TAZ 6 - Weak bed adhesion compared to Mini

I’ve owned a mini for about a year and a half. I just got a TAZ 6 a few months ago. One thing I noticed right away is that the print surface adhesion isn’t nearly as good on the TAZ 6 as it is on the mini. With the mini, I need to almost pry parts off the plate when they are done, but with the TAZ the parts barely stick at all. This is with ABS and almost identical settings when slicing for each printer.

Is this a common issue with the TAZ 6, or did I just get a defecting print surface out of the box? Any other people seeing this issue?

Post a pic of the bottom of a print… If the extrusion pattern of the bottom isn’t completely smooth with vague lines of adjacent extrusions, then the nozzle may be too far from the bed for the initial layer.

More than likely your Mini’s autolevel may have been off due to a dirty nozzle or washer surface. This affects the washer to nozzle conductance, and usually causes the nozzle to print too close to the bed.

You could also try giving your TAZ 6 PEI bed a light sanding to “reinvigorate” the PEI. Use a fine grit sand paper…

Yes, I have noticed this as well. I’ve also noticed the my mini consistently prints the first layer thinner (closer to the bed) than the value programmed which is why it might be sticking better. I don’t know if I have the latest version of firmware in my mini as it is over a year old. I asked Lulzbot for a copy of the mini firmware release notes, but they pointed me to the development site, if you find them on there let me know because I couldn’t. Tweaking the first layer height and increasing the bed temp has helped the first layer adhesion on my Taz.

It could be a cleaning issue on the mini too.

Personally, keeping things clean is the Achilles heel of LB’s auto-level process… its slick, but relying on electrical continuity through a part which will more than likely get dirty from extruding material isn’t ideal. At the very least, they should add a “wipe” in the end script to clean the nozzle while at true extrusion temp. Just put FSRs under the washers.

I’ll try putting both machines through a good cleaning, but I really don’t think that’s the issue. I’ve needed to pry parts off the mini starting with the first print of the rocktopus/octopus.

How are other people measuring the first layer thickness? Just print a single layer plastic sheet and measure it with a micrometer? I don’t actually have a micrometer, but I do have a decent digital ruler from Amazon that claims it can do 0.001 inches. I don’t know how much I trust that the accuracy of the ruler is that good though.

If it is a first layer height issue, I wonder if the issue isn’t simply that auto bed leveling works better on the mini then the TAZ 6. I can see how the much larger print surface would make it more difficult to make to make leveling work well.

BTW, I’ve found on the mini that the default gcode header doesn’t always wait for the bed to be completely heat before it starts printing. Sometimes the bed temp will be so low that I end up with a mess to cleanup. Lately, I’ve been manually setting the bed temp and waiting for it to completely heat before starting the print. It seems to make the auto level work a bit better.

The print starts right away because the mini start.gcode has an M140 command at the end, this sets the bed temp, but doesn’t wait until it heats to continue. If you change this to an M190 command, it will wait till the bed reaches temp to continue. I changed my code to M190 so the bed is a more even temperature. It does take longer to start printing though.

Take a look at the start.gcode on the Taz 6, it has an M190 command.

As for first layer thickness, dial calipers work. You can also not load filament, stop the extruder during the first layer print and then use a feeler gauge, just be careful not to get burned by the hot nozzle or bed.

Measuring bottom layer thickness it sounds like an exercise in futility (maybe I’m wrong, just my feelings on it).

Mainly I can tell bottom layer thickness (to low/to high) just by watching the first layer print. I generally how for over sticking though as I print difficult parts.

I would just print a test cube on both machines and compare the bottoms.

I have a theory that lulzbot has intentionally increased their z-height on the first layer on the Taz 6 to avoid parts from sticking to much. It’s no secret that the PEI sheets have bubbling issues that is only exacerbated by parts sticking overly well. Additionally I’d imagine a larger print bed on the 6 would be more prone to bubbling than the smaller minis pei sheet. Solution? Increase z-height so customers are less likely to damage the PEI.

I’m the first to admit this is just a conspiracy theory that has no evidence or facts to back it up. Call it a gut feeling.

Your solution would be to change the firmware and lower the nozzle. Or you can try sanding the PEI and try and increase your stick.

I just want to say thanks to everyone that responded. Many of the suggestions have been quite good.

As for the PEI issue and the Z height, it makes a lot of sense. I’ve had trouble with the PEI bubbling on the mini and it’s either expensive to replace(replacing the whole plate) or hard to do(scrapping the PEI off). Perhaps Lulzbot was getting too many people wanting a replacement machine during the warranty period due to the bubbling. A small Z offset would also reduce the risk of the print head scrapping the surface and causing real damage due to either people not knowing what they are doing or a failure in the auto leveling process. Perhaps in future versions, Lulzbot should make it a bit easier to replace the print surface.

Thanks again.

I can tell you that this is nowhere near the case. I got my TAZ 6 2 weeks ago and practically damaged the PEI trying to get the Rocktopus off. The skirt was a nightmare and I actually have a smooth groove in part of my PEI sheet because the z offset in the printer was too low. I did not have the same post-“first print excitement” with the TAZ 6 that I did with the Mini.

Using the panel my z-offset was set to -1.350 by the person who prepped/calibrated my machine. After some experimenting I have it now set to -1.100 and things have improved immensely.

What do your skirts look like before the print? Are they really flat and almost see through?

If your Cura initial layer setting height is .425 then stop a print after the initial layer and measure it. That is your first step.

Interesting that you can set the Z-offset through the pannel… wonder if this is the M206 (toolhead offset) or if they are using the M212 (bed sensor offset) commands set this offset. Can someone copy and paste the output of a M501 from the TAZ 6?

Also came across G10 P# Z## to set Z offset as part of start script. Could be helpful to folks… but probably need to nail down the command nomenclature…

BTW - How do you measure the initial layer? I usually have to scrape mine off which probably distorts the measurement… :slight_smile: