5 Y-5 F4800 ; go back a few mm
                                G1 S1 X235 Y155 F360 ; move slowly to X and Y axis endstops once more (second pass)
                                G90 ; absolute positioning

                                ; homez.g
                                ; called to home the Z axis
                                ;
                                ; generated by RepRapFirmware Configuration Tool on Mon Jul 30 2018 18:48:50 GMT-0500 (Central Daylight Time)
                                G91 ; relative positioning
                                G1 S1 Z-250 F300 ; move Z towards the switch until it triggers
                                G1 Z5 F100 S2 ; move Z back 5mm
                                G1 S1 Z-10 F100 ; move Z slowly towards the switch until it triggers
                                G90 ; absolute positioning

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                                • Phaedruxundefined
                                  Phaedrux Moderator
                                  last edited by

                                  That looks fine for homing Z with an endstop I think. When the end stop triggers how far from the bed is the nozzle? Your homing files would assume that it is at 0. You can either adjust your endstop trigger physically or use an offset in the slicer or you could add a G92 Zn command to the homing files where n is the distance from the bed.

                                  Z-Bot CoreXY Build | Thingiverse Profile

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                                  • justinds89undefined
                                    justinds89
                                    last edited by

                                    I couldn't find a way to set z offset in Cura.

                                    The nozzle barely touched, but it is now a hair under .1mm gap.

                                    I would prefer to be able to add in a bit of extra distance in the home config when needed for fine adjustment.

                                    Thanks for the help.

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                                    • Phaedruxundefined
                                      Phaedrux Moderator
                                      last edited by

                                      It's available in Cura but I think it may be hidden by default. You'd have to do a search in the settings widget.

                                      You can also use baby stepping on the DWC or panel due for fine adjustments.

                                      Z-Bot CoreXY Build | Thingiverse Profile

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                                      • dc42undefined
                                        dc42 administrators
                                        last edited by

                                        I suggest you read https://duet3d.dozuki.com/Wiki/ConfiguringRepRapFirmwareCartesianPrinter#Section_Homing_Z_using_a_Z_min_endstop_switch.

                                        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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                                        • justinds89undefined
                                          justinds89
                                          last edited by

                                          Appreciate the help guys. I will checkout that link.

                                          justinds89undefined 1 Reply Last reply Reply Quote 0
                                          • justinds89undefined
                                            justinds89 @justinds89
                                            last edited by justinds89

                                            So just to confirm.

                                            If I use the G92 Zn command with my current configuration I need to use a negative number (G92 Z-0.2) to move the bed down 0.2mm correct?

                                            Homing Z is 0 and when I lower the bed the numbers are positive. so basically Z lowered is 140mm.

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