Warped heatbed problem

[bondebond]

I just received a RepRap PCB MK2a heatbed from geeetech. When laying it on a flat table and other surfaces, I noticed that two opposite corners do not lay flat against the table. Upon further inspection, the center is raised about 1mm to 1.5mm when viewed through the hole for the thermistor. I have tried to bend it back the opposite direction with modest weights but that seems to have no effect. Is there any correcting this or does it need replacing?

[Lemon]

Dear friend,
Thank you for your post.
The heatbed may have some uneven.
When you printing, you can't print directly on the heatbed, you need add a piece of glass above the heatbed.
Best regards.

[bondebond]

Yes, I realize that. Even with the glass clamped on, there is still distortion. The glass is 3mm thick and is warped when clamped to the heatbed but not as bad. When .1mm difference in bed height matters for getting good prints, this is still outside of tolerance.

[Lemon]

Dear friend,
The hotbed is fixed with spring screws, you can adjust the level of hotbed by adjusting the screw.
Best regards.

[bondebond]

The board is warped towards the center. You cannot fix it with the spring screws. The hole in the middle is for the thermistor. It is like a concave bowl. While the opposite corners are warped a little, the problem is having a center that is warped. It is strong enough that it makes the glass warped. There is no way to correct it unless I get 5mm glass and that is just not available for me and that would take significantly longer to heat up.

[neilcoggins]

Hi,
I've got the same problem (and a bunch of others that are unrelated) - how did you fix the warped headbed in the end?

[bondebond]

I used a much thicker piece of glass and lots of clips to pull the heat bed to it. I also changed out the laser cut wooden carriage underneath with a solid plywood that was almost twice as thick. This has resulted in a stable platform and I now get consistent results. It has basically doubled the weight of the build platform but I bought strong stepper motors in the beginning for a reason.

[Ruffturn]

How thick of a piece of glass did you use and where did you obtain it? I have an Acrylic Pro C dual extruder and the bed of mine with the glass is considerably higher in the center than the corners and edges. I was adjusting my print nozzle to bed distance at the edges and found that adjusting it to the right dimension in the middle worked. Unfortunately, the outer edges are low and I'm still having adhesion problems there.

Thanks,

Charlie

[jroberts235]

I believe the DELTA_RADIUS attribute is what you need to adjust.
It's for the condition where the outside point are level but the center is not.