Max layer height and too high layer height  

Re: Max layer height and too high layer height

The general rule of thumb that I use (other people use different values) is that a layer 50% of the nozzle will print in "finished quality" (assuming that layer height cover's your feature shapes.) Thus for vertical wall boxes, 50% of nozzle is perfect.

For draft quality (fit checks, quick things that don't need clean surfaces, and larger things with limited details) I will print up layer heights up to 80% of the nozzle diameter. The surface is no longer flat, but layers are more visible, but that is okay.

Thus rafts where you don't care about the surface finish should be able to go even higher. I have not experimented. (Sorry, I know that was your actual question).

For very large objects, I have even used a 0.8mm nozzle to really increase speed - when surface finish was not important. Stringing increases, but the speed can be worth it.

Re: Max layer height and too high layer height

Interesting, if 50% is "finished quality", what will be Damaging for the nozzle and hotend ?
For example, when SImplify3D for 0.4mm nozzle creates first Raft layer at 0.5mm, is it just for better adhesion and no one cares how ugly it is since you throw Raft away anyway, or that is also damaging to some parts ?
So far my experience, that I don't want to repeat, show, that 2mm layer with 0.4mm nozzle lead to leakage from top of the hotend (between hotend and radiator).

Is there any other examples with too big layer heights with small nozzles ?

Re: Max layer height and too high layer height

The only reason the nozzle leaks is that is loose. It doesn't have anything to do with slicer settings

Re: Max layer height and too high layer height

The only reason the nozzle leaks is that is loose. It doesn't have anything to do with slicer settings

I agree with erick.v. Did you install the nozzle at 300C? Search the forum, there is a nice instructional video somewhere.

Re: Max layer height and too high layer height

at 280, higher I get thermal runaway error.
Just to confirm - leaking nozzle means plastic going out above heater element (in between heater and radiator) and not actually from the side of the nozzle ? Since in my case it is going out there.

Re: Max layer height and too high layer height

at 280, higher I get thermal runaway error.
Just to confirm - leaking nozzle means plastic going out above heater element (in between heater and radiator) and not actually from the side of the nozzle ? Since in my case it is going out there.

A picture is worth a thousand words...

Peter

Re: Max layer height and too high layer height

You can see relatively small blob on top of the heater block. It was much bigger initially (after that 2mm layer Raft), I did clean it twice and last few days I just printed somethings mall to not get huge overflow.

Re: Max layer height and too high layer height

That's a wrongly installed nozzle.

You need to remove the nozzle and then the heat sink and heat break from the heat block.

Clean the two mating surfaces of the nozzle and heat break.

Screw the nozzle into the heat block fully and then unscrew half a turn.

Screw the heat break (with heat sink) into the heat block and hand-tighten against the rear of the nozzle.

Heat up to 250 to 260 degrees and tighten the nozzle with spanners on bot nozzle and heat block.

Peter

Re: Max layer height and too high layer height

Interesting, I was printing fine before that Raft incident.

Anyway, time to do some high temperature mechanical work.

Re: Max layer height and too high layer height

When you dismantle the extruder, check the heat break, just in case it is bent slightly.

It may have a small crack just above the lower (small) threaded area.

Peter

Re: Max layer height and too high layer height

In the end everything was so in plastic, that easiest (and least messy) solution was to replace everything, since I could not even get heater cartridge or terminator out.

I replaced everything with E3D V6 12V Direct heater (with original tube, since it seems Prusa did cut it in an interesting way); however, I noticed, that I can't go above 277 degrees anymore and heating is little slower (I did change whole heating system including new cables to board, etc).

Double check nozzle and so far nothing leaking in the wrong places (tested with E3D FleXD and A910 Nylon, in hopes, that if something is wrong that will get out first in random places), so so far all good, tpu ... tpu ... tpu...

ON a side note I did manage to damage PEI sheet again in my favorite place (second point); however, that is easy fixable, just need to to find gloves that will not be eaten by chemicals I use to get off old PEI sheet. I always wonder, how first point work fine, but second point go crazy, and if I just run whole thing again, then all works perfectly.

This was an interesting adventure; however, I did not get definitive answer, if there is one - what layer height (probably in % to nozzle diameter) is fatal for the hotend ? Or that is all relative, meaning, for example, 2mm for 0.4mm nozzle with 40mm/s might be fatal, but with 5mm/s might be not, etc ?

Would be interesting to know limits with out self experiments 🙂

Re: Max layer height and too high layer height

E3D V6 has a maximum melt volume of just over 10mm^3/s. Or just over 4 linear mm of 1.75mm filament.

Your layer height range is about 20% to 75 or 80% of nozzle diameter.

And you probably now have a 30W heater from E3d rather than the 40W from PR. But that's not an issue; I refuse to go higher than 30W and it has never caused me any problems. You can always use a sock.

Peter

Re: Max layer height and too high layer height

Interesting, I did not notice, that heater that come with E3D V6 kit was 30W, while they sell 40W separately; however, I don't remember printing anything over 255C. So far only material I was not able to print is PMMA, and from temperatures it needed 120C Bed, but I am not sure that is related to warping, and other issues I have with PMMA.

As for Layer height, I fully understand that it must be below 100%, I am just wondering, why Simplify3D uses 0.5mm first Raft layer for 0.4mm nozzle (1mm for 0.8mm nozzle, etc) and They say it is normal and not damaging for everything, just looks ugly.

Re: Max layer height and too high layer height

That would be because its a raft...

Printing the raft at 0.5mm layer would present a smaller upper surface and it would break away more easily - which is exactly what you need a raft to do.

Peter

Re: Max layer height and too high layer height

Also, the thick raft layers put down by S3D are done much slower than what a usual first layer would be laid down so as not to over-tax the hotend.