A method for less visible seams

[MichaelJLew]

The problem presented by the seams at layer change needs little introduction. It is sometimes trivial and sometimes important and PrusaSlicer offers a lot of variables that can alter the seam location, form, and visibility on the model. However, there is often no good way to prevent the seam from being #intrusive.

I have a method for making seams in my 'hand-made' gcode that are far less intrusive than those that I can achieve using PrusaSlicer. I believe that the method would be readily incorporated into the slicer and should be offered as an option.

I call the improved seam a 'scarf seam' because it is similar to a scarf joint that woodworkers might use to join two pieces of timber end to end. The scarf joint is conceptually simple as it simply has matching tapers on the ends of the timber that are glued together. A long taper gives a strong joint.

The standard seam can be described like this: the nozzle is positioned at the start of a perimeter at the z-height that is a full layer height above the previous layer. Extrusion starts and the nozzle moves around the perimeter until it arrives back at the start position whereupon the nozzle movement and extrusion stops. The scarf seam differs in that the nozzle starts at the same z-height as the previous layer. The Z-height is gradually increased as the perimeter is printed until it reaches the full layer height. (That is one of the scarf tapers.) The perimeter is then printed normally until the nozzle reaches back to the starting XY location, whereupon the nozzle retraces the first taper with a complementary taper where the layer height is decreased gradually to zero but the z-height is fixed. (That makes the second taper.) After the second taper is complete the nozzle can be moved away to complete the rest of the layer in the normal manner.

The low visibility of the scarf seam comes from the fact that the discontinuity of the joint if spread over the gradual tapers. When the nozzle is moved to the outer perimeter to start a scarf seam it is moved with effectively zero layer height and so there is almost no artefact from that movement. The scarf seam is compatible with any object shape, but I used a cylinder for the example for my own convenience. (I normally print fountain pen parts and most of my printing is pseudo-cylindrical objects with gcode from custom-written software and so I have a big library of cylinder-related functions.)

The scarf seam has a couple of possible disadvantages. First, it gives a region of variable layer height that may sometimes be visible. Second, it will be slower than the normal seam because it involves the nozzle moving twice over a part of the outer perimeter. That speed difference may be trivial in many cases as the scarf distance can be small compared to the perimeter total, and the outer perimeter is a small part of most printed objects. Finally, the scarf seam requires that the outer perimeter be printed first so that the first taper does not foul adjacent extrusions.

Example file

The attached file was generated by PrusaSlicer and then gcode generated by custom software appended. The PrusaSlicer settings were for the MK4 (no IS) and used the 0.20 QUALITY setting for Prusament PLA with the following changes from the defaults: no retract on layer change; no wipe; external perimeters first. The seam was painted on to force it to align with the seams from my software.

The first 6mm of the cylinder are the PrusaSlicer output. The region between 6mm and 12mm has a scarf seam with the tapers extending around the full 360 degrees of circumference. Between 12mm and 18mm the scarf seam has aligned tapers over 80 degrees of circumference. The alignment requires a retrograde travel move after each layer. The last section, 18mm to 24mm, has the 80 degree scarf but does not re-align the seams and so the seam moves by 80 degrees at each layer change.

cylinder d=12 h=6 v2d.gcode.zip

[MichaelJLew]

has gone unnoticed

Well, it was noticed by OrcaSlicer, as it has been implemented in 2.0 and 2.1. I was surprised by the lack of response from the PrusaSlicer developers, but it no longer matters to me.

[Androxilogin]

has gone unnoticed

Well, it was noticed by OrcaSlicer, as it has been implemented in 2.0 and 2.1. I was surprised by the lack of response from the PrusaSlicer developers, but it no longer matters to me.

I just installed Orca to try this. What is it listed as? I'm also wondering if the Kobra 2 profile would have the same settings as the Kobra 2 Pro.. There was no option for it.

[MichaelJLew]

Scarf joint seam in the seam portion of the strength tab. Try it with the inner/outer/inner option for wall printing order if you have three or more perimeters.

[Androxilogin]

Thanks, I'll give it a shot.

[mrflib]

It's odd, I found some old rollers I printed years ago. They are 25cm long and 4cm in diameter and printed vertically. There is almost no seam joint at all.. the print is nearly flawless.

This would have been printed on a MK3 using prusaslicer.

I wonder why things have got worse

On Thu, 4 Jul 2024, 03:43 Androxilogin, @.***> wrote:

Thanks, I'll give it a shot.

— Reply to this email directly, view it on GitHub https://github.com/prusa3d/PrusaSlicer/issues/11621#issuecomment-2207905629, or unsubscribe https://github.com/notifications/unsubscribe-auth/AIPJKO6WWPOQCGV76YTH2ODZKSZFBAVCNFSM6AAAAAA7DV6GVSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDEMBXHEYDKNRSHE . You are receiving this because you commented.Message ID: @.***>

[Harvie]

I wonder why things have got worse

what was the layer height?

[mrflib]

0.2 is all I did back then would have been completely stock prusa settings. Fillamentum petg

On Thu, 4 Jul 2024, 10:32 Tomas Mudrunka, @.***> wrote:

I wonder why things have got worse

what was the layer height?

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[sirguigui]

This seems very interesting, is there any way to currently use this in PrusaSlicer with an external post processing code?

I am hoping that since this is already implemented in Orca, that the developers will also seriously consider it for PS.

[klucky]

Such a great idea. I can't understand why it hasn't been implemented by the prusa team.

[MrDixioner]

Well, it was noticed by OrcaSlicer, as it has been implemented in 2.0 and 2.1. I was surprised by the lack of response from the PrusaSlicer developers, but it no longer matters to me.

You did a lot of work on this proposal: you described how it should work, you provided images and a file for the slicer, you provided the code that implements this function, but you only received complete ignorance from the developers :( I fully support your suggestion and I would give it a thousand likes if it were possible! I would like to know the reason for the complete lack of a solution to this problem on the part of the developers and hear their answer.

[amatulic]

I would like to know the reason for the complete lack of a solution to this problem on the part of the developers and hear their answer.

I think it's because the developers are (a) short-staffed, and (b) busy working on bigger changes and shiny new features, rather than algorithmic improvements to existing features, like the method described in this ticket. There's more to a fix than simply making sure it compiles without error and works; a huge matrix of use cases must also be tested, and this takes a lot of time.

I actually submitted a trivially simple PR (#9737) well over a year ago that fixed a bug in how temperature is controlled when switching between materials with the MMU, and while it got a lot of likes and positive comments like this issue, and Prusa staff were pinged multiple times, it never got a response, so it's still there. I and many others are using this fix, but we all have to compile PrusaSlicer ourselves to do so.

[RubenatorX]

Ya'll need to calm down with the rage comments. They are aware of the feature: https://www.reddit.com/r/prusa3d/comments/1bjqeb1/comment/kvvhgyn/?context=1

[mix579]

They know about it but it's probably not on the top of their priority list. Importance is in the eye of the beholder. I for one would rather have a supported method for drawing straight lines for seams and supports that has been requested for years. But they work down their own list of priorities, and if that doesn't match mine or yours, we can always use other slicers, I guess

[bkerler]

I really would like to see this as well and I'm confident they are already working on this :)

[ShakieVan]

This feature will be the best ever and would allow us to print better functional parts with narrow widths that won't glue together. I give a f. on cosmetic changes to the software. They don't make the print any better for me. I didn't buy a original Prusa printer to have fancy buttons in the Slicer.

[ZoomDomain]

66 comments. my 1 kilo robot planetary gear was kinda ruined by seams. I have to change to orca slicer to attempt it again. thanks!