I may need a new heatbed, as mine is so badly warped in the center, that I can print well in the center OR at the edges, but never the same (using a steel ruler, there's a noticable 0.3-0.5 mm dip in the center.. and that's with a 2mm glass plate and another 2mm build plate on top of that). While replacing the bed, has anyone changed to a 3 point leveling system and could point me to some instructions/part lists? I noticed i.e. the MK3 heating beds have a center hole already for 3 point leveling. https://reprap.org/forum/read.php?292,875957,875957#msg-875957 Mon, 10 Aug 2026 19:00:00 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?292,875957,876001#msg-876001 https://reprap.org/forum/read.php?292,875957,876001#msg-876001
I also have a 1mm aluminium sheet between the PCB and the glass to spread the heat but it does slow the heat up process. I don't think it affects flatness because it is more flexible than the glass and probably the PCB.

There is no gap under a straight edge on my bed. The PCB does curve away from it during warmup and then becomes more flat again giving a wave in the temperature curve but I do warm it to 148C with a 17V PSU for first layer ABS!

[attachment 116391 IMG_0001.JPG]

I have wondered about adding a fifth pillar in the center to stop the PCB bowing downwards but it would be difficult to adjust its height and would get hotter than the ones in the corner.

The only time my Z calibration changes is with a big change in room temperature, which causes the lead screws to expand a bit I think. I have the machine in an unheated internal garage, so it can get quite cold in the winter.]]> nophead Mendel90 Tue, 11 Aug 2020 06:04:57 -0400 https://reprap.org/forum/read.php?292,875957,875991#msg-875991 https://reprap.org/forum/read.php?292,875957,875991#msg-875991 I checked both with the bed cold and at 60°, same bend in the center.
With the clips removed, the bend is even more pronounced.
Worst part is, it loses leveling over night. Last night, I printed a case and it was beautiful, perfect skirt and first layer, all layers super smooth. Printed the same case with a small adjustment to a hole position this morning, skirt is squished to hell, nozzle is suddenly too close.]]> Arakon Mendel90 Mon, 10 Aug 2020 17:34:56 -0400 https://reprap.org/forum/read.php?292,875957,875988#msg-875988 https://reprap.org/forum/read.php?292,875957,875988#msg-875988
If you remove the bulldogs clips is is still bent?

I have never known glass to be permanently bent, although it can be bent slightly with enough force, it always springs flat. My last sheet was probably 5 years old but I recently broke it and replaced it. It was still flat before it broke.

Are you measuring it when cold or hot? Hot sheets can curve when one side is hotter than the other.]]> nophead Mendel90 Mon, 10 Aug 2020 16:50:42 -0400 https://reprap.org/forum/read.php?292,875957,875967#msg-875967 https://reprap.org/forum/read.php?292,875957,875967#msg-875967 Arakon Mendel90 Sun, 09 Aug 2020 18:33:38 -0400 https://reprap.org/forum/read.php?292,875957,875965#msg-875965 https://reprap.org/forum/read.php?292,875957,875965#msg-875965 nophead Mendel90 Sun, 09 Aug 2020 18:28:11 -0400 https://reprap.org/forum/read.php?292,875957,875957#msg-875957 https://reprap.org/forum/read.php?292,875957,875957#msg-875957 While replacing the bed, has anyone changed to a 3 point leveling system and could point me to some instructions/part lists? I noticed i.e. the MK3 heating beds have a center hole already for 3 point leveling.]]> Arakon Mendel90 Sun, 09 Aug 2020 13:21:29 -0400