cartesian and disortion correction

boelle

So i got a new heat plate and probed it... much better

but one strange issue if i enable disortion correction, first layer is ok, but for the next layer nozzle goes down and not up. This makes the extruder start grinding filament as it can not get rid of filament

config: https://pastebin.com/6G17KdGH screencapture from online config tool: https://imgur.com/a/ivLyK bump map: https://pastebin.com/afEUgXXF i'm sure this is my fault some how :-D

Repetier

Yes, looks like your fault:-)
Values should swing around 0 and not 2.2. After all you reduce correction in teh next millimeter to 0 from 2.2mm. So for 1mm up it needs to go 2.2mm down, just as you said.

This happens normally if z probe height is wrong. Best is running G32 S2 and then G33 directly afterwards (if extruder can switch to probe). That way it uses the height based on same z probe height and should be around 0.

My guess is that for homing you do some tricks to compensate a wrong z probe height but G33 is not aware of this.

boelle

I do not do tricks for homing, but my Z limit switch's are top mounted so i just adjust the Z max height to get the first layer correct

But i will try and check z probe height, i prop. forgot that

Did the config look ok otherwise?

Repetier

Exactly that is the trick. Firmware measures distance to top based on z probe height, so this correction needs to be added.

Or you have an other problem. Make sure to go back from max endstop so z homing is not at switch. If you move at top it will go up/down and must not hit limit switch.

MartinH

As you are homing to Z max, i think you need to do a G32 S2 to measure and set the Z length in eeprom and the follow on with your G33, this should set your matrix values closer to 0.

boelle

"As you are homing to Z max,"

Yes

" do a G32 S2 to measure and set the Z length"

why ? i just do a test print with disortion correction disabled and figure what Z lenght should be to get a perfect first layer

And G32 is that not autolevel? just asking to be sure

I use the disortion correction as i dont want/need to do an autolevel before each print

boelle

let me explain how switches are connected..

2 z max limit switches as i use dual Z stepper drivers and limit switches to they are in sync all the time
limit switch 1 is connected to Z max and switch 2 is connected to X max (i dont use it anyway)

Z probe is connected to Z min.

its a cartesian printer and not a delta.... without disortion correction i can get a smooth first layer, for now i have just printed a marvin so the area is limited

boelle

So if i understand both of you correct what i need to do is to home Z

then lower Z until probe triggers, the current Z pos. should be my probe height (Z_PROBE_HEIGHT)

i have my DISTORTION_LIMIT_TO set pretty high as the old bed was much bend, what is a reasonble value for that?

i have DISTORTION_START_DEGRADE set to 0.3 and DISTORTION_END_HEIGHT to 1, not sure if that are still good values

boelle

if i do that... ie home and then lower Z until probe is triggered it says 6,61 in Z pos

i just made a new and more solid bracket for it so might not be the same as before

is this my new Z_PROBE_HEIGHT number?

boelle

new bump map: https://pastebin.com/JFBWLrVp does this look more "reasonble"?

boelle

its strange.... a 250x210x0.2 test object gives these results

https://photos.app.goo.gl/pnVEbp8nk68Mvz802 the nicer one at the keyboard is without correction

is there anything i can do to improve things? or is the inductive probe just "trash" ?

Repetier

First MartinH is correct with saying Zmax homing should use G32 S2 to autolevel and save. This will additionally measure distance to top and set z length accordingly. Of course only works with correct z probe height.

Your idea to home go low until it triggers and z is the height sounds nice, but is wrong. This is only true IF it was already calibrated so z=0 is where it needs to be with active autoleveling. Under this special condition it would be the value you want.

Your correction output looks at least much better, but still is >0.8mm. For such a big value you might use at least 2mm of height to correct it down to 0 correction.

You could make a height map in host to see if heights get equal after enabling this at least. I think it includes distortion correction.

With inductive measurement make sure bed is off but still hot. The current changes result. I hope you have also a solid metal plate on top and do not measure against the bed heater wires with inductive probe.

boelle

the reason why i got really confused about G32 S2 is that i only want disortion correction and not auto level

but i will give it a go, just need to figure a way a dummie like me can do it. i read this page: https://www.repetier.com/documentation/repetier-firmware/z-probing/ but it just did not make sense, that is why i tried to disable any correction and lower Z until probed triggered. i now my Z lenght without correction so i thought it was a valid way to do it

boelle

odd

G32 is an unknow command

21:40:41.921 : Unknown command:N37422 G32 S2

21:40:45.058 : Unknown command:N37423 G32 S2

21:40:45.984 : Unknown command:N37424 G32 S2

boelle

ahh autolevel was not enabled as i had never had the need to enable it

flashing firmware with enabled :-) upps

boelle

i tried G32 S2

Got this odd error

22:16:02.691 : Error:Activating z-probe would lead to forbidden xy position: 5.000000, -20.00

22:16:02.706 : RequestStop:

22:16:04.486 : fatal:Could not activate z-probe offset due to coordinate constraints - result is inaccurate! - Printer stopped and heaters disabled due to this error. Fix error and restart with M999.

odd enough it still starts to probe

configuration.h: https://pastebin.com/c8BUXNxx</div>

boelle

figured it... i have to define where the probe can get and not where the nozzle can get... so that parts is ok now

reading https://www.repetier.com/documentation/repetier-firmware/z-probing/ the part that says using metal block... could that not be any object i know the the height of?

boelle

i'm very surprised. i initial just lowered Z and found that my probe height was 3mm

but with your guide i found it to be 1,989mm.. does this sound right?

i found an object that is 10mm high and the other numbers in the guide are

z0 10,611

zold 10

Znew 10,4

ZHold 3

boelle

gave the G32 S2 a go and it ended with

23:47:02.911 : plane: a = -0.0021 b = -0.0005 c = 3.5735

23:47:02.919 : Transformation matrix: 0.999998 0.000000 0.002082 -0.000001 1.000000 0.000548 -0.002082 -0.000548 0.999998

23:47:02.923 : Printer height:206.58

23:47:02.923 : CurrentZ:3.57 atZ:4.09

23:47:02.927 : Info:Autoleveling enabled

23:47:03.725 : X:245.01 Y:200.00 Z:2.953 E:0.0000

i can get the probe to within 5mm of all 3 edges but it throws a big warning if i try to go less that 0 on the Y... reason i want this is to probe all of the bed and there is enough room for the nozzle that i can go negative on Y

strange enough G33 allows to go that far but maybe G32 and G33 see things different?

boelle

new bump map: https://pastebin.com/skGPYs2C only thing that worries me is that G32 S2 does not get the probe to Y0 but only to Y20 where as G33 goes to Y0

and then of course if i got the probe height correct