What about different traveling speeds over land/air?

[geert_2 558]

When the traveling speed through the air is high, this easier breaks strings, and creates less chance of oozing and blobs when landing on the next part of the print. But when traveling over "land" (thus over the already printed model parts), this causes ugly dull lines, or even causes the printer to leave behind a sort of "morse code". On the next pass, the head crashes into this morse code, and it accumulates on the nozzle, and then leaks and causes hairs.

When the traveling speed is identical to the printing speed, e.g. 30 or 50 mm/s, traveling over land gives a much smoother surface, without dull lines and morse code. But then you may get more oozing through the air.

So, what about different traveling speeds for moving over land and through air?

- Traveling speed over land: 50 mm/s default, (or "0" for identical to printing speed)

- Traveling speed through air: 150 mm/s default

Edited March 15, 2017 by Guest

[bagel-orb 61]

Cool idea!

[neotko 1,417]

Cool idea!

 

I highly disagree. Slow travel path for combin moves will cause the drip to increase and unless someone makes a math formula to actually know how much drip/mm/heat/viscosity is lost, you will get a bit of underextrusion when the extruder resumes to print.

[kmanstudios 1,120]

If one were to factor how much the filament has moved by tracking the feeder movement, it could work like a retraction between layers or during changes.

Yes? No? Over my head and too stoopid to know it?

[geert_2 558]

 

Cool idea!

 

I highly disagree. Slow travel path for combin moves will cause the drip to increase and unless someone makes a math formula to actually know how much drip/mm/heat/viscosity is lost, you will get a bit of underextrusion when the extruder resumes to print.

 

Hi neotko,

From a theoretical viewpoint I do understand your concern. But in my tests, I haven't noticed this problem yet. But I will look out for it in the next prints.

Practically, for PLA I usually use the default speeds of 150mm/s travel, and 50mm/s printing, which gives good results. Here, a low traveling speed would have little benefits.

But for transparant PET materials this high traveling speed sometimes causes a dull line, thus an ugly opaque line in the otherwise "frosted glass" transparant appearance. So, here a slow traveling speed gave me a much better result, since the oozing-line was now also transparant, no longer dull opaque.

PET is more sticky and "rubbery" than PLA, and tends to build up on the nozzle (at least the ones I have). So, when moving fast, the "morse-code" that is sometimes left behind, accumulates on the nozzle, burns, leaks, and causes these ugly brown spots. Here too, a low traveling speed outweights the disadvantages. At least for me, but other people have the right to see things differently, of course.

So, for PET and co-polyesters, I now use the slow traveling speed, identical to the printing speed. For PLA, I use a high traveling speed.

So, in any case, this should be a user-selectable option, and not be enforced.

[neotko 1,417]

Oh indeed I see what you mean now. Indeed my experience is more focus on fast print speeds 70mm/s where the pressure is high and I need to keep everything undercontrol to keep getting high quality.

Indeed the viscosity of the material is a very important element when moving on combing. For example for recreus filaflex using less than travel speed for combing moves would be a nightmare since it flows so fast that you need to keep controlling the material at every point. For low temperature prints or slower prints or less viscosity materials using slower travel speeds could make sense indeed, but also you would be 'neosanding' the print on only some areas. For pla doing that makes the print matte but for pet I trully have no idea what effect. The first thing that comes to mind is that it might 'burn' and go brown.

But indeed, you are right, having the setting available to change for combing moves, could be an interesting thing for some prints.

[geert_2 558]

... Slow travel path for combin moves will cause the drip to increase and unless someone makes a math formula to actually know how much drip/mm/heat/viscosity is lost, you will get a bit of underextrusion when the extruder resumes to print.

 

Hi neotko,

This week I first encountered this phenomenon you described, when printing in PLA at a bit higher temperature. Good prediction!

So it seems to happen occasionally when the material is quite liquid due to higher temps, and when there is a long travel through air. Never had it with my PET up till now, since that stays more rubbery like chewing gum, and doesn't leak so much.

So traveling through air definitely benefits from a fast move. While traveling over land for PET and PLA at low temp, seems to work better with slow traveling speeds, to avoid the "bits of morse code".