Tool Change - Would this be possible



  • I am going to convert one of my machines to a tool change type. In order to save wiring and have almost no limits to the number of tools I would like to disconnect the non used tools electrically. However I may then need to connect them back up on the tool rack to maintain a standby temp and any fans going etc. I am thinking of using pogo pins to do this but what will happen as the temp signal momentarily disconnects? Will the DUET error out or can I set some sort of ignore function during the toolchange process? The time taken to toolchange should only be a number of seconds so if I turn off the heater for safety the temp drop will only be a few degrees during the change. Then after the change I can again look at the temperature to control the heater?

    Also, is there any function to detect if a tool is present? Thinking here almost like a microswitch in the tool rack just to check the tool have actually disconnected correctly. If not then you would want to either try again (perhaps 3 times or something) and then pause as the tool may have been dropped or jammed. I guess this could be some sort of macro but not sure

    cheers



  • @ctrdevelopments said in Tool Change - Would this be possible:

    I am going to convert one of my machines to a tool change type. In order to save wiring and have almost no limits to the number of tools I would like to disconnect the non used tools electrically. However I may then need to connect them back up on the tool rack to maintain a standby temp and any fans going etc. I am thinking of using pogo pins to do this but what will happen as the temp signal momentarily disconnects? Will the DUET error out or can I set some sort of ignore function during the toolchange process? The time taken to toolchange should only be a number of seconds so if I turn off the heater for safety the temp drop will only be a few degrees during the change. Then after the change I can again look at the temperature to control the heater?

    I don't know if it is absolutely necessary... if it is, then the Duet/RepRap, toolchange runs pre and post scripts. ttpre0.g for example, would run before tool 0 is changed. It should be possible to set the desired temp to zero, perform the tool change, and set it back to whatever target.


  • administrators

    @ctrdevelopments using pogo pins for tool changers should be fine. I agree with @Danal if you turn off the heater for the tool change, then turn it back on again. Don't wait for temperatures to stabilise until the end of the swap when you have dropped off a tool and picked up another one, and only wait for temps to stabilise on the tool you are about to use.

    You can use spare input pins to detect tool presence and check them with either M577 or M582. it might also work using the endstop check option on G1: S2. So your Tpost for a tool will run thorough the placing sequence with the last move of that checking for the endstop to be triggered (then it knows it is in place). At that point it moves to the Tpre for the next tool which has the last move check that the endstop is released (indicating a successful pickup) before it alows the sequence to continue.

    You can simulate this before you have built the whole tool changer by using and endstop and the appropriate macros to trigger movements.



  • Both, thanks for the replies/suggestions. IT sounds like the concept has legs at least. Now all I have to do is find the time to actually do it, but I have started sourcing parts so hopefully not too long!

    To do this I would need to swap the heater inputs for each tool each time it is picked up/dropped off. Is this 'allowed' in a macro to redfine it like that? ie

    While printing the heater is on port 1, then it gets dropped into the too rack and now the heater is connected to port 2.

    I would like to maintain some temp for the tools in the rack to speed up the print time



  • @ctrdevelopments said in Tool Change - Would this be possible:

    Both, thanks for the replies/suggestions. IT sounds like the concept has legs at least. Now all I have to do is find the time to actually do it, but I have started sourcing parts so hopefully not too long!

    To do this I would need to swap the heater inputs for each tool each time it is picked up/dropped off. Is this 'allowed' in a macro to redfine it like that? ie

    Yes. There's nothing particularly magic about "config.g". AFAIK, any configuration command can be issued at any time. Also, both DWC and PanelDue are pretty good about dynamically re-defining things based on status.

    You MIGHT need to reload the web interface... and/or it may need a few tiny tweaks. I can't speak for Chris, but he has been VERY responsive to "special request" tweaks in the past.

    Short answer: The system will do it, if us humans can keep it all straight!! 🙂


  • administrators

    @ctrdevelopments said in Tool Change - Would this be possible:

    To do this I would need to swap the heater inputs for each tool each time it is picked up/dropped off. Is this 'allowed' in a macro to redfine it like that? ie
    While printing the heater is on port 1, then it gets dropped into the too rack and now the heater is connected to port 2.

    Definitely test this (you can do so without having the tool changing bit sorted). Write some test tool cahnge macros that turn the hotend on and off as appropirate, witf or endstops ans appropriate and then try it. You can manually plug the heater and temp sensors between ports (being sure the heaters are turned off when you do this!)


  • administrators

    This will be easier to do when the firmware supports a mapping from logical heater channels to physical heater outputs. This is on my list to add because the next generation Duet will need it.



  • Further to swapping the motor on toolchange I am finding that the long run of filament is causes the odd skip, so was thinking of making some sort of hybrid bowden and direct drive system. However, if I want to have lots of tools I will once again need to switch on and off the bowden drive part of the system, otherwise I am tool limited. Does anyone know of a board, effectively of transistors I imagine, where I could send a binary signal from the Duet, which would then connect only a single set (of 4) outputs to the single input (set of 4 for the stepper drive signal)? I would prefer the bowden to also retract so I dont want to just have it push, I would like it to pull back also


  • administrators

    @ctrdevelopments you would need to find a board to multiplex the step/dir (and maybe enable/) signals from one of the external driver outputs to multiple stepper drivers. I think Prusa might have something like that on his multi material adding but not sure.


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