Reassigning all drivers to a single axis

deckingman

@tomlj That's an odd one. Perhaps there is something embedded deep in the firmware which means that at least 2 axes have to be defined? Dunno- just a guess. But how about creating another axis like this....

M584 X0.0 Y0.1 Z0.2 U0.0:0.1:0.2:0.3:0.4:0.5 P4

This will mean that any G1 X Y or Z move will work as normal but a a G1 U move should run all 6 motors. The "P4" is necessary to make the U axis visible and to be able to control it.

Give that a try and let us know how it goes.

tomlj

@deckingman Thank you for the suggestion. If I add the line as suggested then the U axis doesnt even show up on DWC, and sending a G1 U** move doesnt work. However, if I remove any one of the drives from the list for the U axis(i.e 0.0) then it does show up, and runs the assigned five motors as before. The X,Y,Z moves work as normal as you said, do you think its fair to assume this is a firmware flaw of some sort? Thanks again.

dc42

The maximum number of drivers per axis is currently 5. You will get an error message if you try to assign size drivers to one axis. To see errors from commands in config.g, run M98 P"config.g".

I can increase it to 6 on Duet 3 if you like.

tomlj

@dc42 Though I'm sure its low on any of your to-do lists, it would be greatly appreciated if you could increase the max to 6 in a future update!

Phaedrux

May I ask why you need all 6 drivers on a single axis?

tomlj

@Phaedrux this is part of a grant-funded feasibility study for a new technology that is being developed. It requires 6 Nema 23 motors (about which I believe you assisted with my other question on power supply sizing) to run synchronously on a global radial hub with stall detection and reasonably high current per driver. The Duet 3 is capable of this and is really good value compared to alternatives, and I have been an avid proponent of the Duet series for a number of years in most applications that require stepper control. I would rather have all drivers on one axis to avoid a situation where, most likely by accident, motors are working against others that are in a locked state, which could damage the mechanism.

Phaedrux

Interesting. I hope you'll be able to share more specifics when it's up and running.

tomlj

@Phaedrux unfortunately there is a media embargo on the specifics of the project currently, but we will undoubtedly share more news when permitted!

deckingman

@tomlj Another possibility that might work, depending on your requirements, would be to create a tool with 6 extruders and use an extruder move to drive them. Something like this

M563 P0 S"6 Drives" D0:1:2:3:4:5 H1 ;

Not sure if you'd be forced to assign a heater as well- maybe not. But in any case, use M302 to allow cold extrude.

Then you'd need to set the mixing ratio e.g.
M567 P0 E1.00:1.00:1.00:1.00:1.00:1.00 ; set mixing ratio to 100% for every extruder

Then a G1 Enn Fnn should drive all 6 motors concurrently. I know this is possible because I happen to have a machine with 6 extruders feeding a 6 input mixing hot end.

dc42

@tomlj said in Reassigning all drivers to a single axis:

@dc42 Though I'm sure its low on any of your to-do lists, it would be greatly appreciated if you could increase the max to 6 in a future update!

It's a one-character change so I've already done it.