Warped bed, getting worse

[Legion 2.3]

Hello printers

I did some larger prints a few days ago ( size of about 200 x 100 mm).
The prints were quite hard to remove from the bed, even after it cooled down.
It seems like the large print is causing the warping as it shrinks while cooling down.

Now, the heated bed seems to be warped a bit. It was warped a little bit from the beginning, but it looks like it´s getting worse.

When i home the extruder (XYZ), the nozzle already pushes the bed down a bit, but when i print in the middle of the bed, it´s just barely low enough to extrude a well-sticking 1st layer. (I didn´t even print 1 kg of PLA )
Is this a common problem of the 3.0 aluminum-bed?

I heard of some people who use glass as a printing surface, but i have some questions before i start to mod my printer:

- Where are the best sources for glass beds? Can i buy it somewhere with custom dimensions (covering the whole bed of the Felix)?
- How do I get the heat from the heated bed up to the glass? With a warped bed, the glass only touches the bed at the corners, so there´s just a very small amount of heat transfered. Is it recommended to use some kind of thermal grease between the glass and the bed?
- Do i need special glass, because of the high printing temperatures?
- Should I use kapton tape on top of the glass?

What are your experiences?

[killejano]

It's a bummer that the new bed desing gets warped too.

I modded my bad ages ago for a nine point levelling and I can get it really good, but I still like to use glass because I can use different print platforms.

I use 2mm glass from a cheap photoframe and alligator clips at four points. No need to use special glass (I never go above 60 degrees anyways) or heat paste. Just take some care when pulling parts from it.

As a platform I've given up on kapton and started to use avery clear stickes sheets for PLA (more about it somewhere in the forum) and for ABS I use pritt power on the glass. 60 degrees for PLA and 45 to 60 degrees for ABS depending on how big the print is and how much it wants to curl. Printing a small part at 60 degrees on the pritt glue is hellish to get of the bed.

You might want to try bendin your bed a bit if there's a big gap between the bed and the glass.

[Legion 2.3]

I use 2mm glass from a cheap photoframe and alligator clips at four points. No need to use special glass (I never go above 60 degrees anyways) or heat paste. Just take some care when pulling parts from it.

But how should the heat transfer from the alu-bed to the glass without heat paste? The glass can only touch the corners of the heated bed and i don´t dare to bend my bed, I don´t want to ruin it entirely!

Could you share some pictures of your 9-point leveling? I´m really curious how you made it.

[killejano]

I'll haveto wait for my current print to finnish before taking pics, but it's a heavy mod involving machined parts.
I also incriesed my z-travel to 255mm. My buid area now is 255x255x200

[killejano]

Here's the pics. Bed is machined and the heating resistors are glued to the bottom