Not sure if this is a Z-offset issue or a bed level issue, or a bed flatness issue. I’m attempting to print a large spiral and the first layer appears quite good except in two areas. The upper right portion of the bed has a slight issue and the lower left is terrible where the filament is either not adhering properly or something else.
The bed was cleaned with iso-alcohol and a thin coat of glue stick applied. Nozzle temp is 235c and bed temp is 80c. First pic is upper right, 2nd pic lower left.
Any thoughts?
Thanks, Mike
Interesting. A print that big will surface any problems with bed levelling that might otherwise go unnoticed. Since the issue presents itself at opposite corners, it could be a tilt not properly offset by the autolevel process. Have you shimmed the bed on your taz?
Hi Ryan,
Thank you for the response. Here is what I did since I posted this some 10 days ago, and my findings. First, I believe you are correct that there was a tilted bed situation and it was not compensated for during the auto bed leveling. Also note that PLA is a little more forgiving on the first layer while PETG with glue stick did not like that difference in bed height, hence my post.
I recently purchased the Wham Bam magnetic bed with removable PEX flexible steel bed. My original PEI bed with about 2 years of use needed replacing so now was a good time to remove it and install the Wham Bam. After installation my test print had similar not-so-good results. I removed and inspected the Ningaflex bed corners and found the front right was a bit more squished than the front left which suggests the front right corner of the bed being a little low. The rear bed corners had similar differences with respect to the rear left and rear right. I swapped the front bed corners and also swapped the rear bed corners. Reinstalled the washers and made another test print. I was much better but still a little off. I decided to Print new bed corners out of PETG. I replaced the front right bed corner with the new PETG one. I did a test print and it looks real good so that is where I am now.
The picture shows my TAZ6 with the new Wham Bam steel bed and you can see the new blue bed corner on the front right. On top of the bed I show the original Ningaflex bed corner along with a spare blue PETG corner. The test print as shown is a PLA print and I inserted blow up images of the front left and front right corners. The first layer is near perfect in my book. Since then I completed the large spiral print in black PETG. All is good now! Side note: I printed a couple of ‘L’ brackets which are clipped to the rear of the steel bed frame for easy placement of the flexible PEX steel sheet.
Regards, Mike
Glad you solved it!
I also recently added a magnetic bed (PrintedSolid) when my PEI needed replacing. And I also had to create new corners to compensate for the difference in thickness without the PEI sheet. I prefer this setup on my lulzbots for one big reason: the less I have to physically pry-off parts (I print a lot of PETG), the less the bed gets force applied to it that might impact its bed tilt metrics. I run a bed leveling routine as infrequently as possible, and the magnetic bed does help keep the bed level unchanged across prints. Enjoy! 
Thank you.
I too hate to pry-off parts with enough umph that may possibly alter any bed leveling not to mention gouging the PEI surface. And, I really don’t care for PLA however I do like PETG for making prototypes. FWIW, I recently discovered a really nice PLA from 3D-Fuel called Pro PLA. It prints real nice and is easy to sand and drill if needed. Might be worth checking out. (Note that I have only printed with Pro PLA on my 2nd printer, a Prusa MK3.)
My new Wham Bam magnetic bed + the flexible steel sheet with PEX layer sits a little over 2mm above the glass bed, and, is around .33mm above the leveling washers. In other words, what was a Z-offest of around -1.18mm is now +0.54mm. So far I’m leaving the height positions of the homing button, wiping pad and leveling washers alone. The only alteration I did was replace the front right bed corner with a newly printed PETG one.
-Mike
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