Powering on with tool attached

Discussion in 'Tool heads & ToolChanger' started by schneik, Dec 24, 2019.

  1. schneik

    schneik Member

    Joined:
    Nov 3, 2019
    Messages:
    16
    Likes Received:
    7
    I'm finishing up my build... I may have missed it but what it the best way to park a tool after powering on?
     
  2. Paul Arden

    Paul Arden Well-Known Member

    Joined:
    Aug 28, 2019
    Messages:
    99
    Likes Received:
    27
    As far as I can tell you can’t since you have to home first. Obviously you absolutely don’t want to home Z with a tool attached, however fortunately you can home Z after C. So what I end up doing is homing C while holding the tool by hand and catching it when it falls off during homing. Not idea but the only way I have found to get the tool off after a restart with the tool still on.

    Be great if someone else has a better way.
     
  3. John Meacham

    John Meacham Well-Known Member

    Joined:
    Dec 18, 2019
    Messages:
    47
    Likes Received:
    17
    It would be fantastic to put the z endstop at the other end and home Z with the plate moving downward. It would mean it is always safe to home, even mid-print or when you don't know what tool is attached. Plus it puts the bed right where you want it to prepare it for the next print or remove the previous one.

    It's really incredibly useful to be able to re-home and recover from missed steps in the middle of a build or if you have to reach in with your hand and manually move motors out of the way to repair something.

    When you have different tool heads with different z offsets that you need to calibrate anyway, you are going to choose something arbitrary as your reference, so might as well choose one that is out of the way and doesn't lead to tool crashes.
     
  4. Paul Arden

    Paul Arden Well-Known Member

    Joined:
    Aug 28, 2019
    Messages:
    99
    Likes Received:
    27
    Should be possible to find somewhere to add a z-max and home to that. However you’d still need the z-min for mesh compensation if you want to use it.
     
  5. schneik

    schneik Member

    Joined:
    Nov 3, 2019
    Messages:
    16
    Likes Received:
    7
    I should be able to make a macro that lowers z, homes x and y and then stows a tool by bypassing the z home check. Id need a macro pre tool, but that would at least let me get a reasonable power up process.
     
  6. Andy Cohen

    Andy Cohen Well-Known Member

    Joined:
    Aug 23, 2019
    Messages:
    216
    Likes Received:
    55
    I habitually manually push the carriage into the parking place when a tools attached and for some reason the steppers are disabled... e.g., an emergency stop, a power down... any other situation the tools are parked automatically.
     
  7. Paul Arden

    Paul Arden Well-Known Member

    Joined:
    Aug 28, 2019
    Messages:
    99
    Likes Received:
    27
    I like that idea rather than trying to catch it. However how do you get it to drop the tool since you can’t really manually move the C axis to get the tool to disengage?
     
  8. Jai Stanley

    Jai Stanley Well-Known Member

    Joined:
    Aug 28, 2019
    Messages:
    115
    Likes Received:
    60
    I'm in the habit now of hitting home all walking to the printer and 'catching' the tool head and manually docking it.. I normally only have to do this after I've hit reset for some reason..

    When the new Duet firmware with conditional G-Code; we will be able to modify the machine to know which tool is loaded. I'm thinking a microswitch on each dock station and one on the head. That way it knows if one is loaded, and which one is missing off the docks (therefore which one is loaded or if there's an issue).

    For now: you just need to get into habits of checking I think. Not too bad.
     
    Ntesla66 likes this.
  9. SolTroy

    SolTroy Member

    Joined:
    Mar 24, 2018
    Messages:
    2
    Likes Received:
    0
    First post, so, Hello Community ;-)

    I thought a lot about this too - best approach I've come so far would be
    • PogoPins on ToolChanger, different Resistor on every Tool which closes the loop
    • PogoPins on Dock which are also closed with the Tool resistor. Although a microswitch would be enough, with a resistor the tool can also be identified when it sits in the dock
    Prerequisites....
    • Analog Input for ToolChanger which reads the resistor value
    • Analog Input for every Dock to read the resistor value
    • Firmware feature for Tool-ID by resistor value
    With this, FW would always know which Tool is attached and also which Tool sits in which Dock. This would also open a path where you actually can configure "endless" ( I'm looking at you, Duet 3 CAN Bus ;-) ), swap-able Tools.
     
  10. Greg Holloway

    Greg Holloway Administrator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    911
    Likes Received:
    592
    While pogo pins sound like a great idea, there are two problems. Firstly there is a patent restricting their use, one could argue that this doesn't matter on a personal machine, however you may find designs get taken down. Secondly the cycle life of the pogo pins is nowhere near enough to handle the number of toolchanger required for a normal printer. The average 4 material print has somewhere around 6000-10000 tool changes, most pogo pins are rated for 100,000 cycles.

    You could mitigate the problem by only using the pins for the swapping of tools in and out of the system, but then you might aswell just use a proper quick-release connector.

    The idea of hot-swappable tools is an important one, and something that will need to be solved when people want to use carousel-style tool changers.
     
    Ntesla66 and Jai Stanley like this.
  11. Jai Stanley

    Jai Stanley Well-Known Member

    Joined:
    Aug 28, 2019
    Messages:
    115
    Likes Received:
    60
    RFID tags and readers are incredibly cheap and fairly easy to impliment these days. I've used resistor ladders on jigs and fixtures in industrial machines in the past; and wouldn't anymore for the reasons Greg highlighted above: and that's on a few swaps a shift!

    One of my next jobs is to make a common toolhead connector standard for my machine as I want to impliment an E3D TC head on a heated chamber build I started a while back. I'd like to have a selection of toolheads with various nozzle/heater/block/extruder combos and swap them between machines etc. The mixed D-Sub connectors look perfect (a 13w3 has three large format pin holes: two power and one 4mm PTFE feed tube for instance and enough pins for a print head). This doesn't solve the problem of on the fly quick release though. Harting make some nice industrial connectors. You could start the search in their catalogue perhaps?
     
  12. SolTroy

    SolTroy Member

    Joined:
    Mar 24, 2018
    Messages:
    2
    Likes Received:
    0
    Jeah, patents.... :mad:
    Didn't think of that, but I guess the community will find a solution.
    Quick thought - 4x Color SMD Sensor on a daughter board for ToolChanger & Dock, 4xBlack/R/G/B reflecting dots on Tool would result in 256 Tool possibilities. (Maybe I should patent this... :p)
    Quick-Release connector would, if I understand this correctly, require a manual step.

    Nevertheless - first step would be a FW feature to support Tool-IDs...
     
  13. Aluminati

    Aluminati Member

    Joined:
    Dec 27, 2019
    Messages:
    7
    Likes Received:
    3
    I'm really interested in what you come up with. The first time you have to take a print head apart or swap something out on any 3D printer you think "Why aren't the fans, Z probe, thermistor, and heat cartridge all one plug?" Then you add a platform with the ability to have multiple tools and it makes that much more sense.
     
  14. garethky

    garethky Well-Known Member

    Joined:
    Oct 8, 2019
    Messages:
    49
    Likes Received:
    28
    This is something that I kinda want to fix. This comes up pretty much whenever you hit the E-Stop button.

    I could see how tool geometry could prevent accurately homing X and Y on boot up. So putting the tool back automatically and safely is probably going to require something like Power Panic on the Prusa machines where we write the XYZC coordinates to the EPROM and then use those to put the tool back.

    Yay open source: https://duet3d.dozuki.com/Wiki/Setting_up_to_resume_a_print_after_a_power_failure
     
    #14 garethky, Jan 9, 2020
    Last edited: Jan 9, 2020

Share This Page