Hello!
I tried the A1 mini. It is a fantastic machine. I am a software engineer, not a mechanical engineer, so I am open to learning if I made a mistake.
I read in documentation that Power Loss Recovery can only recover Home position of X and Y axis, but Z axis cannot be homed and must use last known memory points to recover a print.
Rehoming of the X and Y axes is usually safe because these axes travel to locations that are clear of the printed object.
Z rehoming is impossible as the toolhead cannot probe the bed. Instead, the machine trusts the previously stored Z value and positions the Toolhead based on that reference. This approach demands high mechanical accuracy and stable Z motion.
I personally notice good functions with X and Y rehome on power loss, but sometimes have a toolhead-part crash from Z axis not being perfect, and the print is then lost.
Instead is it possible to home Z axis by moving the Z axis to the MAX height possible, and then use arithmetic to calculate the home?
Process implementation:
- Before printing, while homing, store maximum Z height on SD card in power loss recovery files
- Boot after power loss
- Can home X and Y to safe area like normal
- Can estimate home Z by moving up toward max height to calculate minimum from previous known max height
Does this make sense? Would it work?
Fantastic printers again.
Thank you
While creative, I dont think youll get better results. The top z is a bang-stop not a position switch nor a pressure sensor like the nozzle uses at the bottom, so it would differently calibrate. My experience with powerloss is a usable functional part but an aesthetic fail, the misorientation is usually under like 0.1mm. but thats a huge shelf for an aesthetic piece.
Powerloss recovery that can be aesthetically good must use much more fine sensors like lidar etc to compensate for the stepper deenergizing, losing position, then reenergizing uncalibrated, and attempting to go into the same position. Whatever the degrees between the poles are in the motor windings is your systems total possible slop, so it’s not very far but it is very real. A1 just aint got the right sensors. Maybe possible on the flagships.
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Agree with Bullocks - z height in these machines is very precisely determined using the force transducer in the toolhead - there isn’t a software solution that will get this with a “bottoming out” retouch, and is more likely to result in a bad Z and either a collision or an even bigger gap.
The best solution is a UPS.
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Please add the option to automatically resume after power loss, it must be super easy to add.
That is absolutely, positively, 100% never going to happen.
What happens when you have a large print on the PEI bed, there’s a 1-hour power outage, in that time the bed cools and the part releases, then the printer tries to resume anyhow, catches the part and mangles itself when the part moves?
Auto resume is an recipe for destroyed printers.
It’s important to always check that the print is safe and in a state where it can resume, and then monitor the first few layers after a resume to make sure it’s going OK.
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Does not harm to have the option, it can be OFF by default, let the user decide… A short power outage makes it cool off while it has power and it waits for pressing “continue”. We are in an area where power outages are less than a minute, and without this option, I cannot make it run all night.
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IMO this is the job of a UPS or power station. You’re in luck, the A1 mini sips power, the UPS does not need to be very strong, it will be very cheap.
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Get a UPS dude.
And if you can’t figure out why a feature request based on your incredibly specific use case could be bad for the wider community, don’t request features.
Thank you for your reply, yes I guess this is the best I can do.