Aluminium Bed with Magnets

I decided to upgrade the PCB heated bed from the BLV Cube with some nice strong Aluminium plate with magnets and bough this model on AliExpress.

star.aliexpress.com/share/share.htm

The part arrived well packed and no damages. I quickly checked that the plate was flat and could not find any problem with it.

The installation is really simple, and was without anz problem. For the heater I used a 400 W 24V Keenovo silicon heater.

At the beginning, the bed meshing was really flat and there was no problem. After a couple of month, I started to get problem to get the bed leveled. I checked the surface and it is no longer flat, like not flat. There is a couple of “bumps” appearing and these buts are around 0.2 to 0.3 mm, so definitely significant for the printing.

After looking into it a bit, it looks like there is an issue with thermo expension and the slots made for the magnets. It looks like the pocket made for the magnets is creating difference in stress in the material and the plate is bending !

On top of that, I have found that the fact the plate is mounted on the frame with screws and fairly strong springs, the plate is changing shape with temperature around this fixing points.

I really like the concept of the magnet bed, but I think it needs some rethinking. The bed should be “floating” and not firmly mounted to avoid expansion problems. Also the plate should be in one piece without any changes in thickness to avoid thermal deformation.

A new lesson learned for the Far-Out Cube Project !

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