No, that's not a hardware issue, it's more likely a filament issue. There are different stressors acting on the plate with the different motions - they are always there, but some filaments show them more readily than others. ABS is an easy filament - it's more forgiving of not having everything set to exact tolerances. Unfortunately, PETG isn't. It's very fiddly. Once you get the settings correct, it prints like a dream, but frankly it takes some experimenting to get it set just right.I was printing ABS before, and didn't have any of these issues occurring in either direction, but I'm not sure if that is proof enough of a hardware issue not existing.
(Yes, i have noticed a difference in how bridging is impacted when it's performed in different directions. You're not wrong, but you might be smacking up against the limitations of the filament. Try slowing down the print a bit more.)
No, but I can direct you to the thread where the new bottom set Z-stop was developed. (Not being snarky here, but I can't explain it - I was not one of the original testers, and the thinking behind it is a bit above my pay grade.)Can someone explain the exact different with the z height mechanism and firmware compensation on the Rev E. machines?
viewtopic.php?f=10&t=3072
I understand how the new system works, and what steps have to be taken to adjust for specific problems in both the old system and the new one, and I know what the differences are. I can probably even tell you how to adjust the nozzle to get rid of the blobs with your Rev. E, but it's going to involve G-Code modifications, and I wasn't sure if you wanted to go that far. You will have to fine tune the Starting Height gap using G-Code, because the Z-Offset in S3D only works in relatively large increments (0.1 mm) for the Rev. E machines, and you will need to continue the adjustment of it using a much smaller increment. (0.02 -0.04 mm) That's why I tell Rev. E users not to bother with the S3D Z-Offset Adjustment - it can't be fine-tuned to the level that it needs to be. For most filaments, they are fine with the Starting Height set in the beginning. PETG takes a little extra work.
What you need to do to avoid the little threads that are created on the nozzle is "air-print" the PETG just a little. Since your initial problem was with incorrect tension and fill percentages, and you changed the Starting Height (aka: Z-Gap). You needed to get past that before the threads became a problem. Do not adjust your gap again - it's as close as you are going to be able to physically get it, and the print looks good with the exception of picking up threads.
Let me get back to you with the rest a bit later .....I have got to go feed my husband. (I'm gonna wind up divorced one of these days.)
Okay, back to business....
The threads are formed when the very tip of the nozzle just barely brushes against the top of the filament that has already been laid down. It sticks to itself very readily. (You can see it if you get down at eye level and watch the tip of the nozzle while it prints. For PETG, you should be able to see a fine line of air between the nozzle and the previous layer.) So you need to increase the gap size by from about 0.02 mm to 0.04 mm. Start with 0.02 mm, give it a try, and if it's not enough, add another 0.02 mm to the gap.
The Rev E. machines, due to the way the starting point is calculated for the first layer, need to be modified for small increments using Steve's explanation below:
sthone wrote:
From the Command Line in S3D
First Type M501 to read the EEPROM parameters
Look for the M206 line. (it should look something like M206 X0.0 Y0.0 Z4.20)
You can then adjust it using M206 Z[new value] (so add or subtract your .02 mm to what ever your value was to raise or lower the starting height)
and then M500 to save it to the firmware.
That should take care of it, but it might take a sample print or two to fine-tune it. Just use small increments.
One other thing - PETG prints best with taller layer heights. 0.1 mm high is too ambitious for me to have tried with PETG, and your print ratio at 0.4 mm wide for 0.1 mm high would be just about impossible to control.
Set your layer width to 0.47 mm, and your layer height to 0.25 mm. That's the sweet spot for printing PETG.