Witness lines in print, Prusa Slicer  

RE: Witness lines in print, Prusa Slicer

Bob,

I am working on a Github post... and will add a project to it... simply adding latest part ...

Here is a link to the stl..

https://www.dropbox.com/s/6mq9zfv2jzmjnjp/Vue-4body.stl?dl=0

RE: Witness lines in print, Prusa Slicer

Posted by: carter.m2

Here is a link to the stl..

It's a bit of a print, about 4 hours. I cut the part into roughly the bottom 1/3rd. Do you think this is a good representative part to show your problem?

I'll be printing it with the attached settings. I'm in the middle of an overnight print, so won't get to it for a bit. I'd be curious to see your results using these settings. We can compare results when I do get this done. Any particular filament or other settings to be concerned about?

Is this a housing for the new RPi 4B by any chance? Looks like 2 might fit.

RE: Witness lines in print, Prusa Slicer

Bob,

thanks for doing this...

i will print it with your settings... starting in an hour.

the problem is indicated in prusa slicer when it renders the tool path, you should see ghosting of the bosses.

i printed the whole thing again  earlier today with the same problems... 

i put the 3mf  file on github

printing in enclosure, warm weather, ABS

carter

RE: Witness lines in print, Prusa Slicer

Config file is for PLA, 4mm nozzle... I am going to change it to ABS, .6mm nozzle...

C

RE: Witness lines in print, Prusa Slicer

notice the image has ghosting of the bosses ... there are other bulges where the opening on the flat plane are... they are creating bulged layers all the way around the part at the beginning and end of the opening, no shown in Pslicer...

RE: Witness lines in print, Prusa Slicer

Posted by: carter.m2

Config file is for PLA, 4mm nozzle... I am going to change it to ABS, .6mm nozzle...

The extrusion widths in my profiles are set to 0 (auto) so that should work. I've included an updated config for Generic ABS & a 0.60mm nozzle just for consistency. I'll try printing with these parameters tomorrow. I don't have ABS, but this should give an idea of how significant slicer settings are. I'll print the bottom 1/3rd of the part for speed's sake.

config ABS 0.60mm nozzle.ini

RE: Witness lines in print, Prusa Slicer

So this is interesting. I sliced in PS and got similar results:

Then I opened the gcode in ideaMaker to analyze it and don't see the weird layers in the gcode:

And also uploaded it to gcode.ws and don't see those shifted layers:

So now I'm wondering if it's a display artifact in PrusaSlicer, or PS is showing us something about actual extrusions versus simple gcode moves that the others aren't... in which case it's more accurate from the display perspective, but the question of why those layers are weird remains.

Looking forward to printing this to see how it looks in real life.

RE: Witness lines in print, Prusa Slicer

Bob,

I just got done printing a third of the part.

This is the nicest, cleanest, best surface I have ever printed!  Please tell me what is in the config file.  I used your first file, command L, changed to my prusa .6 nozzle printer, selected prusa abs,  and set my layer height .35, first layer ht at .25, brim 8, perimeters 3,horizontal shells to 4,4, infill 25%, grid, and extrusion multiplier to .988, cooling on at layer 5.

What did you change?   Why isn't PSlicer sent out with these settings? (This has set me back many hours.). Thank you so much for helping.

BTW your images show the bosses as ovals, in fact they do print out as ovals, but I suspect I can fix it with a support that pops out.

I am running the whole part again tonight and will check in about it in 8 hours or so.

Carter

RE: Witness lines in print, Prusa Slicer

Posted by: carter.m2

[...] This is the nicest, cleanest, best surface I have ever printed!  Please tell me what is in the config file.  I used your first file, command L, changed to my prusa .6 nozzle printer, selected prusa abs,  and set my layer height .35, first layer ht at .25, brim 8, perimeters 3,horizontal shells to 4,4, infill 25%, grid, and extrusion multiplier to .988, cooling on at layer 5.

What did you change?   Why isn't PSlicer sent out with these settings? (This has set me back many hours.). Thank you so much for helping.

Glad to hear it helped! I have 2 sets of profiles: A "QUALITY" set (what I provided) and a "SPEED" set. The quality set is primarily different from Prusa's in using a 3rd external perimeter at very slow speed (25mm/s). I've found that this makes a huge difference on surface quality and is the biggest bit of magic in the settings. 

For printer settings:

• I've set retraction to 0.4 and Lift Z to 0.4. I've increased retraction speed, and de-retract to 25. I change these a lot, but these values seem to work with moderate stringing. YMMV. Go back to Prusa's 0.8mm retraction with 0.6mm z-lift if you aren't happy with stringing.

For print settings:

• Increased external perimeters to 3 at 25mm/s for surface quality. This fixes many of the surface issues.
• Slowed down perimeter speeds but increased some internal feature speeds. In my (admittedly limited) testing, hidden surfaces don't make nearly as much of a difference to appearance as external., so I cheat and speed internal extrusions up. This seems to keep print times reasonable with much improved quality. Play with these to see what works for you.
• Enabled the all of the quality settings for thickness. Many of these come into play with overhangs, so may not make a big difference in some prints.
• I've been working a lot with acceleration. 1500 for infill seems to work well. I keep it slow at 800 for perimeters. I've set the default to 4000, with the theory that fast acceleration is helpful for reducing stringing and quality matters little with non-printing features. Still under testing. This is what keeps the ringing better than Cura's default results I think.
• I've set max volumetric speed. I like setting this here for the hotend maximum. I go with 11.5mm^3/s which is down from the claimed 15mm^3/s for the E3D V6. This is definitely one you can play with and will (along with its twin under filament settings) make a big difference in your top speeds (MVS actually).

The only things I do in Filament Settings:

• Measure and average the filament diameter.
• Calibrate the extrusion multiplier.
• Set MVS. If I have time, I will calibrate this in the future. (PS will use the more restrictive of MVS settings at slice time.)
• Calibrate Linear Advance and temperature for each filament.

Note that the config I uploaded used Prusa's default ABS profile, so this filament settings didn't come into play.

Slicing your full part with the Prusa Quality profile, print time was 4h25m with a 0.40mm nozzle at 0.20mm layer heights printing PLA. With mine it's 4h37m, so very comparable over a longish print even printing a 3rd perimeter at slow speed. I think the other optimizations have evened things out. I'm still fighting fine stringing, but that's mostly an issue with stringing benchmarks, not actual prints.

Things are more interesting with the SPEED profiles. Mine shows a print time of 2h49m whereas Prusa's SPEED profile shows 3h32m. I've done a lot of tweaking of acceleration for speed. If time allows, I'll try your modified part with both QUALITY and SPEED profiles for comparison.

BTW your images show the bosses as ovals, in fact they do print out as ovals, but I suspect I can fix it with a support that pops out.

You'll usually see a bit of blue on top of those tops indicating unsupported features. They tend to print as a straight line across the top, making that oval shape. If fit matters, I print holes a little small and enlarge the opening to the right size. Support helps a bit, but may still result in distorted openings. (And of course, my images are distorted by the forum software. Grr.)

I am running the whole part again tonight and will check in about it in 8 hours or so.

Very curious to see your results! My overnight is still going so it'll be tomorrow before I can test.

As to why Prusa chose the defaults they did, hard to say for sure. I suspect they've gone for a general case, balancing fine prints for miniatures versus speed for big functional parts. It's impossible to make everybody happy, so they've gone full corporate and made everybody unhappy. A perfect balance! I'm not about to second-guess Jo & his team, so I'll just say my profiles work for me and YMMV. They're smart folks, so I'm sure there are reasons they wound up where they did. They do seem to tweak them a lot. (Hmm. MMU support may be a big part of their decision process.)

I definitely recommend spending time understanding as many of the settings as you can so you can do some testing to see what makes the biggest difference in your prints. Once I find settings I like in Prusa, it's relatively easy to transfer those over to Cura, Simplify3D or any other slicer. I think of PrusaSlicer as my Engineer's slicer, all about repeatability, so focus on it 1st. It is very finely tuned to the Prusa printer capabilities. I'm dumping everything I know about PS, the i3 Mk3 and 3D printing on my notes pages, so feel free to look around for info. I eventually hope to explain everything. I do need to update the set of profiles there, but it's reasonably current.

RE: Witness lines in print, Prusa Slicer

Bob,

Excellent!  I am so glad I got your help.  Take a look at the image attached.  It is an excellent print and you've introduced me to a ton of information.  I will read your notes page... 

Please try out the parts I made to strengthen the framing and other improvements, I think that they help improve part quality.

https://www.prusaprinters.org/social/6839/prints

In particular the power supply brace and the YZ case.

Thanks very much,

Carter

RE: Witness lines in print, Prusa Slicer

Posted by: carter.m2

Bob,

Excellent!  I am so glad I got your help.  

Happy to help. We've got a great community here (despite the new software) and I've learned a lot.

Take a look at the image attached.  It is an excellent print and you've introduced me to a ton of information.

Looks good... but tiny. Can you try with a larger image size. (I find hosting pics offsite in imgur yields much better results).

 I will read your notes page... 

Please try out the parts I made to strengthen the framing and other improvements, I think that they help improve part quality.

It's on my list! Still cranking out drawer dividers for my new office layout. I've been churning at 0.64mm layer heights with a 0.80mm nozzle for 2 days now.

https://www.prusaprinters.org/social/6839/prints

In particular the power supply brace and the YZ case.

Yowza. Very nice pieces! Just so happens I moved to Octopi from a failed Toshiba FlashAir as part of my office re-org, so those RPi cases are perfect. Looking through your collection now. Great stuff, and thanks for contributing!