Prusaslicer: [Feature Request] Coast at end

[Itox001]

It seems like Simplify 3D has figured this one out since a long time ago, and I think that it's one of the features that helps it get it's nice results, since it can help a lot with z scar, blobs at layer changes and that kind of stuff.

Basically, it stops extruding a certain distance before the current extrusion line ends, giving time to relieve the pressure in the melt zone and avoiding blobs, when filament flow is cut out.

[tcm0116]

You might want to take a look at the Pressure advance setting in the Printer Settings tab. This provides a more dynamic management of the pressure in the nozzle as the speed of the nozzle changes. It appears to yield grid results when properly calibrated.

[Sebastianv650]

Slic3rs pressure advance can't help in this case, because it will retract the filament to reduce the pressure after the move. At this point, it's too late to have the effect coast at end gives.

I played with pressure advance before I started the development of Marlins linear advance, based on my findings it's only a rough way to handle the nozzle pressure (but maybe the only one possible on the slicer side). It's usage wasn't improving the visual quality in first case, but it helped me to avoid gaps between the outer perimeter (printed slowly) and the inner one (printed fast). Without some extra start pressure, there is a gap for the first ~2cm until the pressure inside the nozzle has stabilised.

Therefore @Itox001 , you might have a look at Marlins linear pressure advance option. It's maybe not easy to understand and calibrate at the first look, but it will solve your problem as good as it's possible with any feature available at the moment.

[Itox001]

Hey Sebastian, I've actually read all of your posts on linear advance a couple days ago, and updated to the latest marlin (RcBugFix) to test it out. I actually did devote a day to calibrating it and setting it up right, and after tweaking I got a K of around 510 (got a 500 mm bowden). My calibration boxes were perfect, no bulging nor rounded corners and top infill had 0 under or overextrusion. But as soon as I tried to print something more complicated such as benchy, the first layer with the letters got underextruded hardcore, it seemed like the extruder couldn't keep up with all the movements and skipped lots of steps. The rest of the benchy seemed ok though, but not better than without pressure advance and proper retraction settings. After all that, I opened this issue, since I think that playing with extra length after restart and coast at end, we could get 70% there. Perhaps infill will not be perfect as with linear advance, but everywhere where extrusion starts/stops could benefit a lot.

[Sebastianv650]

That's true, a extra restart length calculated based on the actual volumetric flow speed and coast at end with a simmilar calculation (or a simplified fixed-value setting as known in Simplify3D) would be a good solution for printers having problems with lin_advance.

With that in place, the current pressure advance implementaion of Slic3r could be replaced completely.

[Disoculated]

There's a great deal of (old) discussion about this feature on the original Slic3r issues board:

https://github.com/alexrj/Slic3r/issues/3014

[bubnikv]

@Itox001

Basically, it stops extruding a certain distance before the current extrusion line ends, giving time to relieve the pressure in the melt zone and avoiding blobs, when filament flow is cut out.

Shall the coasting feature only be active just before a retract, or shall it be active for any stopping move?

Slic3r does a bit of "coasting" to hide a seam on any closed loop, but the coasting distance is fixed to 15% of a nozzle diameter.

[Itox001]

My guess is that it should be active every time it stops, since some stopping moves (such as layer change when "Retract on layer change" is disabled, or a travel move inside a part) will require to trigger it to get good results.

The length of the coasting could also be related to how much pressure is built up on the melt chamber according to volumetric flow and nozzle geometry, to get some sort of primitive nozzle pressure control. But I guess that that could be implemented later.

[fiveangle]

Also, Coasting would typically be mutually exclusive to having LIN_ADVANCE enabled with non-Zero K value as they work to do the same thing.

[ManuGithubSteam]

I seccond this! Coasting is a super feature in simplify!

[wfcook]

I have been hoping for Coast in Slic3r since I originally posted the request on the original slic3r issues board three and a half years ago.

It is a very simple feature, as it simply breaks the move into two parts and stops the extrusion for the last X distance in the move before retracting and lifting the extruder.

I realize that it isn't the most requested feature, but I think you'd find that it is (a) fairly easy to implement and (b) one of those features that people really do need even if they don't know that they need it. Its effects are almost magically positive.

The absence of this feature is the only reason I am still using Simplify3D. I simply cannot get the print quality out of Slic3r with a bowden extruder that I can with Simplify3D.

[tecnopolis-ve]

@Itox001

Basically, it stops extruding a certain distance before the current extrusion line ends, giving time to relieve the pressure in the melt zone and avoiding blobs, when filament flow is cut out.

Shall the coasting feature only be active just before a retract, or shall it be active for any stopping move?

Slic3r does a bit of "coasting" to hide a seam on any closed loop, but the coasting distance is fixed to 15% of a nozzle diameter.

for any retraction and should be configurable. if retraction is disabled this should be disabled too.

Thanks!

[dot-bob]

I have a couple of printers with a volcano hotend that would really benefit from this feature. I can't get the seam on my prints using the E3D volcano hotend with slic3r too look as nice with as S3D using coasting. This is even with S3D's inablitiy to properly hide seams.

[bubnikv]

@jindrichbenes How did we handle the high diameter nozzles in Slic3r PE?

[jindrichbenes]

@bubnikv we increased overall speed of 0.6mm nozzle to 110%, which was safe for the then 200mm/s infill, but it seems to be gone by now.
Roman Týr is looking into 0.6mm settings further.

[bubnikv]

@jindrichbenes How did you solve the gaps at the end of the perimeters? I
remember we had some significant gaps for 1mm and higher dmr nozzles.

On Mon, Mar 4, 2019 at 11:09 AM jindrichbenes [e-mail]
wrote:

@bubnikv https://github.com/bubnikv we increased overall speed of 0.6mm
nozzle to 110%, which was safe for the then 200mm/s infill, but it seems to
be gone by now.
Roman Týr is looking into 0.6mm settings further.

—
You are receiving this because you were mentioned.
Reply to this email directly, view it on GitHub
https://github.com/prusa3d/Slic3r/issues/246#issuecomment-469194846, or mute
the thread
https://github.com/notifications/unsubscribe-auth/AFj5I-cq9PWsVRyx34HGZV-JX5FuvA_Lks5vTPDlgaJpZM4M5Xn2
.

[jindrichbenes]

@bubnikv extra_lenght_on_restart and linear advance, for 1mm nozzle namely 0.5 extra lenght and 10 linear advance

[banzaito]

come on guys ... I've been waiting for it for a long time

[liftbag]

I usually print with filaments that don't require coasting, but others produce terrible seams with slic3rPE. It is the only case in which, through coast at end, I get better seams in S3D.

[DarkMonkChad]

Any chance there is an update on this? (also thank you for all of your hard work on this)

I am printing TPU and find that I could REALLY use coasting at the end of a perimeter before a retract. I am using a .8 nozzle and if it sits still at all you get ozze. I am retracting 5mm, which helps but introduces air in to the nozzle and I am getting a consistent bubble/pop a set distance after the next extrusion starts. I believe coasting would solve this but I use to use Simplfy3D a lot and am use to using it there. If there is another answer to this, please let me know. Thank you.

[Carib3D]

I'm trying PrusaSlicer after years of S3D and I'm so disappointed that there is no coasting option. For many prints, this is vital to minimise blobs and strings. I add my vote to those who have requested this feature.

[DarkAlchy]

I tried the Lin_Adv in Marlin 2.0 and while it was very nice it was not without flaws as it retracted, extruded, retracted, extruded like that every few steps so would wear out everything much faster AND it left some gaps in straight walls (yes, my K value was the best I could see) so I am going back to the old way but now I need coast at end again. I love the Prusa Slicer but in all of this time Slic3r has never had this feature added YET S3D, and now Cura, has it. I don't want to go back to S3D as I am an old user of Slic3r but the lack of a coast at end feature made me run off to Cura where I never was able to get it to 100% because it has a lot of hidden settings (according to the Cura people) that they refuse to let us have access to so I was never able to dial it in. My issue with Cura was infill was missing in the exact same spots and walls had gaps but in S3D and Slic3R/PE/Prusa Slicer the model was perfect.

I went off on a tangent there but I was trying to show just how valuable this feature is to me as it is so valuable that the lack of having it sent me off to find a replacement program. If these programs were paid a business would see what I did as a bad thing and as a potential in a loss in revenue and try to implement this much needed feature.

[tutulino]

PrusaSlicer is my favorite Slicer, but due to some features lack like coasting or ironing I get better printings with other slicers for not Prusa machines

[mister2212]

is there any news about coasting feature?

[jltx1]

don't these extruder features give the effect of a coast?

[guestisp]

No

[jltx1]

No

succinct and correct. I sliced with different settings and examined the g-code. This setting is not doing what I had expected, which was 50% coast 50% wipe. That is, I thought it started the retract before the end of the line. But in fact it completes the line, then retracts the partial amount you specify then completes the wipe with any remaining amount of retract.

So no coasting is available in PrusaSlicer as far as I can tell. I add my vote to include this feature.

[kevlarfab]

I definitely wish to have coasting enabled.

[anotherboringuser]

I am just another user who really wants this feature

[guestisp]

@jltx1 wipe and coasting are different. With wipe, you go back with the nozzle to clean it from any blobs. With coasting, the extruder will stop to extrude before the end of the perimeter/line because it would use the blob as "extrusion".

One goes back, the other moves forward.

[kookaburra88]

What wonders me with PrusaSlicer (and other slicers like Ideamaker) is, that start and end point of (outer wall) perimeters do have the same position in gcode. So basically at the very end of the perimeter the printer is forced to extruder material into a spot, where it already extruded material at the beginning of the perimeter. The material overlap (roughly) matches the linewidth, thus coasting matching the linewidth should fix this.

[jltx1]

@jltx1 wipe and coasting are different.

Yes, I am aware of the definition. I just thought those controls did something different than they actually do. There is only a wipe and no coasting.

I'm not sure what is the intent of the controls as implemented. Maybe they were trying to have a coast but it is broken. Because it is not an unreasonable way to implement it. You specify, separately, how much retraction you want to do given your printer/extruder. Then you specify when that retraction starts with respect to the end of the line. 100% before means coast, 100% after is wipe, in between is an overlap. So that's what I had interpreted, wrongly.

[madsi1m]

Coasting would fix my current problem.
Zooming in on the preview i can see a gap between start and end of a loop so it seems to do some hard coded coasting, we just need to make that value something we can configure

[gnydick]

@jltx1 100% retraction before wipe means no wipe happens at all.

[CraigFaz]

This is a feature i've been wanting for ages, its the one thing i really miss about using S3D.
I use the Volcano, on one of my MK3S, and this feature would really help with the z-seam.

[robschwieb]

Any chance this will make it into the next RC?