Initial tuning for corexy with 3 z independent z screws

coredump

Edit, here is why those multi start screws are my pet hate https://somei3deas.wordpress.com/2017/01/31/z-axis-lead-screws/

Also I read this and now want to find a way to adapt a 1:2 gear on my current screws. Or change them to a 1 start or threaded rod.

deckingman

You can also try using a wider first layer which sometimes helps - up to 200% of the nozzle width.

coredump

So I changed the belts, added a 300mm PEI cover to the bed, and that seems to have helped on some of the shift issues

The first layer problems still here tho. I am printing a big box for my duet now, and for the first layer to stick I had to print it with like 10 mm/s, on a Pei bed at 70 degrees. Still I get this:

In this the skirt is raising up on the border because when the nozzle goes throug there, it forces it up.

This is a photo of the first layer, as you can see the bottom part is very squished to the bed while the top part totally isn' t.

I tought that with a MIC6 plate, independent screw correction and mesh maps, I would not have to worry about it getting a correct first layer ever again, but it seems that I may be better manually changing bed screws since I can't reliably believe this printer.

whosrdaddy

What I first would look at is that your piezo probe is working correctly and is consistent.
I find it weird that you have to use the H parameter for G30 in bed.g.
Try to do G31's on the different bed.g locations and repeat like 5 times, you should get values within 10 microns, if not you will need to tune the probe.
If G31 is working as it should then do the same multiple G32's and see if the compensation values vary wildly or not.

deckingman

From those pics it looks fairly clear that the bed isn't level so I agree with whosrdaddy that you ought to check that teh probe is functioning as it should. If it's inconsistent then that would explain things.

coredump

Got some good prints the last few days. I had to use the bed compensation AND mesh leveling. I guess somehow I got a 6mm aluminum plate bent

Martin_S

After generating my own RRF config. g file I was having bed adhesion problems like you. What seemed to be the issue was that I messed up with the thermistor values. When the hotend was set to 235ºc it was actually 215ºc.

Try this value:

M305 P1 T100000 B4725 R4700 C7.06e-8 H0 L0
``` 

BTW, I'm also using OEM TitanAero with the stock thermistor cartridge.

coredump

I have the same values, but not the H0 and L0. What those do?

I got those values from the official E3D docs.

deckingman

@coredump:

…............................ but not the H0 and L0. What those do?

See here. https://duet3d.com/wiki/G-code#M305:_Set_temperature_sensor_parameters

BTW, the duet g-code wiki is a great resource if ever you have similar questions.

dc42

The H and L parameters are not generally needed for the Duet WiFi/Ethernet. They are sometimes needed on the older Duets.

deckingman

@coredump:

….................... I guess somehow I got a 6mm aluminum plate bent

Not necessarily. It is possible that the X Y rails are not truly parallel (tram) with the bed or that they are not truly straight. Either way, mesh compensation would work though.

coredump

@deckingman:

@coredump:

…............................ but not the H0 and L0. What those do?

See here. https://duet3d.com/wiki/G-code#M305:_Set_temperature_sensor_parameters

BTW, the duet g-code wiki is a great resource if ever you have similar questions.

Sorry, I read the wiki and I understood what the parameters do, was just asking why those values exactly

HikariNoKitsune

Lol this is probably a dead one, but this sounds almost EXACTLY the same issue I had been having with my printer when I finally bought a Duet WiFi and tried to get my bed probe working. When It would home/level, and I did the paper trick, everything looked perfectly fine. But when I would start a print, the nozzle would be anywhere between 0.3 to 3mm above the bed and sometimes below... scratched a freshly installed aluminum plate that day...

Anyway, I posted on here about it, and everyone suggested that it was because I didn't actually have the bed leveling action dictating the final Z height. As in, after it homed Z using the probe, it didn't actually 'save' the detected height. And so when it went to level the bed, it didn't have the proper height saved to begin with, and thus all the leveling showed my bed was 1-3mm below/above the expected Z0. Thus when it started a print, it'd float up in the air/dig into the bed...

I forget what the actual code is, and I'm not near the printer atm to be able to look at my configs, but I know there was some GCODE I had to implement after homing and after probing, that dc42 had told me to add if I remember correctly. It basically forced the Z Position to set based on whatever the sensor detected. Since then I've had nothing but amazing first layers print after print. Only issues I've had is when the extruder borks up and I gotta clear the ptfe tube...