Oddblobbs :) Looking for some assist to settings

dc42

The blobs may just be due to insufficient retraction. How long is the Bowden tube on your Kossel? Do you have clips under the collets at the ends of the tube to lock them in place?

Incom

Did you manage to solve your blob problem?

I've recently converted my Hypercube to Bowden (Titan with a V6 Hot End), and I'm getting blobbing on my Benchys very similar to yours. I've been able to determine the blob happens at the start of the outer perimeter as the nozzle moves from the inner perimeter, so I'm pretty sure it isn't retract related because there is no retract move at that point.

I've tried just about everything I can think of (tweaking temperature, extrusion multiplier, pressure advance, speed, acceleration,jerk, retraction etc), but I can't get this blobbing to go away.

Hergonoway

if you use simplify3D try to add a wipe movement of 1mm for start and check "retract during wipe movement" you should get improvment on stiching between layer. If blobs appears elsewhere (corner for exemple) you'll need to tweak up jerk and acceleration and eventually use pressure advance settings if you've got bowden over 30cm.

Incom

Hergonoway my hero!

That has improved things a lot (1mm wipe and retract during wipe) - still not perfect, but I can tweak further from here.

I've tried those settings before, but obviously not in the right combination. I thought it looked like it needed a retraction at the end of the inner perimeter, but hadn't fully comprehended how the wipe worked.

It is quite a long Bowden (approx. 55cm Capricorn tube), so I was anticipating some nozzle pressure problems.

Thanks again.

dc42

@incom said in Oddblobbs Looking for some assist to settings:

It is quite a long Bowden (approx. 55cm Capricorn tube), so I was anticipating some nozzle pressure problems.

I would expect you to need at least 4mm retraction to avoid getting blobs just before travel moves, and possibly as much as 6mm. Less if you use pressure advance.

Hergonoway

@dc42 +1

when I had a bowden it was 60cm long of capricorn and I used 4.5 mm of retraction.

leif

Thank you all for great suggestions. Sorry for late reply, but was on short holiday I will give it a try later on today. I use S3D, but was wondering if there a way to adjust the settings "live" while printing?

T3P3Tony

@leif you can change the pressure advance settings while printing. In fact this is a good way to tune it.
Just send:
M572 D0 Snnn where Snnn is the pressure advance setting.

If you want to change retraction during printing then you need to use firmware retraction (G10/G11): https://duet3d.dozuki.com/Wiki/Gcode#Section_G10_Retract
If you use that then you can change the retract length on the fly using M207:
https://duet3d.dozuki.com/Wiki/Gcode#Section_M207_Set_retract_length

This thread talks about setting up firmware retraction in S3D:
https://forum.duet3d.com/topic/389/setting-firmware-retraction-with-simplify3d-slicer
note that it is a little old so S3d may have moved on.

Phaedrux

@t3p3tony said in Oddblobbs Looking for some assist to settings:

note that it is a little old so S3d may have moved on.

That's being very generous to the speed of simplify 3d development.

Hergonoway

Note that using G10/11 won't handle "wipe during retraction" option in S3D.

I'll suggest you to use this model : https://www.thingiverse.com/thing:909901

Add it X times in S3d and customize each process with different retraction settings. (Don't forget to print with piece by piece option with enough clearance) the model is small it'll be easy.

At least you'll end up with a clean base to fine tune reactions with more complex models.