Compensate for bed warp?

I have a home-built printer with a very large bed (500x500).

The problem I have is that when the bed is cool it is completely flat but when I heat it up it gets a very slight bowl shape where the center is just slightly lower than the edges.

I can still print but the first layer in the center is a bit "blobby" while the first layer closer to the edges is perfect.

I used a dial caliper to measure the effect and know how much I would need to compensate for this effect.

Currently I can get around it by rafting but what I would really like to do is tell the firmware (Repetier 0.92.5) or the slic3r to compensate for it.

Is it possible to do this?

Thanks...

RKM

Edited 1 time(s). Last edit at 12/26/2015 12:47PM by RKMore.

I wish it were possible.
As far as I'm aware all the current z probing only compensates for bed non-level, not for hills and valleys in the bed.
I would like to see this implemented where the bed defects are blended out in the first few layers.

I solved the problem mechanically. I added a 5th bed level adjuster in the center.

Makes leveling the bed a bit of a pain in the rump (I have a dial indicator that I attach to the extruder) but in the long run I think this is easier.

We are working an making bed distortion correction also work for cartesian printers. Should come the next days as version 0.92.8 together with new bed leveling implementation allowing also regression planes for better fitting without extra correction.

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