Need TAZ help, please

I am issues with my Workhourse. Printed fine before 2 year Covod lockdow, but suffered while in the hands of others while I owrked remotely. I use Polymaker Polylite 2.85, and am experiencing serios adhesion issues. Note the bottom of the attached print. Also, after about 50% or so, filament stops extruding.

I think your Z axis offset may be set way too high. It means that the first layer is printed above the bed rather than being pressed onto it. I’m not sure how you adjust it on the workhorse, but on the Taz 6 there is a setting that enables it to be adjusted while the first layer is printing, which enables you to get it pressing the first layer down onto the bed.


Your first layer is probably EITHER (a) too higher or (b) under-extruding.

From the looks of things, I’m thinking it’s probably ‘a’ because other areas of the part don’t appear to be under-extruding (I don’t get a great view of the side … but from what I can see it looks like the rest of the walls are ok, no?

The factory default Z-offset is -1.20mm for the glass/PEI bed (this would not be valid if you’ve switched to the flexible bed). The bed-leveling washers that are used to probe are 1.5mm thick … so the Z-offset has to be a negative value (the probed washers will be treated as the Z=0 point and then get adjusted by the offset to create a new Z=0 point that should be on the glass/PEI bed.

If you are running firmware (which is the latest version of Marlin for the TAZ Workhorse) then you’ll use the flexi-knob on the graphical LCD panel and navigate to Configuration → Probe Z Offset and you can view or change the value there.

BTW, if you are not running the latest firmware, make sure you’ve downloaded the latest version of Cura LulzBot Edition from the website (because that’s where the firmware is located), connect your computer to the printer via the USB cable, and in Cura LulzBot Edition go to Preferences → Printers → pick the right printer → Update Firmware and it should offer to update it to the latest.

You have the option to update EEPROM settings and if you do that it will over-write the Z-offset and Steps/MM for the motors back to factory defaults.

It is normal to need to tweak the Z-offset from time to time based on the filament you are using. When I print using flexible filament (e.g. PolyMaker PolyFlex) the Z-offset usually needs to be a tiny bit higher (I use -1.10) than when printing with PLA. Some filaments need a bit of “squish” to stick to the bed. Other filaments need to be more gently laid to the bed (not so much “squish”).

I’ve attached a tiny test disk (it prints in 1 minute) that I use to validate my Z-offset. This is a circular disk measuring 30mm diameter by .25mm thick. Set your 1st layer hight to .25mm and slice it … then print it.

30mm x .25mm test disk.stl (3.8 KB)

You want to see that the rows of layer lines are neatly laid down row after row with no gaps. If the Z-offset is too low then you wont have gaps … but you’ll notice the nozzle prints each row too wide and it not only meets the layer next to it … it usually pushes the filament up a little and I see little fins where the rows meet.

It’s a very good idea to own a set of calipers to measure parts when 3D printing. If you have calipers, measure the thickness of the part to verify that it is very close to the .25mm layer height. It will often not be bang-on accurate … but should be close. e.g. if you get something like .23 or .28 because if you re-measure the same part in many different locations you’ll get a tiny bit of variation … I might not fuss too much about that. But if you’re getting .15 or .35 … then you’ll need to change the Z-offset to get it dialed in.

Also … if you see wrinkles in your first layer then it means you are either too low … OR … you could also be over-extruding.

There is a test you can perform to make sure the extruder is not over-extruding or under-extruding. You can calibrate the “E-Steps” (extruder steps per millimeter).

When I do this, I check the idler-arm tension to make sure the tension is adjusted to what I’d normally use. I ALSO run this test with the filament heated to whatever temperature I will ACTUALLY use when printing a job.

With a couple of important caveats (there are a couple of errors in the documentation), the instructions are here:

HOWEVER … there are a couple of errors in that document.

On Step 9 it says to use the M501 command to view the current E-steps … the correct command is M503. (You can look up any G-Code command here: Gcode | Marlin Firmware )

On Step 10 it uses incorrect math to correct the E-steps.

The correct math is:

New_Value = (Old_Value ÷ Measured_Extrusion_Distance) X 100

e.g. if the previous value was 420 (the factory default) and you measure that the printer only advanced 98mm of filament instead of 100 then the math is:

New_Value = (420 ÷ 98) X 100

This would get you to 428.57 … so you would round that to 429 as the NEW value for E-Steps.

The math works regardless of whether the printer under-extrudes or over-extrudes.

The rest of the steps in those instructions are correct. Re-run the test after adjusting to make sure you are happy with the results … then save them to non-volatile memory using the M500 command (as explained in the document.)

THANK YOU so much for this infp. I set z to -1.0 and got good results. Trying the test file next