"Dimples" appearing since upgrading to Titan

I recently upgraded my printer from a Mk8 with dying motor to a (non-Bowden) Titan with E3Dv6 using an 11Ncm 0.9-degree motor (calibrated e-steps are a whopping 1674!). (The old motor was a lot bigger and 1.8deg.) Although I'm still tweaking settings, I'm pretty much to the point where there's only one issue remaining: bizarre "dimples" at the end of each layer:


(This is PET running at about 45mm/s and 243C, if that matters; note that I have not tried any other filaments yet since installing the Titan, but this never occurred with this or any other filaments prior to the upgrade.)

The smaller motor seems to have enough power - I have yet to have any "clicking" or other indications of extrusion issues beyond this due to lack of torque. I've messed with all the LCD-changeable firmware settings I can think of (acceleration and jerk primarily; I admit that I'm not too knowledgeable in the firmware area), I'm using S3D and have tried every combination of settings imaginable, and no matter how awesome I get the overall print, I cannot get rid of these tiny little indents. Bolts have also been loosened enough that I seriously doubt they are the issue.

I'm 99% sure the dimples are at the end of the nozzle movement, not the beginning (settings-changes affecting the start of the line pretty much universally make the whole print worse), and since S3D won't let you set coasting distances to negative values I can't kludge a fix that way (enabling coasting but at 0.0mm doesn't help; I even gave that a try).

Everyone I know is stumped at this point, so now I'm moving on to those that I don't know. I've spent at least 10 hours this point, probably double that, and am completely out of ideas. Hopefully someone here can help me solve this!

Cheers!

 

That's at 0.6mm. I've actually gone so far as to completely turn retraction off, and as expected it created blobs and other artifacts...without doing anything to fix these dimples.

Here's the important(?) settings used on this print; I might have slightly modified them since printing this thing, but they were very close (and in any case these settings here appear to be optimal print settings with the exception of the dimpling.) -

 

If your other settings are correct, no. If I set it to optimized points, or to "closest to x/y coordinates", I end up with a really horrible vertical seam. That never happened with my old Mk8 extruder, nor does it happen on my other (cheap) printer. This specific dimpling is definitely post-Titan upgrade.

 

(Sorry, for whatever reason I'm not getting email alerts...or Gmail is filing them away into some strange corner of my folders. Anyway, that explains the lack of quicker replies...)

I just spent a ridiculous amount of time trying to find pre-Titan prints that have areas of 100% "roundness" and, well...the only round objects I can find were printed right at the end of the Mk8's lifespan, when it was failing badly enough that the only way I could prevent huge gashes from appearing was to print extremely slowly and at unusually high temps. I didn't think about it until now, but they came out shiny as compared to the duller color I get now, so I'm now wondering if the slow+hot effectively "melted the dimples out"..? Now, I've got quite a few prints that are *almost* completely round, but they have at least one "corner" (even if it is beveled on the model) where I can't discount evidence of a seam. (It's too difficult to know for sure.) I could post pictures but since its not definitive I'm not sure if there's a point.

As for my other printer, although I can print round test objects, apparently I haven't printed 100% round objects before as my settings go from Great to Crap the moment I print a completely circular object. I thought I could, and just tried doing so with a few different settings, but for whatever reason my normally-okay coast and retraction settings suddenly turn awful when dealing with a completely round layer.

So...I'll post once I (re?)verify that extra restart causes issues rather than fixing the dimples, but otherwise I'm starting to think that you guys are right, dimples were probably always there, but the lesser quality of the prints "covered them up" as compared to the much-more-precise prints I'm getting from the Titan...

EDIT: Extra restart is definitely causing problems, so the dimple must be at the end of the line. So I guess I just spent a week trying to fix a problem that has always existed, but for whatever reason(s) I never realized it until post-Titan-upgrade. *SIGH*

 

On my round test object, the only visible difference between your suggested changes, my original changes, or (as a 3rd test) completely disabling retraction, is that the changed or disabled retraction settings create blobs on the inside of the print. Although the changes might be a tiny bit better dimple-wise, the blobs that form on the inside appear to effect the outside layer in their own right, offsetting any benefits.