Leveling w/ Heated Bed On

Hello again!

I’m trying to level my SM2 A350 bed. It seems that when using the touchscreen, if I exit the screen to control the bed temp, it sets the temp back to 0. As a result, if I heat the bed to 70 and then start the automatic leveling through the touchscreen, the bed is cooling through the entire process.

Figured I’d connect with Luban and set the bed temp via M140, then run the automatic leveling routine. But, for the life of me, I can’t figure out how to do that. I tried G29, but very nearly crashed the extruder into the bed.

How do you run the automatic leveling routine with the bed holding temp, either via Luban or via the touchscreen?


For the life of me, I can’t figure out how to start the automatic leveling routine via Luban.

You have to be connected with usb-cable on COM port (wifi doesn´t work for this).

I just don’t worry about it.
I figure that it stays close enough to the temp for long enough.
I set it to 65 (generally my bed temp for printing is 60) and then do the calibration right after it hits that temp.
Haven’t had any problems doing it this way.

Maybe I should use my temp gun and see how much it actually drops.


1 Like

I do the same as @sdj544 - heat to 65ish. It might drift back down to mid-50s by the time its done (in the enclosure, A250 in my case).

Just sharing some information I’ve found on the topic.

@Tone posted some sample gcode on how he did it here: Check Level Hot.gcode

He also has this sheet with information on how the auto levelling process works under the hood, it’s a custom wrapper around G29, and you can’t just call G29 or, like you found out, it’ll crash. How to do a larger than 3 x 3 matrix level

I took a 10x10 grid using a micrometer at both ambient and at 60C, and which the movement wasn’t much, the center of the bed raised 0.05mm and the corners moved more. I’ll try and format my findings later and update this.

I talked with someone who suggested using a macro to use the built in G30 single point probe in a grid, but turning the bed off immediately before taking the reading, as the electrical current in the heater can mess with the induction probe’s reading. I plan on trying that too, as I have noticed the bed moves a decent amount as it heats and cools, and it would allow for taking more readings at a more constant bed temp.

it would be neat if the bed could heat during the level but only on travel moves on X and Y not Z, that would help it maintain its temp / shape longer.