tool offsets for new tools

Discussion in 'Tool heads & ToolChanger' started by Siril Teja, Jan 20, 2020.

  1. Siril Teja

    Siril Teja Member

    Joined:
    Jan 9, 2020
    Messages:
    9
    Likes Received:
    0
    I am designing a new tool for the toolchanger. Can someone guide me where do I have to swap the values of the tool offsets.
     
  2. mhe

    mhe Well-Known Member

    Joined:
    Sep 5, 2015
    Messages:
    279
    Likes Received:
    76
    In your config.g, look for these lines fairly at the bottom of your fille:

    Code:
    ;tool offsets
    G10 P0 X-9 Y39 Z-4.65                    ; T0
    G10 P1 X-9 Y39 Z-4.85                    ; T1
    G10 P2 X-9 Y39 Z-6.02                    ; T2
    G10 P3 X-9 Y39 Z-4.55                    ; T3
    
    Be aware that above that, there is another block where all the tool offsets get reset to zero. Leave those alone, these are just for a clean starting point, ALWAYS edit the second offset block, or your changes will be in vain. Don't ask me how I know. :p
     
    Jason Chodakowski likes this.
  3. Siril Teja

    Siril Teja Member

    Joined:
    Jan 9, 2020
    Messages:
    9
    Likes Received:
    0
    these offsets represent the x,y,z distances from the nozzle to the tool center right??

    If yes, I understood this part.

    But what about the tool station offsets. I had to extend the tool dock in my design. where do I account for this y offset? I suppose you understand what I mean.
     
  4. mhe

    mhe Well-Known Member

    Joined:
    Sep 5, 2015
    Messages:
    279
    Likes Received:
    76
    I believe they are relative to the probe switch that does the z-homing and bed probing.

    My approach always was to get the tool pickup to work, then manually jog a tool close to the bed surface (piece of paper method), taking note of the displayed Z position. Then I'll adjust the Z offset of the tool, restart the printer. That gets you in the ballpark. Second step, I verify by printing 1 layer and measuring the thickness of the test surface with calipers, fine tune Z offset and run it again. Repeat until the first layer has the exact length you have specified in your slicer.

    For X/Y, similar approach works. With T0 equipped, jog it to X/Y zero (in my case the front left corner of the bed), take note of the displayed X/Y position and then just adjust the offset by the displayed amount. Edit config.g, restart, verify.

    Once all the tools are in the ballpark, take T0 as your X/Y reference. Print the vernier scale STL provided by E3D to fine tune tools 2,3 and 4 to match T0.

    By doing it all in that order, you should always end up with aligned toolheads, irrespective of how different the particular printheads are.
     
  5. Paul Meyer

    Paul Meyer Well-Known Member

    Joined:
    Dec 18, 2019
    Messages:
    49
    Likes Received:
    8
    I just went through this.

    For the dock:
    - I made sure no tool was active (t-1)
    - I put the tool on the tool-changer and used the “coupler-lock” macro to grab it
    - I manually walk the tool back to it’s dock, doing the best I can to line up the pins.
    - I nudge it all the way until the tool connects to the back of the dock
    (The first time you do this, you may want the dock loose, and adjust/tighten down the dock. Here I’m describing the measuring step)

    I then record the coordinates, and modify tpreN.g and tfreeN.g (mostly changing the x coordinate and the final y coordinate). If you watch a working tool load/unload, you can see the several steps it takes to pick up and drop off the tool. Adjust those as needed. It’s also worth slowing down the load/unload significantly at first, so you can try it with your hand on the power switch the first few times and have time to react if it is not lining up.

    As for tool head offset (in config.g), I placed a piece of tape on the center of the bed and marked a small dot on it with a sharpie. I then manually moved the z-probe directly over that point and down until it clicked exactly on that spot. I recorded x/y/z.

    I then manually moved over and *manually* picked up the tool basically typing in the tfreeX.g commands, the coupler lock macro, and then manual moves to nudge the tool tip to that dot, lowering until I couldn’t slide a piece of paper under it directly on that dot. I recorded this x/y/z. The difference between them was my starting tool offset in config.g.

    I used the “fine tune z” method in the dozuki guides to nail down the z, and multi-material calibration to fine tune x/y, but this gave me a working starting point.

    **Important** if you use t0/t1/t2/t3 to pick up the tool above, instead of manually picking it up, reprap and DWC switch coordinate systems by applying the existing offsets from config.g to that tool. That makes the above method much more complicated (as the z-probe coordinates and the tool-tip coordinates when both are on the dot are in shifted coordinate systems). You could figure it out, but it is much simpler just to move the TC over and pick up the tool ‘manually’.
     
    mhe likes this.
  6. Nibbels

    Nibbels Well-Known Member

    Joined:
    Dec 12, 2019
    Messages:
    150
    Likes Received:
    28
    To create a link to the microscope idea:
    https://forum.e3d-online.com/threads/diy-motion-system-and-tool-changer.3441/page-2#post-34750
    I aligned my xy-coordinates this evening. And I got awesome results using a cheap usb microscope. (+-0.025mm)
    Screenshot_2.jpg
    I connected the microscope via VLC player and used full screen picture.
    First I did center the microswitch of the coupler and marked the exact position on the screen using a piece of tape.
    Then I grabbed a tool using T0/T1/.., placed it over the microscope at the tapes position and changed the G10 Px [XY...] offset gcode (sent via console) until the coordinates did fit perfectly (to the couplers microswitch buttons coordinates).

    I adjusted the Z-coordinate by driving at a edge of the heated bed. Then I lowered the nozzle until I hit the bed and did the same itereations using G10 until the coordinate was Z=0.
    So both of the nozzles are equal. I will add the compensation offset tomorrow. (Because the z homing position is not at the edge where I did the z-probing today.)
     

Share This Page