Do I have a bad Rambo board?
I have a new MK2S and it prints great! But I have noticed when I first turn it on with no inputs or adjustments I can hear very quiet whispery whine. If I let it sit there for a bit I notice both Z axis steppers get warm. So I started checking regularly and they are always warm if the printer is on. After a print and I don't retrieve it for a while (sleeping) and it all cools down, the Z steppers are still warm. X and Y steppers are always cool unless mid-print.
This morning I turned on the printer and the whispery whine was quite loud. Surprisingly loud, coming from Rambo. I gently touched the Rambo case to see if I could feel any vibrations and the door "settled" (micro-creak as it released some tension) and the sound stopped (back to quite whispery whine). Z steppers are still warm.
So I am wonder if the Rambo has a bad component, like switching regulator, that is allowing current to the Z steppers when they are supposed to be off. Or is this by design to hold up the X carriage from falling? I don't think that would be necessary.
Thanks for any help.
-- Jon
Re: Do I have a bad Rambo board?
Z Steppers are always on.
What you are experiencing is quite normal.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Do I have a bad Rambo board?
Thanks for response. So I needn't worry.
Why are they always on? Is this to hold tension to keep X level?
-- Jon
Re: Do I have a bad Rambo board?
Since the steppers don't know where they are in real space, they only count steps, you need some way of know where "home" is.
For X and Y, we have home switches, so it can always "home" before a print, and know where it is, so the PRUSA turns off the X and Y steppers. You can move those by hand, and it will re-home before a print.
There is no "Z" home function. The "calibrate Z" crashes the Z to to the top, and calls that zero. It then just counts from the last "calibrate Z" position. To prevent you from "bumping" the Z and having that calibration be incorrect, the PRUSA keeps Z energized, so it is harder to move - less likely to lose count.
A bad Z "zero" can be hazardous to the printer. if the head is lower than the software thinks, it will crash and scratch your bed. Also, if the two Z steppers get out of sync (one get's bumped higher than the other), your whole Z will be unlevel making your prints fail (bad first layer, or worse).
So it is in your best interest to keep Z active at all times, and to occasionally do the "Z calibration".
Hope that helps.
Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…
Re: Do I have a bad Rambo board?
There is no "Z" home function. The "calibrate Z" crashes the Z to to the top, and calls that zero.
No. No. No.
"AutoHome" will home the Z at a distance of 0.15mm above the bed.
"Calibrate Z" gets you to raise the Z axis to the top Z end stops in order to ensure that both sides are level; from there it performs an "Auto Home" to set the Z axis as above.
The Z end stop is, of course, the induction probe which is used to detect the probe/bed distance.
Ideally, the Z axes should be moved to the top end-stops whenever the printer is turned on or power-cycled.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Do I have a bad Rambo board?
There is no "Z" home function. The "calibrate Z" crashes the Z to to the top, and calls that zero.
The Z end stop is, of course, the induction probe which is used to detect the probe/bed distance.
Ideally, the Z axes should be moved to the top end-stops whenever the printer is turned on or power-cycled.
Peter
Peter
THANK YOU. You are correct. The dual Z steppers are kept powered to keep their relative alignment and prevent small bumps from harming that.
The PINDA helps set Z=0.
Thanks for correcting my thinking.
Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…