0.25 Nozzle Problems  

Re: 0.25 Nozzle Problems

Your bed seems to have a lot of marks on it. Have you tried dish soap? It will remove grease and oils much better.

Re: 0.25 Nozzle Problems

The adhesion of the metal plate is good its stiking properly to the bed it has to be something else.
what i noticed is, that when i turn on the fan in the first layre it gets a little bit better, for me it looks like it gets too hot and thats why this waves come out.
I dont know what to change for this

Re: 0.25 Nozzle Problems

Have you recalibrated your live-z? You may be too close to the bed.

Re: 0.25 Nozzle Problems

i calibrated the Z and fine tuned the Z.

The Problm only is, when the printer starts to Infill, when he is doing single lines or go around the line like 4 times, there is no problem this works perfect.

Re: 0.25 Nozzle Problems

If those pictures are of your 1st layer, you are way off on your Live-Z setting. You need to re-calibrate it for the new nozzle. Rather than trying to dive into a complex print, try replicating the "Life-Z" procedure. Create a 75x75x0.20mm flat square print 1 layer high using your material and nozzle parameters and print it with rectilinear infill. Until you get that to print and adhere properly, there is no point trying to print anything more complex.

I would recommend giving your bed a thorough cleaning and following the recommendations in the Prusa Material Guide for ABS.

Re: 0.25 Nozzle Problems

Create a 75x75x0.20mm flat square print 1 layer high using your material and nozzle parameters and print it with rectilinear infill.

For a 0.25mm nozzle, shouldn't a lower (thinner) layer height be used?
IIRC, the 0.20mm first layer height is used for a 0.40mm nozzle (a layer height of about half the nozzle diameter).
Extrapolating from that, wouldn't a 0.12mm to 0.13mm layer height be more appropriate for a 0.25mm nozzle, or is the "half the nozzle diameter" ratio coincidental? ❓

Re: 0.25 Nozzle Problems

[...] For a 0.25mm nozzle, shouldn't a lower (thinner) layer height be used?For upper limits on layer heights, the convention is up to 80% of nozzle diameter, lest you print cylinders which will have poor inter-layer adhesion. This gives you a maximum of 0.20mm for a 0.25mm nozzle. I've just been playing with a 0.20mm nozzle which required going to 0.16mm maximum layer heights.

The closest thing I've found to a convention for lower limits on layer heights is 25% of nozzle diameter. My understanding is that it's more a question of stepper motor resolution. I'm actually running some test prints trying 0.03 and 0.025 now. I got some interesting results using adaptive layer heights with a 0.60mm nozzle, so that 25% doesn't seem so well supported in practice.

I've worked up a spreadsheet cheat sheet for all this stuff. My brain dump on nozzle sizes is here if anybody's interested. I'm putting up some pre-generated STLs here , although I've only got 0.60mm prints now. The direction of the 75x75 square is backwards, so it's a bit more annoying to use than the "life adjust" prints, but better than nothing if you're using something other than a 0.40mm nozzle. I hope to re-generate them soon printing from lower-right to upper-left.

Re: 0.25 Nozzle Problems

Hi Rufus

General wisdom, advises that Layer height shoulldn't exceed 80% nozzle diameter,

80% 0f 0.25, is 0.20mm

I believe that the Prusa Mk3 is hardcoded to produce a minimum of 0.15mm first layer...

the finer the first layer the more difficult it is to get a good live Z adjustment...

regards Joan

Re: 0.25 Nozzle Problems

[...] I believe that the Prusa Mk3 is hardcoded to produce a minimum of 0.15mm first layer...
Interesting. I threw a 0.16mm layer at it using a 0.20mm nozzle without any problems, but I haven't tested to see what actually printed. Going lower should only be necessary with a 0.15mm nozzle which is definitely "experimental" on the E3D site.

At one point, I got a very thin 1st layer schmear using a 0.20mm nozzle that was very difficult to remove. Any idea if this is a new firmware feature?

Re: 0.25 Nozzle Problems

😕 ? So, are you guys saying my guesstimate of approximately (for some reason, this editor doesn't seem to like the tilda character... 🙁 ) half the nozzle diameter is dead wrong, OK, acceptable, or what? Of course there would be a range--I was just asking about a ballpark, OTTOMH median. 0.20mm just seemed (to me) a bit thick for a first layer with a 0.25mm nozzle--I wasn't sure you could get enough "squish".... 😕

Re: 0.25 Nozzle Problems

Keep layer heights at or under 80% of your nozzle height. With a 0.25mm, you can go up to 0. 20mm and have sufficient squish for good adhesion. Anything below that is fine down to 0.05mm and even below. My test at 0.025mm worked well today.

I've got tables on my notes page if you want a summary.

0.20mm seems to be a convention for 1st layer even with larger nozzles. It's thick enough to adhere well but you might want to use other setting for perimeters and such. "Thick enough but not too thick". A 0.80mm 1st layer with a 1.00mm nozzle would be interesting.

Re: 0.25 Nozzle Problems

😕 ? So, are you guys saying my guesstimate of approximately (for some reason, this editor doesn't seem to like the tilda character... 🙁 ) half the nozzle diameter is dead wrong, OK, acceptable, or what? Of course there would be a range--I was just asking about a ballpark, OTTOMH median. 0.20mm just seemed (to me) a bit thick for a first layer with a 0.25mm nozzle--I wasn't sure you could get enough "squish".... 😕

One reason for using a first layer of at least 0.2mm is that it makes the first layer much less sensitive to any imperfections in the flatness of your bed, and much less sensitive to inaccuracy in your live-Z adjustment.

Think of it this way: suppose you have your live-Z dialed in perfectly, but there's a bit of debris trapped under the plate that lifts one part of it by 0.1mm (about the thickness of a human hair). If your first layer is set to 0.2mm, that still leaves 0.1mm clearance under the nozzle and it should be fine if a little squished. But if your first layer is 0.15mm, that's only 0.05mm under the nozzle, which is really marginal. And if you were 0.05mm too low on your live-Z, then the nozzle is rubbing the build plate and your print fails.

Re: 0.25 Nozzle Problems

Keep layer heights at or under 80% of your nozzle height. With a 0.25mm, you can go up to 0. 20mm and have sufficient squish for good adhesion.

OK (also acknowledging Peter.I22's response).

(The smell of burning plastic is my brain thinking about this... 🙄 )

0.2mm layer height from a 0.25,, nozzle is not going to be as wide as 0.2mm layer height from a 0.4mm nozzle.
Does firmware/print settings adjust the distance between rows of filament laid down by these different nozzle sizes to ensure adhesion? Or how does that work?

Re: 0.25 Nozzle Problems

[...] 0.2mm layer height from a 0.25,, nozzle is not going to be as wide as 0.2mm layer height from a 0.4mm nozzle.
Does firmware/print settings adjust the distance between rows of filament laid down by these different nozzle sizes to ensure adhesion? Or how does that work?
Extrusion width is controlled by separate settings from Layer Height. They interact in terms of volumetric rates, but you can set them independently. The general guidance is to keep extrusion widths to 120% or less of the nozzle size. So far as minimal width, you're safe going down to the nozzle size. Some slicers can approximate smaller sizes, but that tends to be specific to the slicer.

In practice, it's your slicer that has to account for the extrusion widths. The gcode is not transportable if you switch nozzle sizes. You have to re-slice with the new parameters.

The best way to experiment with this is to fire up Slic3rPE, load up a model, slice and save it, then spend time in Preview mode. You can select the Height, Width, Speed and Volumetric flow rate view options to see the impacts of these different settings.

I've compiled a table of maximum and minimum layer heights based on nozzle size:

I want to stress that these are the "best practices" settings that are generally recommended. You can certainly stray outside these numbers, particularly on the lower end, but YMMV. More notes here.

Re: 0.25 Nozzle Problems

Extrusion width is controlled by separate settings from Layer Height.

Are you saying this is something I have to remember to adjust whenever changing nozzle size, or will the slicer program do this automatically with the change in nozzle size?

Re: 0.25 Nozzle Problems

Are you saying this is something I have to remember to adjust whenever changing nozzle size, or will the slicer program do this automatically with the change in nozzle size?
It depends on your slicer software and how you like to configure it. Using Slic3rPE, I have a set of Print Settings for each layer height I frequently use across all nozzle sizes. In each of those, I have Print Settings->Advanced->Extrusion width set to 0 for all items in the top block. Slic3rPE then calculates reasonable widths based on the current nozzle I have selected in Printer Settings. This works for most of my printing.

For detail work, I do have some "precision" Print Settings profiles in which I specify exact extrusion width. I use these for fine detail work like miniatures. For example, I have External perimeters set to exactly the nozzle diameter to get more precise external features, while setting First layer to 120% of the nozzle diameter for better adhesion.

I haven't done enough testing to say it makes a huge difference trying to be so precise. I'm happy with the prints I get with my "nozzle agnostic" print settings profiles.