Default 0.25mm Nozzle Profile extrusion width is 0.25mm, is this an oversight?
From everywhere I've read you really want about 110%-120% of your nozzle's width as your extrusion width, so this is puzzling me that the Prusa profile for the MK3S /w a 0.25mm nozzle has extrusion widths all set to 0.25mm except for the first layer which is set to 0.3mm. I'd have figured it'd be more like at least 0.275 yah?
If this is actually an error this might explain some of my issues trying to master printing with that smaller nozzle, its one of the few settings I've never touched because I'd figured Prusa knows best, but figure its best to bring this up and get a second opinion. Small oversight?
RE: Default 0.25mm Nozzle Profile extrusion width is 0.25mm, is this an oversight?
Did you end up figuring this out? I've also noticed the discrepancy but I did not try printing with a 0.25mm nozzle yet.
RE: Default 0.25mm Nozzle Profile extrusion width is 0.25mm, is this an oversight?
The Prusa profiles stop at 0.15mm layer height for the 0.25mm nozzle, so using a 0.25mm default extrusion width is fine. General guidelines are to use layer heights up to 80% of your nozzle size and extrusion widths up to 120% of your nozzle width.
- With a 0.4mm nozzle, this gives you 0.48/0.32 or a 1.5 width-to-height ratio.
- With a 0.25mm nozzle, using a 0.25mm extrusion width with 0.15mm layer height (0.25/0.15) maintains a 1.67 width-to-height ratio, so you're still much wider than tall, which should maintain the desired oval/stadium extrusion cross-section necessary for good inter-layer adhesion. At a 0.2mm layer height, you're down to 1.25
I assume Prusa went with a low width in consideration of the fact that most people are after maximum detail with such nozzles. They appear to have limited presets to 0.15mm layer height accordingly. If you use wider extrusions with a 0.25mm nozzle, there's less of an improvement over a 0.4mm nozzle. You can get a 0.3 or 0.35mm nozzle if you really want to get into the weeds.
RE: Default 0.25mm Nozzle Profile extrusion width is 0.25mm, is this an oversight?
The Prusa profiles stop at 0.15mm layer height for the 0.25mm nozzle, so using a 0.25mm default extrusion width is fine. General guidelines are to use layer heights up to 80% of your nozzle size and extrusion widths up to 120% of your nozzle width.
- With a 0.4mm nozzle, this gives you 0.48/0.32 or a 1.5 width-to-height ratio.
- With a 0.25mm nozzle, using a 0.25mm extrusion width with 0.15mm layer height (0.25/0.15) maintains a 1.67 width-to-height ratio, so you're still much wider than tall, which should maintain the desired oval/stadium extrusion cross-section necessary for good inter-layer adhesion. At a 0.2mm layer height, you're down to 1.25
I assume Prusa went with a low width in consideration of the fact that most people are after maximum detail with such nozzles. They appear to have limited presets to 0.15mm layer height accordingly. If you use wider extrusions with a 0.25mm nozzle, there's less of an improvement over a 0.4mm nozzle. You can get a 0.3 or 0.35mm nozzle if you really want to get into the weeds.
Thank you Bobstro! Yes after posting that I continued reading about layer height vs nozzle extrusion width and realized that going 100% of the nozzle is acceptable.
As an update to my root reason for asking: I think my main issue was the prusament PLA filaments I have. Best I could get was about an hour and a half of printing before the extruder started jamming and I've been all over the map with various settings to improve that situation. I tried using Amzn's Clear PLA and got far far fewer jams as I dialed in an appropriate temperature but otherwise stock settings. At 205c it completed a 4 hour job without interruption, something I could not achieve with either black or orange PLA prusament I've got.
Since then I changed my game plan and ordered an Anycubic Mono X resin printer for my jobs that need this degree of detail and I'll continue using my Mk3s for regular 0.4mm printing needs, since its been operating perfectly with the standard nozzle.
So TL;DR: The biggest positive influence out of everything I've done to get consistent 0.25mm printing was using Amzn Clear PLA instead of the Prusament solid colour PLAs I have.