.26mm vs .2mm layer height with .4mm nozzle

I’ve seen where Ryan has used a .26mm layer height. I’m assuming this is with a .4mm nozzle.
First, I’d like to know if there was some calculation used to arrive at .26mm, meaning why not .28mm or .24mm? How does this relate to layer width?

I’d like to discuss the theory and the pros and cons of this because wasting time producing unnecessary detail is something I’d like to avoid.

30% faster print time
Fewer layers = less opportunity for layer separation.
Better bed adhesion? Larger layer height better compensates for bed warp/leveling issues

Increased visibility of layers???
Decreased resolution??? (best to get a smaller nozzle)

I have read about some folks using .5mm and .6mm nozzles. Would we use the same idea there? (half the nozzle diameter*1.3) So a .5mm nozzle would have a .33mm layer height and a .6mm nozzle would have a .4mm layer height?

I print a wide range of things with respect to resolution requirements. Some intricate jewelry I’ve done required a lot of tricks in the slicer to print with a .4mm nozzle. A .25mm nozzle would have been better. And some big things (like MPCNC parts) would have been fine if printed with a .6mm instead of a .4mm

Okay this thread has the potential to get ugly. There are going to be opinions and facts, when they get mixed it can get heated.

I choose the nozzle size based on feature size, small features or holes = small nozzle. I don’t bother with anything less than a .4mm or larger than a .5mm. With that said larger nozzles are amazing for larger prints. I have not had the opportunity to print something that big, yet. So a 4mm horizontal hole with a .5mm nozzle and a .32mm layer height is too chunky for my taste.

My opinion is there is a sweet spot between layer height/width. I am sure this is a fact but can’t find a good link to share. For example a .4mm nozzle for me does very well between .2mm-.3mm height. Right in the middle seems to always print very well for me. There is a hard rule of no more than 80% ratio, so for a .4mm, .32mm should be the max (very low.

The other major fact is overhang, there are facts about this. Steeper overhang angles need lower width to height ratios. My parts have a 45-50 degree overhangs usually 50 or less.

So to sum up my opinion, I chose the settings I do because all my parts have holes and overhangs. With the ratio I specified I get extremely consistent holes and overhangs with my printers.

This didn’t even touch on print speed as I am usually a little more concerned with quality vs quantity. Have printed mpcnc parts with a .5mm nozzle because the print time savings was awesome but I wasn’t very pleased with the results so went back to .4mm.

That 80% rule is something I’ve never heard before but my experience seems to agree. Printing at a .35mm layer height with a .4mm nozzle has never yielded acceptable results FOR ME.

So is there a rule for the other direction? Should we not print with layer heights below X% of nozzle diameter? I have not been especially happy with prints at a .15mm layer height either with my .4mm nozzle.

I’ve been very impressed with how different views are expressed on this forum. Folks seem to be respectful and ready to absorb whatever they can glean from any perspective.

I just tried to find some visual aids. There used to be so many it made the concepts very easy to understand.

I’ll keep looking, it would be good to link here. There are a few things speed vs layer bond strength, layer height (bond strength/resolution), overhang angle (layer height extrusion width), flow rate vs width.

The problems start to happen when advanced topics are brought up, you can vary layer height/speed/infill density during your prints. I leave those alone because it is relatively complicated, and you really need to understand why you are doing it first before you do it.