DUET3 any pin to detect poweroff and aid Zbraking?
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@engikeneer said in DUET3 any pin to detect poweroff and aid Zbraking?:
Just send G29 S1 after you have homed to Z max to load the heightmap
As long as the Z0 point is the same when homing with Z max and homing with the probe, this will work just fine.
The best way to ensure this is to have a macro that homes z using the probe and then moves to Z max and sets the actual Z axis length so that when the Z max endstop is used the position is correct.
Example
; 0:/macros/Bed Leveling/0_Set Zmax height.g ; Automates measuring the Zmax height for optical endstop at ~300mm ; M291 P"This will set Z0 and calibrate Zmax height" R"Proceed?" S3 M291 P"Homing all axis" T5 G28 ; Home all G90 ; Absolute positioning M98 P"0:/macros/0_Center Nozzle.g" ; Move nozzle to bed center M291 P"Adjust nozzle height until it's touching bed" Z1 S3 G92 Z0 ; set Z0 M291 P"Bed will now drop to Z300" S3 G1 Z300 ; Move bed down 300mm G1 S3 Z300 F200 M500 ; save m208 value for z axis to config override M291 P"Adjust optical endstop flag until light just turns off" R"Set Zmax=300mm" S3 M291 P"ZMax homing will now be tested, starting with homing Zmin" S3 M291 P"Homing to Zmin" T5 G28 Z M291 P"Ready to test Zmax homing?" R"Proceed?" S3 M291 P"Homing to Zmax" T5 M98 P"0:/macros/2_HomeZMax.g" ; Test Zmax homing M291 P"ZMax homing test complete. Printer will now home all." R"Proceed?" S3 G28 ; Home all M291 "ZMax calibration complete." S3 -
@jayt said in DUET3 any pin to detect poweroff and aid Zbraking?:
What I understood from heightmap is its for mesh bed compensation. Even if I reload map using G29, how will it get applied when I resume print after power failure ? Can you elaborate on this for me please?
I never had a power failure, but fom what I know, the last position is stored on SD.
After homing to Z-max and applying G29 S1 but before hitting the resurrect button, you can direct the nozzle to that position and see if it's reasonable. With a little luck you are somewhere in the infill so it's safe to do minor adjustments to the position if needed.Worst case in a power failure scenario is the bed temp dropping to a point where it's almost certain you'll kick off the part when you continue printing.
If you see power grid failures often where you live, it's probably safer to use a backup battery. (old e-bike or RC hobby LiPo batteries)A more advanced
solution would be an automatically compensated counterweight : You'd install two empty buckets as counterweights for the empty bed and during print you fill them with water to compensate for the filament weight. A peristaltic pump parallel to the extruder could do this. Change mixing ratio for different filament density.
...crazy idea, I know
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Thank you for all the replies. I used M569.7 with one of the out signal, so on power off, the bed fall is now quite less. So I donot wish to include counter balance, but instead check if G29 can help.
@phaedrux , @engikeneer :
a) I need a little help to understand what happens when I run G29 S1 on power on, when config is read. From my understanding, this will load the height map, but to perform mesh bed compensation. It does not apply correction to ball screw like we do in bed levelling in one shot right? it will be a correction that will apply at each layer right until taper height?b) Suppose first few layers we applied mesh bed compensation. Now after say Xmm height, power goes off.
Now if I use Zmax homing and resume, will it not resume at proper height? Will there be chances of nozzle hitting the print due to compensation applied?c) @dc42: Is there a way, the way we save heightmap , we can use this to run Auto-level on power up by updating few things in the firmware? I am ready to try if there is a way?
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@jayt G29 S1 should not be used in config.g. The heightmap should only be loaded after your Z axis has been homed. In the case of power loss resume, the correct place to load it would be in the resurrect-prologue.g file after the Z axis has been rehomed.
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@phaedrux : ok understood.
Can you clarify one more question, IF we define taper height, and after Zmax home-> resume-> it will again apply correction for defined taper height right?
i.e. if taper height is 10, then on resume if Zprinted is >10mm, it will again apply correction for 10mm ?
(I know this is silly question, but I am new to this topic. ) -
@jayt said in DUET3 any pin to detect poweroff and aid Zbraking?:
it will again apply correction for defined taper height right?
i.e. if taper height is 10, then on resume if Zprinted is >10mm, it will again apply correction for 10mm ?That sounds correct to me.
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@jayt no, it will only apply correction from z=0 to z=10 (in decreasing amounts). So if you resume a print at z =50, no correction will occur
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@engikeneer @Phaedrux : Both of yours answers are contradictory
Can you check if you have these settings in place?@dc42 : Any way to apply last learned deviation corrections, after Zmax homing , on power up , by changing RRF? I tried to check few files, in Zleadscrewkinematics.cpp, can we use function: "Write ResumeSetting()" to call function that applies last learned corrections (if saved) ? Do you suggest to do so?
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@jayt In the original thread you linked, there are photos we posted of an early prototype which used a bank of relays to assist in z-braking. We gave up on that idea and worked with LDO to create a high torque stepper with integrated 24v brake.
We are having great success with these steppers and the new motor brake functionality in the 3.4 betas. We'll be selling these on website as soon as it launches, but please reach out now if you think it could help you as we have them in stock. FYI - the specs are
- class H (high temp)
- 1.8° step angle
- 8.5Kg-cm Holding Torque
- 2.0 amp
- 24v 5w electromechanical brake
- 50ms on/off delay
- 6Kg-cm Holding Torque
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@jayt said in DUET3 any pin to detect poweroff and aid Zbraking?:
@engikeneer @Phaedrux : Both of yours answers are contradictory
Can you check if you have these settings in place?I misread your question. @engikeneer is correct.
