Z axis calibration issue

jumpedwithbothfeet

Evening all, I’m having real issues trying to calibrate my nozzle height, I’ve tried multiple guides and keep getting the same result the nozzle is still to high around 0.70mm to be exact I’ve done my trigger height like this -

M208 S1 Z-3 remove restriction
G1 Z1 probe to centre
Moved nozzle to the bed till just touching paper
G92 Z0 to define that height as Z=0
nozzle up 5mm and G30 S-1 to probe the bed carried out 5 times
Z axis reads 3.31 - 3.32 trigger height
G31 edited to read G31 P500 X45 Y2 Z3.31

But when I then move the nozzle to Z0 it is still around 0.7 to high, What am I doing wrong? do I need to put a z offset in?

jumpedwithbothfeet

Apologies should mention I’m using a bltouch 3.1, duet 3 board with sbc with the firmware updated!

jumpedwithbothfeet

Also! config.g
config-override.g
deployprobe.g
retractprobe.g

Phaedrux

What's in your homeall/homez as well.
Are you using G32/bed.g or G29 as well?

Phaedrux

Are you heating up the bed and nozzle before you touch down to Z0 on the bed?

For the BLTouch you may want to change your settings a bit to match this:

M558 P9 C"io7.in" H5 F60 T6000 A10 R0.5 S0.003 B0            ; set Z probe type to bltouch and the dive height + speeds
G31 P25 X45 Y2 Z3.31                       ; set Z probe trigger value, offset and trigger height

Trigger height of 3.3mm would indicate the mounting height is a little out of spec. Antclabs recommends that the bottom of the probe body should be ~8mm above the nozzle tip, which would lead to a trigger height of ~2mm. Not sure if this would also affect trigger sensitivity or just as a safety precaution to keep the probe pin far enough away from the print.

jumpedwithbothfeet

@Phaedrux i have repeated multiple time both hotbed and hot nozzle and cold, i have also carried out both G29 and G32 although i have no map currently loaded but if the z axis isn't where i want it to begin with i'm not sure it matters?

i had already measured the bottom of the Bltouch shell and it's 5mm to the nozzle tip so yes it is short but i'm using the original creality bracket and its non adjustable it can go down (shims) but not up, the trigger height is pretty consistent and worked fine before, but if you think that's the problem i will figure a way to move it higher.

homex.g
homey.g
homez.g
homeall.g

Phaedrux

G1 X-30 Y13 F6000       ; go to first bed probe point and home Z
G30                     ; home Z by probing the bed

I notice in your homeall that you're probing at a corner. It's a good idea to probe at the center of the bed and same with measuring the trigger height.

As for the probe height, as long as the pin isn't low enough to catch or the nozzle low enough to hit before the pin triggers you're probably fine.

How bout this, rather than using M208 S1 Z-3 you use M564 S0 H0 to allow moving the nozzle to touch the bed. Just in case there's some reason M208 isn't behaving as expected.

Is it consistently 0.7 too high? Even after restarts etc?

jumpedwithbothfeet

@Phaedrux apologies for not replying sooner only just back from work, I’ve managed to get a temporary replacement mount for the Bltouchto hopefully move the sensor to 8mm, and I will adjust the homing to the middle of the bed.

It does appear to replicate the 0.7mm height each and every time which is why I’ve assumed it is me missing a step, I have probed the bed with G32 which showed my bed to be slanting quite a bit so I re-adjusted it but it’s still not perfect but much better.

I have also tried M564 before as I read a post DC made elsewhere on the forum it didn’t seem to make a difference unfortunately.

I’ll move the bed homing and change the bracket and let you know the results if you think of anything else please let me know!

jumpedwithbothfeet

config.g
homeall.g
homez.g
homey.g
homex.g

Phaedrux

@jumpedwithbothfeet said in Z axis calibration issue:

I have probed the bed with G32

What do you have in bed.g? just G29 to do a heightmap?

PaulHew

Just to keep continuity and this thread updated, I had a private chat with @jumpedwithbothfeet .
The conclusion was to run the Duet3 in standalone mode to see if this helped with his board freezing and rectify the homing issues he was experiencing. He has / had a Pi3 connected.
I have not heard back from him as of yet, (no news is good news??!!), I hope to hear from him tomorrow.
I have asked him to update the thread to let us know his findings.
Paul.

jumpedwithbothfeet

@Phaedrux, @PaulHew , I think I have found out what the issue is or issues! The first was the sensor height after it was moved further up, the nozzle will now home correctly and the correct distance to the bed!

The other issue which I’m sure contributed to both the z cal and my board locking up was I’m sorry to say bad workmanship, after we spoke Paul I started shift stuff around for the standalone, thats when I saw the Z axis driver plug pins where not sitting in line it’s plugged it fine when you pull the plug they are all aligned, all have continuity with no shorts but some solder got further into the pin causing a poor connection!

I’ve now redone the plug and so far so good, I’ve Carried out G32 and will attempt a print shortly to see if there is any difference.

Either way I can’t thank you both enough for your help, feel like I might actually now get somewhere!

I’ll update the thread post print!

Jim

PaulHew

Jim, that is good news.
Keep us updated and if you need anymore verbal support, please do not hesitate to call.

Regards,
Paul.

jumpedwithbothfeet

@PaulHew its Finally printing! It’s the worst 20mm calibration cube that’s ever been made but it’s printing!, It still needs the z height sorting as a lot of baby stepping was needed and the nozzle has also grazed the glass bed, the x axis and extruded steppers are also running hotter than I would like so I’ll reduce the current some more, and then start more calibration I guess!