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Very finest tuning?  

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Jimbo
(@jimbo-2)
Active Member
Very finest tuning?

I have a Mk3S+, running 3.12.2-5713. It runs well, I've live-adjusted the "Z" calibration and I get acceptable print quality (as long as I ensure I'm using VERY dry filament, this cold wet winter has made that a a major issue!). So far, so good...

But I want to get to the bleeding edge of print quality, I'm prepared to spend time and filament getting this *really* spot on, because I have a couple of things I want to print which are small, detailed and MUST be right...so what is the best process? The bed is absolutely flat and level, and is not moved, so thats not a variable, but I'm wondering if there are ways of getting the quality even sharper.

Do I factory reset and re-calibrate? I could do that but it would lose what is an acceptable starting point. I could go through the calibration serialy from start to finish but would that improve matters? I could jump into the calibration half way through, but would that be sufficient. Alternatively is there a way I could go that's a bit "off piste" but with effort gets me the ultimate print quality.

What have other users done that works, and is there a written guide apart from the official Prusa documents?

 

Thanks for all your comments

Jim

Posted : 17/04/2023 2:59 pm
jsw
 jsw
(@jsw)
Famed Member
RE:

If you don't think your Z calibration is optimal, there are a few things that you can do.

I think that the one item that is most overlooked is the left/right and front/rear adjustments.

You can get a good idea if you need to tweak these by printing one of those 3x3 9 square test prints (shown below), adjusting the live Z for the best 'squish' on the center square, and then comparing the center with the squares on the outside.  You can then dial in calibration factors to raise or lower the front/rear/left/right portions as needed.

I've found that for the textured build plate, the sweet spot for Z calibration is right at the point where the 'brush strokes' just disappear into the texture pattern.

You mentioned that you get good prints if your filament is VERY dry, which leads me to believe that you may have a chronic humidity issue.  You may want to consider a drybox to store filament spools when not being used.  I'm assuming that you have some kind of a device to dehydrate filaments.

Some people feel a need to tweak various parameters (bed/nozzle temp, print speed, whatever) to optimize prints.  I personally have rarely encountered a need to adjust anything.  Only one type of filament I use (Mika 3D metallic) needs a nozzle temp boost to avoid jamming.  I've found that on the Prusa, the best results are almost always using the defaults.

Of course the build plate needs to be spotlessly clean for proper adhesion.  I'm not going to admonish you to 'clean your plate and clean it my way', but we're adults and we know when something is or is not clean.  One stray fingerprint can cause a print to fail.

It seems like there are three factors, all inter-related, that are the most common causes of failed prints.  1. Dirty build plate.  2. Suboptimal Z calibration.  3. Damp filament.  It just seems like most of the reports of failed or poor prints come down to one of those three.

Posted : 17/04/2023 3:16 pm
fuchsr
(@fuchsr)
Famed Member
RE: Very finest tuning?

What jsw said. 

I would add,  get the temperature right for your filament and run a hollow cube to optimize its extrusion rate. 

Beyond that, I think things become more model dependent. You can go down plenty of rabbit holes "optimizing" retraction length, speed, etc. I found in most cases there's zero practical  difference in most general use  and not worth the effort  

But there are certainly model specific aspects that may warrant optimization. For example overhangs at the edge of being printable without supports may benefit from optimizing speed, fan speed, extrusion width, layer height in those areas. Height range modifiers and modifier meshes in Prusaslicer can help make those targeted adjustments. 

Otherwise I'm with jsw. "Optimize" when you see a need for it. Otherwise I'd leave good enough alone. 

Posted : 17/04/2023 3:40 pm
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