Questions about How Auto Bed Leveling Works

[Roxy]

ooops... I started this post before lunch... And then just finished it. I didn't see that everybody else had jumped in!

Interesting. I was under the impression that the EEPROM has a more limited number of writes/rewrites then typical memory and that it should only be used when necessary for permanent value changes, but I could be totally wrong! I don't even know if the RAMPS has another type of memory.

It is limited in the number of erase cycles that it can do... But it is guaranteed to be up around 10,000 or so. Probably way more. And the whole intent of doing this is so you don't have to do the probing at the start of each print. So until your bed gets too far out of kilter, you would not re-probe and save the new settings. You would just keep using the previous bed level correction matrix.

So could one bake the G28 and G29 into the start up GCode after the bed has reached its desired temp?

Yes. That is what is done. This is what my Slicer Start GCode is:

G1 Z15 F2000 ; lift nozzle
G28
G29 v4 n3; Do bed leveling probe
G1 Z15 F2000 ; lift nozzle

I'm guessing this is a non-issue but does the probe switch ever show signs of melting with the heat from the bed?

No... The plastic roller I have on my super cheap micro-switch is just fine. I suspect the plastic doesn't melt until a much higher temperature. But it is only touching for an instant. And the bed is at a much lower temperature than the nozzle. I do get a little bit of a coating of hair spray on it however!