Multiple Tools using single inputs

CTRDevelopments

I am considering building in tool changing into one of my machines. I do however have a question. As I have already used up lost of the motor inputs etc and do not have enough for all the tools I may need, I thought about have the toolhead not only mechanically disconnect from the moving carriage but also electrically. This would mean I could in theory have many many tools but the thermistor readings, fan control etc, would always go to the same input on the Duet. When docked the tools could then connect to always on pins to run the fans to stop heat creep etc. My question is 'is this possible to configure on the duet' as normally you have to define the tool 0 extruder as a specific connections on the board. Will it allow me to configure tool 1 and 2 and 3.. to be the same extruder output, same temperature input, and same fan output on the Duet?

deckingman

Interesting idea. No doubt DC42 will step in soon to confirm but in the meantime, I run a mixing hot end so I have multiple tools assigned to the same drives and sharing the same heater so I'd say on that basis that it ought to be possible. The only thing that would bother me is if you want to disconnect and reconnect stepper motors - this is not good idea with the machine powered up as you could end up with a blown driver.

timcurtis67

I have been designing and planning a similar approach to adding tool changing to my printer.
My idea for the stepper motor disconnect would be to M84 that driver before the tool change and then re-enable it afterwards. If that isn't good enough to protect the driver then I have an alternate "plan" but I'm not ready to share it yet.

deckingman

@timcurtis67 said in Multiple Tools using single inputs:

I have been designing and planning a similar approach to adding tool changing to my printer.
My idea for the stepper motor disconnect would be to M84 that driver before the tool change and then re-enable it afterwards. If that isn't good enough to protect the driver then I have an alternate "plan" but I'm not ready to share it yet.

Hi Tim,

Good call. Yes you can "M84" specific motors. I've even set up a macro to do just that - M84 E0:1:2:3:4. turns off all my extruder motors but leaves the rest of the motors on idle hold, so homing status isn't affected (as it would be using just M84).

dc42

You can configure multiple tools to use the same heaters and/or extruder drives in the M563 command.

CTRDevelopments

Thanks for the info everyone. Do we think that an m84 would protect the driver as I have got concerns myself over that.

In order to define the tool would I just define it in a similar fashion to normal and let the Duet work out what its doing? I would most likely need to store offset 'tool lengths' for each tool but could that be defined separately for each tool even with the same temp sensor etc?

dc42

M84 followed by a short G4 delay command to let the motor current decay ought to be safe. Avoid connecting a motor to a stepper driver outputs when the motor has built up static charge.

Your bigger problem is likely to be making sure that the contacts are reliable enough to provide a solid connection after you turn the motor on again.

CTRDevelopments

@dc42 said in Multiple Tools using single inputs:

Your bigger problem is likely to be making sure that the contacts are reliable enough to provide a solid connection after you turn the motor on again.

I am looikng at disconnecting the drive from the tool so it is the same stepper motor that drives all the tool with the electrical connections being for temp and cooling fans etc which hopefully if they dropped out momentarily it wouldn't cause an error?

dc42

Heater/fans dropping our momentarily shouldn't cause problems for the Duet.