"Coast" To Reduce Stringing?

[inventabuild]

KISSlicer has a lot of one ups on the other slicers out there, but one I noticed on Simplify3D called "Coast at End" looks interesting. It turns off the extruder a short (user defined) distance before the end of a loop. It can be used in conjunction w/ wipe to help minimize stringing.

Has anyone tried Coast at End?

[PenskeGuy]

Isn't that what Wipe does, except that Wipe happens after the layer is complete, instead of as it is coming to completion?

[Mikk36]

Isn't that what Wipe does, except that Wipe happens after the layer is complete, instead of as it is coming to completion?

No, wipe happens after a retraction, coast (in S3D) stops extruding (spinning the extruder stepper) before the end of the extrusion line to extrude off of just the backpressure in the nozzle/bowden tube (if present) before retraction.

[PenskeGuy]

I think that's what I said.

[Davide Ardizzoia]

PenskeGuy is right - KS does "coast to end" and it's called WIPE: you can decide the "coast to end" distance (and it's called WIPE) just in the MATERIAL section, appropriately.

Moral: be sure to dig deeper into KS, as many tools are there, perhaps just not well documented (apologies) but they do work.

Best Regards
Davide Ardizzoia

[PenskeGuy]

I think we're getting into a bit of misunderstanding. Whether or not Wipe happens before or after retraction, it happens after layer completion. At any rate, Wipe will reduce stringing. It just does it at a different time from Coast.

That said, I have requested something along these lines a few times; but not to reduce stringing. It is to further enhance the Seam Hiding by effectively slowing the flow rate at the end of the layer. Gap attempts to do this but it does just what it says; stops the head short of the end of the layer, relying upon ooze to fill the Gap then retract and jump.

The original suggestion was to have an adjustable ramp up/down on the flow rate at the start/end of a layer, respectively. IOW, the extruder speed would be more of a sine curve when it started and stopped.

What's a bit odd is that if you have 1 Loop and Wipe is on, Wipe happens after the end of the first layer and the next layer backs up to the seam and then goes over it. Probably not desired in that instance.

[626Pilot]

I don't see Wipe being as useful as Coast.

KISSlicer's behavior at the end of a path is to stop motion, THEN retract (during which time the filament oozes because you can never retract faster than it oozes), THEN wipe. This doesn't matter much if you're printing in ABS, but for PLA it's not a good behavior at all. I always get stringing and blobbing artifacts. Slowing the outer loop speed down to 10mm/sec helps, as does changing the prime/suck speed to 15-25 mm/sec, but with this behavior - stopping and giving the filament time to ooze before wiping - is not helpful at all. The result is tiny spiderwebs and little blobs of filament clinging to the side of the object. It's ugly, and I honestly can't see charging money for a piece with such artifacts.

It would be better if it coasted and then did a wipe, or maybe just coasted. Having the option to use coast, wipe, or both, would be ideal.

[octocpp]

I agree, I have personally requested this feature many times in various places. That is, to start retract before getting to the end of the path for two reasons. One reason is to minimize oozing, and the other is to not have a delay at the end of every pass that is going to retract/wipe. By the time it gets to the end of the wipe, the retraction is finished and the printer can rapid to the next location without a delay. it should be as simple as starting the retract at the same time as the wipe pass begins right?

[lonesock]

Hello! This is in the top-10 on my ToDo list. I'm in feature freeze right now to actually get the 1.5 release out the door (so the 1.5 will look mostly like the betas you've been using but with some internal bug fixes and a few small features). So coast will go in the 2.0 branch.

It probably won't be a traditional coast. When you stop driving the extruder the plastic oozes out to relieve the back-pressure, and as it oozes the pressure drops. So it should follow a roughly exponential decay. I plan to match that with the head velocity (to a point) then the optional retract & wipe. The curve will be a function of a bunch of things (material, distance from extruder to nozzle, temperature, nozzle diameter, etc). The builtin model will be fairly simple, but I am considering adding a plugin architecture to let you printer-geniuses have the most advanced control over extrusion.

Jonathan

P.S. It is extremely nice to come back to KISSlicer development! I missed it, and you guys!!

[inventabuild]

Welcome back Jonathan (to your forum)! It's great to see you back again!!!