Lulzbot Taz 6 Biqu H2 issues

General Software
21

The per-toolhead and universal firmware have different mechanical zero positions set so that with their most common toolhead, there is no M206 correction required.

Universal assumes you’re using a toolhead with the nozzle in the same physical position as their current toolheads (SE 0.5 series, M175v2, etc). Taz 6 Single Extruder firmware positions it so the Taz 6’s original toolhead has the nozzle in a different spot, so older firmware for it doesn’t need compensation with that firmware, but the Universal Firmware was (for a while) adjusting the M206 setting when you selected the toolhead from the printer’s menu. I am not sure, but I think now they try and do it all with the startup GCODE… but they don’t try too hard, since it’s a legacy unsupported printer now.

I honestly don’t remember which firmware I was using when I built the Biqu H2 toolhead, and had tried to get the physical nozzle position to match, so it likely will need adjustment.

22

I will check if there’s a m175specific firmware and if so I’ll switch to that, and save offset positions with M206 and save to EEPROM (which is what I did with universal iirc)

it does not have seperate firmware

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1x1x.25mm block_PLA_17m19s.gcode (139.9 KB)

24

Ok so startup sequence in summary:

  1. Home X and Y.

  2. Move to X-19 Y258 and home Z. This should position the nozzle directly over the center of the silver Z homing button. Is it over the center of the homing button? Does it do a second move in X/Y before moving the Z down?

  3. Firmware Wipe sequence.

  4. Raise Z.

  5. Move to first washer at X-10 Y293. This should place the nozzle in the front-right quadrant of the back-left washer. (note: this was only left in because lulzbot still had it… but realistically it should be moving to the front-left washer).

  6. Execute the G29 command for auto-leveling. This is the same command issued by the Homing option in the printer’s menu. It should move to the back-right quadrant of the front-left washer and touch down, before tapping the rest of the washers in sequence.

  7. Raise nozzle.

  8. Print commands begin.

Where in that sequence are you seeing the error? And is it possible to get a video of the attempted startup?

25

I think I know that the issue is, So, while not directly over the Z button it works fine, but i think it could be a discrepancy in the auto leveling matrix. when I issue it through the screen it goes from front left to back left while trying to print with the G-code it does the opposite, possibly giving false reports since it expects a different washer?

and In that seqence I see the error directly as it ouches the back left washer, it issues the command, goes to the back left tries to level touches the washer enough to make contact, and fails proceeding to a wipe sequene, and it does this fail loop 3-4 times before calling the “Leveling Failed Printer halted, please restart error message

So Gcode wise when I get home I’ll set the points tobe directly as you say (Center-Z button) and se the start of the leveling sequence to the front left washer instead of the back left

Also, for the positions could I just home the X and Y and then disable steppers and use the X and Y reading on the screen to manually adjust the posiiton in the code

26

Setting the points directly shouldn’t matter, since the probing points for leveling are all hard-coded into the firmware.

Which washer is your firmware trying to touch first? Is it touching more than one before erroring out?

What firmware are you running now?

If you disable the steppers, it will lose the X/Y position. Use the M206 to adjust as in the older messaging - Lulzbot Taz 6 Biqu H2 issues - #5 by Wrathernaut

27

it’s touching the back left first when trying to print, and when it makes contact with the first it immedietely fails and procceeds to a wiping sequence; does the squence tries to level at the same point again, rinse and repeat 3-4 times, then the error.

I’m running th Universal 2.0.9.013 off of Cura under the m175 toolhead as that is what this toolhead is made off of

28

When it makes contact is it pushing the entire bed down a good few millimeters?

29

No it’s the second it makes contact it marks it as failed and begins wipe sequence

30

A video of the attempted leveling would help.

I’m not thinking of a reason it would fail out on the first washer, unless the Z homing button isn’t being pressed by the nozzle properly, so the contact with the washer is too soon, and it’s outside as the allowable physical range for Z leveling.

31

I will get you a video here shortly

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Sorry I have been absent, I got busy with work and school and kinda just left the 3d printer to sit. I’m going to re-evaluate the code and printing on my new computer and get back to you with a video sometime this week.

33

a link to a google drive folder with four videos

  • a video of homing and m48 probe test
  • a video leveling the bed before running a print
  • start of the print, homing and leveling pt1
  • end of print/ leveling error

Edit: I added the benchy files that i tried to print and the configs from orcaslicer

and i leveled the gantry to the bed but it still fails. could it be the front to back ;level thats the issue? how would i level that out?

34

it also now fails any m48 probe test or bed leveling sequence now

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Homing and M48 (video 328) looks good, deviation of ~0.05 is good.

Bed leveling (video 713) also looks good.

Both of those, the nozzle is clean and cold.

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image391×346 17.6 KB

Print attempt, there’s visible plastic ooze on the nozzle:

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image292×203 41.5 KB

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image425×224 60.2 KB

Combine that with the complete lack of a wipe pad in the holder:

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image258×233 51.3 KB

So the wipe that the GCODE is trying to do from your startup GCODE is using a set Z height. It seems high, but you can tweak it as needed.

The attempted second wipe, where the nozzle is significantly lower, is the Z height for wiping that is hard-coded in the firmware.

Anytime there is plastic on the nozzle when it touches the washer, the plastic will insulate the electrical contact and affect where detection is. In the video, despite the lack of a good wipe, it seems to have a good contact with the first washer, as there is no visible deflection of the bed from the nozzle pushing down. It then moves to the second washer, and almost immediately fails out. This happens when the electrical connection happens too soon, or too late compared to the first corner. There (again) is no visible deflection of the bed from the nozzle pushing down, so I would guess this connection is happening too soon.

I see you have replaced the bed supports. Is the front of the bed lifted too much? It may be that when the bed is warm, its position changes just enough to fail leveling, when the cold bed succeeded.

Manually lower the nozzle to touch the back left corner, and note the Z position on the screen. Move it to touch the front left corner and compare the reported Z position. That should give you an idea of how far off the machine is seeing the two corners.

I can’t say what the maximum variance allowed is, but it appears yours is off by more than that amount when the bed is heated. Quick way to fix would be to remove the white bed support, and sand it down a little, or if you have another printer, reprint all four corners using lulzbot’s original model file in the appropriate material.

36

it could be the supports, i marked down the highs at which the nozzle encountered the corners, and the wipe pad was missing because on some tests it would plunge the nozzle too far into it, this time it did not.

the marked down Z-heights for each corener if this helps
(for reference the measurements were taken on the inside facing corner towards the print area)

back left Z:4.2mm
back right Z:3.8
Front Right and Left Z: 4.4 (they are the same as i leveled the tram based on that reference

37

Are those measurements done with a cold bed or one pre-heated? Since leveling succeeded with the cold bed and nozzle, that seems like a variable that needs to be accounted for.

A workaround is to manually level the bed while it’s cold, then remove the lines from the startup GCODE that level. It’s not great, since the bed might be shifting a little when hot vs. cold.

38

this was taken cold the next day, the level was taken after a homing sequence and based on using the built in moving the toolhead feature, just to get a basis from home, the measurements were marked down when friction was made between the nozzle and paper.

Like i said before it seems like a firmware/gcode issue but it’s an odd case because it homes properly and doesn’t fail when i reset the firmware based on whats saved to the EEPROM, but when it loads the gcode, it fails, and then lkeeps failing when printing or troubleshooting until i reset to eeprom.

I will see if i have other bed corners in the parts pile and if not I will check the Gcode once again for any errors, if that doesn’t work i’ll check level with the bed and see if i cant shim it level with the gantry and nozzle

39

proccess for reference done today:

  • reomved filament to stop contact issues

  1. Reset to defualts from eeprom

  2. homed nozzle, homing succeeded fine

  3. M48 probe test - success - deviation 0.012465

  4. level bed test (command through motion menu) - probe/level successful

  5. printed the same benchy from media for testing purposes of startup gcode or gcode related issues.

  6. Wiping sequence was within xy boundaries however z axis was above the strip not burried into to effecitvely wipe

  7. leveling sequence - succesful?

  8. printing looked to be within boundaries?
    Note: I don’t know why it is working now, this nect portion is me testing it WITH filament to see if printing still works correctly. starting with retests with a warm bed due to tests happening after test print with no filament.
    another note, the filament used may not be entirely dry i do not have a dryer on hand and it has sat for around 5 months in the time it took me to givup and come back to this project and it in turn rather brittle.

  9. M48 - success - deviation - 0.045127

  10. level bed test - success

  11. reprint benchy with filament - crashed into z button for unknown reason, no filament was present on nozzle

  12. after tunring printer off and on, homing went normally including nozzle wipe where x axis was off by a mm leading to it hitting the side of the felt wiper instead of the center.

  13. leveling bed failed due to same reason as before, touches corner and proceeds to wipign sequence

  14. reset eeprom to default again, and attempted to print with filament. before printing and after reset tested level bed function, proceeded as normal.

  15. printing 3d benchy from media after reseting, this time, with filament.

  16. Homing and wiping proceeded as before, the nozzle is off from the wipe and hovering above during wiping however it is working fine

  17. leveling proceeded as normal

  18. first layer of print was normal aside from the filament deploying to late do to me forgetting to purge.

  19. after letting print while i did summer school work the print came out as follows (image in drive folder)

conclusion - I think a discrepency and differing values in the eeprom and end/start gcode is causing the errors i am experiencing, I’m going to use the eeprom values for the home offset to slowly hone the nozzles position accurately and upload the same value to the startup/end gcode, as i beleive the difference may be the root cuase since the nozzle hovers above the wiping surface i think the margin of error is coming from that difference since it thinks the home offsets are where they arent causing the nozzle being higher/lower than expected is causing the failure.

I will make another post after i have tried and attempted these fixes. Thank you for taking time to deal with my novice tomfoolery, ove such a long span of time, i don’t think i would’ve got this far without you lol.

40

update after a little finagling and ai help Chat gbt either thinks its either M851 from the difference in code from the default settings and the ones i was using which failed, OR its a firmware thing that i’ll have to edit the base firmware to alter the nozzle positions on the M175v2 profile versus using m206 since m206 didn’t work

(I know using AI sucks but it was worth a shot)

currently i am seeing if i just use the base firmware with default settings, to print and maybe build a new wiping pad a couple mm to the left to keep things simple, so far it’s printing for the first time but like i said it usually works the first time so, i’ll test a second print and see if it continues to work, if it does, imma just kep it where it’s at and if the offset means i cant untilize the entire work area thats fine with me honestly lmao