Duet 3 6HC - Homing Dual Z
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I've read, I've tested, now I'm learning to ask for help, Please.
I built a 1 Meter Delta that's running an Duet 2 Ethernet very well.
Now have built a 500x500x500mm Cartesian.
Duet 3 6HC / RRF ver 3.1.1
Single X & Y Belt Drive / Hall Effect endstops
Dual Z Lead Screw Drive / Dual Hall Effect endstops at the top
Z axis (and U) together moving great
Initial Z Homes without splitting the pair and using just the Z endstop worked fine.
I can not seem to achieve Z & U (split) homing movement using the attached files.
Z moves, U just stares at me....
Thanks
Biff -
@biff-hansen you have used 3 two times on M584, this doesnt work.
You don't need a seperate u for two steppers for z in rrf3, please see https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors
and especially https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors#Section_In_RepRapFirmware_Num_3
M906 two values for z is also not correct. It is axis based, one value per axis (extruders are multivalue, they count as separate axes and can have multiple values). https://duet3d.dozuki.com/Wiki/Gcode#Section_M906_Set_motor_currents last sentence.
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@JoergS5
Ok, great progress, I'm guessing I morphed a some 2.x and 3.x ideas.
Z is homing and both motors stop according to they're respective MAX endstops, thanks for the quick response !
Since we're not separating Z & U, Any ideas on how I deal with small differences in the triggering of Z & U to correct slight mounting errors?I'd added the U current setting in the middle of my testing though it's remove now, per the post you sent me to.
"Example: If you have two motors on your Z axis, physically connected to Z and E0 stepper drivers, configured with M584 Z2:3, set M906 Z200, not M906 Z200:200"
Tkx
Biff -
@biff-hansen said in Duet 3 6HC - Homing Dual Z:
Since we're not separating Z & U, Any ideas on how I deal with small differences in the triggering of Z & U to correct slight mounting errors?
Use a probe instead and level the bed to the gantry.\ as described in @JoergS5 's link.
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@biff-hansen said in Duet 3 6HC - Homing Dual Z:
Since we're not separating Z & U, Any ideas on how I deal with small differences in the triggering of Z & U
Nice that you make progress!
You will have different positions between the two Z steppers with every power on anyway, because at startup steppers differ up to 2 full steps in both directions from the position when shut down. So a calibration is necessary at startup. An alternative is to use only one stepper for Z and connect the 2 spindles by a belt, if it possible for the given construction. You can find discussions here in the forum about this. If this reason why you use 2 steppers is heavy weight of the bed, you could use a gear between stepper and belt. If you use e.g. a worm based gear, it has the added benefit that the bed doesn't move down when powered off.
Not a thread of this forum, but this thread as example: https://reprap.org/forum/read.php?397,594348 -
@JoergS5
Thanks, but I want to square up this Z axis in the same manner that I do with the Dual Y carriage drive on my 1x1.5M Gantry CNC.
This one will not be relegated to only 3D printing.
I may have to go back to pursuing the split axis path.
Thx Biff -
@biff-hansen no problem, just be aware that the positions will be different at startup. If you have such a big CNC, you can route stable (and precise!) 3D printer parts easily, that's nice.
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@JoergS5
Thanks Joerg, My large CNC creeps a little while shut down, so its always
zero out homing before anything. Once I get this new one further along , I'll share some pictures. If all goes well, it will be a purpose built 3 function device (Hot End/Spindle/CO2). I've been very pleased with the 6HC, quite a step up from my Duet 2 Ethernet, which runs fantastic on the delta.
Biff -
@biff-hansen said in Duet 3 6HC - Homing Dual Z:
Since we're not separating Z & U, Any ideas on how I deal with small differences in the triggering of Z & U to correct slight mounting errors?
The following might work (not tested):
- Home both motors
- Use M584 to map Z to just one motor
- Command a short Z move to square up the motors
- Use M584 to map Z back to both motors
- If M584 results in the Z axis being flagged as not homed, use G92 Zxxx to tell RRF where the Z axis is
