Bed is warped--concave upwards
As I'll show in the pictures, my bed is warped, concave upwards, like an overturned bowl with the high spot in the very center. The bed mesh leveling appears to be overcompensating and dropping the Z too far for any point off the center.
I've had a number of challenges with getting prints to stick--I've replaced thermistors, Prusa was very kind to send me another heater, I've rebuilt the bed so as to be perfectly square (to the mm), I've tried everything.
Here is the bed against a straight edge (result is the same from the Z frame as well as the X-bars):
And the gap of 2.5 mm at the leading edge:
I created a full-bed print with some cutouts to show the adhesion of the first layer across the entire bed. The first pass was abysmal--the Z was set for the center, and ended up plowing into the bed around the perimeters. The bed mesh leveler is trying to compensate but is actually dropping Z too far at the perimeter:
After backing off the Z slightly, here is the full-bed print:
And here is a close-up of the left side:
The bed mesh leveler is trying to compensate, but just can't make it.
I've got regular dragging of the nozzle across all of my prints that are in the center, because I've set my Z low enough to ensure it sticks off the center of the bed.
How do I go about getting another bed that isn't concave?
Re: Bed is warped--concave upwards
My first MK42 heatbed was also bent. There was about 1,5mm gap between the bed and ruler attached to oposite edge. I got replacement from PR for free. New bed is almost perfect flat.
Re: Bed is warped--concave upwards
Hi Curtis,
best way seems to contact Prusa support on the chat, and to provide the link of this thread.
I'm like Jon Snow, I know nothing.
Re: Bed is warped--concave upwards
Thanks people! I connected with Josef and it sounds like a new bed might be in order.
Re: Bed is warped--concave upwards
Same happened to me...
My MK42 bed is not flat anymore. It's in the mid about 0,5mm deeper than on the edges, but only on the x-axis direction. Y-axis does follow the distortion.
My prints are failing all over again, printing in the air, or scratching the surface.... 🙁
I think It started after I printed some ABS and heated the bed to 90°C
Re: Bed is warped--concave upwards
So is it heat that is causing the beds to warp?
Re: Bed is warped--concave upwards
It's in the mid about 0,5mm deeper than on the edges, but only on the x-axis direction.
This should be easy to fix. Put washers under central nuts. 🙂
Re: Bed is warped--concave upwards
But why isn't the PINDA probe this compensating?
Re: Bed is warped--concave upwards
It is not compensating at all or it is not compensating enough?
Try this gcode:
M109 S170
G28 W
G80
M104 S0
G1 X0 Y100 Z20 F1000
G1 X250
G1 X0
G1 X250
G1 X0
G1 X250
Either enter them one by one in Pronterface command line or save it to gcode file and run it from SD card.
It should do MBL while heated up to 170, then move few times from left to right. If MBL works well, you should see movement of Z axis during X-moves. If the bed is off-shape by 0,5mm, Z axis screws should turn by about 22 degrees.
Re: Bed is warped--concave upwards
After testing this, the Z-axis does move slightly.
Re: Bed is warped--concave upwards
How much? Full revolution of Z axis screw is 8mm of height. How much does it compensate?
Re: Bed is warped--concave upwards
About your estimated 22deg...
it's a very small movement
Re: Bed is warped--concave upwards
Allright, then it is most likely working well (in tolerance of probe triggering height), you only need to fine-tune the result using menu commands. See http://help.prusa3d.com/mk2-movement-calibration/calibration-print-is-uneven-or-more-squished-on-one-side and tune both left and right side.
Re: Bed is warped--concave upwards
I've already tried this, but the the max is just 50um, about 0,05mm.
Take a look at the pictures...
Re: Bed is warped--concave upwards
I wonder what do you use for bed cleaning. I can see in your pictures there are some places where it obviously should stick but it doesn't.
Anyway, if bed deformation is rather local, MBL won't cope with that. MBL measures at 9 points grid. If the deformation is way smaller than that grid, calculated mesh will not cover it fully or exactly. In such case you should contact PR and ask about bed replacement.
Re: Bed is warped--concave upwards
I'm using window cleaner, worked well until now.
But even with Glue stick it won't stick.
Re: Bed is warped--concave upwards
I have bad experience with window cleaners.
Re: Bed is warped--concave upwards
Hmm, I don't have IPA. Just vodka 😉
edit: which surprisingly is better working as the window cleaner... 😆
Re: Bed is warped--concave upwards
Hi,
Looks like I am having the same problem ( photo attached ) . Just sent an email to prusa team and waiting an answer. Having big issues with first layer. Wondering if you received the replacement bed and if it was ok.
Marius.
Re: Bed is warped--concave upwards
I would check if the six hex stand offs which hold the bed are too loose or to tight (one may be too short or similar or some defect hinders them to get the correct height). So undo the bed and if it is loose anyway check if it is still bend when not in place.
Carsten
My Prints: https://www.prusaprinters.org/social/15695-carsten/prints
My Employer: https://make-magazin.de