HE280 Upgrade Calibration failure while heating hot end

[HComet]

Just finished doing the HE280 upgrade to my V2. Auto calibration seems to work fine as long as the hot end is off. As soon as I set the hot end to be heated then the auto calibration fails at random points in the middle of the calibration sequence leaving the printer frozen. I've tried using the calibration gcode remotely and from the SD card as well as the built in calibration from the LCD panel.

If both the bed and hot end are off then auto calibration works.

If the bed is on and the hot end is off then auto calibration works.

As soon as the hot end is on it always fails at some point in the middle.

The built in calibration routine always fails since it heats the bed and hot end.

Has anyone had similar issues? Is the auto calibration supposed to work with the hot end on?

I have seen I2C errors in the console when calibration has failed. Maybe when the hot end is on it is causing interference and interrupting the I2C signals?

[TwoTone]

I've read multiple times on the forum, calibration is done cold.

[Qdeathstar]

I wonder if it would be possible to calibrate cold, heat up, then probe once more for z-height......

[Mac The Knife]

Here is Guano's response to why it's done at room temperature: "
the probing routine must be ran when the machine is at room temp as we have said... the accelerometer is sensitive to lots of things. I'm pretty sure the amount of EMF the bed gives off is one of the biggest things that cause the probe to be false hit when trying to probe with the temps on, and this can be seen if you have a EMF detector on a cell phone, or if you put a cylinder magnet on the bed and turn the bed heat on, the magnet will align with the bed. This is why we say run the calibration with the heats off, and the machine cool (we say with the machine cool because the Z probe height in the eeprom has a negative value on it to compensate for expansion of the hotend and bed.)"

[HComet]

OK, Thanks.

I was confused by the new auto level function that is added to the LCD menu with the firmware upgrade. It sets the bed temp to 65 and the HE temp to 200 before running. I guess this is not part of the SeeMeCNC mods to repetier for the accelerator upgrade.

Although the HE heating expansion is easier to compensate for since it is roughly a point I would think that the bed expansion is less uniform over the surface of the bed. The calibration script could probably be tweaked to toggle the HE and bed heaters on and off. Heat them up then turn them off just before a probe then heat up again after the probe. The HE temp drops pretty fast but the bed temp drops fairly slowly so may work best with bed heating only. The Z probe height would need to be adjusted for this too.

In any case I'll try some prints using cold calibration and go from there.

[mhackney]

Oly verified that it is run cold in an email to me last week. I will be doing some investigation on the results once I get my machine and assemble it. Based on my experience with FSR probing (and this is full delta calibration with Duet firmware) I don't anticipate there to be an issue probing cold. Worse case as someone mentioned above, you could set the Z after heating. Another option is to bring everything to temperature and turn off the heaters and probe. That way you probe hot but do not have the potential interference issues.

[geneb]

Do NOT run the calibration from the front panel menu option! It won't work. The menu option should have been removed, but it hasn't happened yet.

g.