Mesh bed leveling issues with IR Sensor

[V3DPrinting]

Hi

I upgraded my cartesian printer (Ultimaker clone) from a capacitive sensor to IR sensor directly plugged into my Duet 2 Ethernet running Firmware 2.04.

No issues setting up the sensor, nor calibrating it.

But making a mesh bed leveling (G29) on a 25 points square surface (250 mm) always leads to a tilted bed from the front to the rear with a deviation of 1 mm or so from the front edge to the rear edge.

I've done a careful manual bed leveling with the bed and nozzle at normal working temperature, on a clean glass plate with no coating over a black matte cardboard.

So I am sure the bed is perfectly leveled against the gantry, but the probing gives a different view.

The printhead is guided by 2 LM6UU on each axis which are in good conditions, so no tilt suspected.

Has it something to do with temperature ?
My previous capacitive sensor was having a bias with temperature and derives over the probing.

Thanks for the feedbacks

[dc42]

The IR sensor is not temperature-sensitive. The height map looks quite flat, so i think the bed surface is OK for the sensor.

Can you provide some photos of your printer, so that I can see how the Y axis moves?

In what direction and by how much is the sensor offset fro the nozzle?

[gtj0]

Did you do the levelling following this guide?
https://duet3d.dozuki.com/Wiki/Using_the_manual_bed_levelling_assistant

If you run it a few times, are the numbers converging?

[V3DPrinting]

@gtj0 said in Mesh bed leveling issues with IR Sensor:

https://duet3d.dozuki.com/Wiki/Using_the_manual_bed_levelling_assistant

Sorry for the late reply

I don't use the leveling assistant.

I level my bed the old way, moving the nozzle close to the 3 adjusting screws, using a sheet of paper to fine tune.

Doing the tuning twice is generally sufficient to have a good leveling.
I will set up the manual assistant in the near future, at it will save me some time.

[V3DPrinting]

Sorry for the late reply, busy period till the holidays break.

@dc42 said in Mesh bed leveling issues with IR Sensor:

The IR sensor is not temperature-sensitive. The height map looks quite flat, so i think the bed surface is OK for the sensor.

Yes the measurements are pretty repeatable.

Can you provide some photos of your printer, so that I can see how the Y axis moves?

My printer is a Mankati Full-scale XT Plus, really a Ultimaker 2 clone.
Y axis is mounted on two linear ball bearings (LM6UU japanese industrial grade), side by side, on a 6 mm rod.
So bearing is on a 38 mm length, minimizing the tilt of the printhead.
Same on X axis.

In what direction and by how much is the sensor offset fro the nozzle?

The offset from the left nozzle is X + 41,2 Y + 11,25. Zero been on the nozzle tip.
Only the rear of the printhead has sufficient room in order to keep the build volume.

[V3DPrinting]

@dc42 Is this mesh probing error being fixed in the 2,05 or 3 FW versions ?