Is my nozzle partially clogged?

[Jules]

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.

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.

(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.)

Can someone explain the exact different with the z height mechanism and firmware compensation on the Rev E. machines?

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.)

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.

[darkstarone]

Thanks for all the information!

Not sure if this is a recent thing but the latest version of S3D does seem to allow you to specify the offset down to the hundredths, but I do like the idea of tweaking it directly from the console, seems like that would be much faster to dial it in.

So my approach so far has been to leave the Z-offset alone and let the printer do it's thing as far as maintaining that perfect gap. I just purchased some metal feeler gauges and locked it in one last time just to be sure (0.13mm same as the included paper one).

I will try your settings though and I think I will leave PETG for printing out parts and things like that.

Here is how the part turned out at 0.1mm. It's actually not too bad I think, if you can look past all the burn marks

The other one is a box lid I printed out at 0.15

[Jules]

Lord! Those must have taken forever! (They look good though.)

Not sure if this is a recent thing but the latest version of S3D does seem to allow you to specify the offset down to the hundredths

Yes, it does, (that's not new), but with the Rev.E machines, it has no impact (in other words, no physical change will actually occur) until you get to adjustments of 0.1 mm or higher. You can put a 0.04 mm adjustment in the Z-Offset slot and absolutely nothing happens.

Try it and see sometime, if you have a few hours to kill and want to give your calipers a workout.

With the older machine setup, adjustments that small do impact how tall the prints printed, and the effect was instant and measurable. (It's how we adjusted the gap on the Rev C and D machines. It changed when they shifted the Z-Stop to the bottom, and my personal (unproven and unsubstantiated) belief is that the formula that they use in the firmware to bring the bed up into position rounds the number somehow.)

[darkstarone]

Ok that makes sense, I see what you are saying. Thanks for clarifying that.

I think I have probably observed this behavior now that I think about it while previously adjusting things.

Thanks again.

[Jules]

De nada! Have fun!

[darkstarone]

Can you clarify whether you are referring to the Global Z-offset setting in Simplify 3D or the origin offset?

I did some tests and it would seem that the z-offset setting works perfectly fine, even down to the hundredths.

Am I looking at the wrong setting to adjust for my problem here?

[Jules]

Global G-Code Z-Offset.

Which version of S3D are you using?.....The last one I tested it on was v3.02. Maybe v3.10 has been modified, which would be great. (Or the -.07 mm adjustment has been rounded to 0.1, because that 0.03 mm difference is just about at the accuracy limit of a lot of calipers.)

Go ahead and test the 0.02 mm adjustment increments with your print and see if it gets rid of the hairs. No harm in trying and you can always change it back.

(I can't even look at it until tomorrow at the earliest, I'm halfway into installing dampers on the Rev. E, and still don't have the screws I need because my appointment ran long and I had to get back.)

[darkstarone]

I'm pretty sure these calipers are fairly accurate since I've tested them extensively with metallic feeler gauges. Maybe the issue has been fixed in 3.1.0? That is the version I'm running.

[Jules]

Maybe so. I'll run a few tests later in the week, I've got v3.10 loaded up now, but the machine is temporarily out of commish.

[darkstarone]

So let's assume for a moment this has been fixed. I adjust my z-offset to get a nice perfect layer for my PETG material. My height now measures less than perfect, do we just live with that difference and call it within tolerance?