Smallest layer height capable

[BlueDust]

I know I know... lots of things should affect this, not just the Duet2.
But in conversation, I asked people who know more than me about 3d printing about experience with exotic filaments like copper, bronze, carbon fiber... I asked what is the smallest layer height that could be effectively printed. At the time I have never tried anything smaller than .15, and was thinking that FDM would have its limits with metal power and either wouldn't come out smooth enough at small layers to lay down, or when end up scrapping the print after a few layers (or something). I was asked to try .06 layer height. That's much smaller than would expect with filament that has solids mixed in. Also I wondered why .06. Why not .05, or .08....
So now, I am wondering, what is the Duet2 capable of doing. What is the smallest layer height the Duet2 can print? My question is not specific to my printer, just specifically about the Duet2 itself.

But... If you want make my question personal.

I am using all e3d banded steppers with .9/Step.
This may strange, but I am only using microstepping on my extruder...
M350 X256 Y256 Z256 I0
M350 E16 I1
My steps per mm... My Z screw has 4 threads (1mm pitch 1:4 ratio)
M92 X2560 Y2560 Z12800 E825.598

Let me know if you need any more info and want to make it personal. If you know how to figure this out, please share the math with me.

At the moment I am printing a D&D character in Bronze set at .06 layer height in S3d. If I looks at the layers for this print of 1012 (via S3d preview), and see that S3d tells me the model is 73.07 mm tall. Duet tells me the same model is 60.71mm tall. (Weird I know)
Doing some math...
S3d says its actually making the gcode file to print at .0722035 mm layers
Duet2 says the layer height is .0599901 mm

I will share a picture if this fails or succeeds.

Thanks!

[NitroFreak]

the lowest reliable layer height would be 1 fullstep. so 1/400ths of a rotation of your stepper * 4mm/rev = 0.01mm.
I would not go lower than one full step because in intermittent positions the stepper can snap to a full step position, messing up your layer height.

[BlueDust]

Thanks!

So the print failed because of some weird good that came out of the nozzle halfway through the print. It could be a mixture of previous Filaments but I have no idea. I generally run a 100mm + through the nozzle to clear out any previous Filaments and Bronze should have shredded through anything in there long before it clogged. So... Wonder if there was a good amount of filament that didn't mix in with the Bronze on the spool and just clogged the nozzle when it melted at a different rate then the bronze filament. I am leaning towards previous stuff but there is a lot. I was by hand trying to drill it out of the nozzle and have more cleaning to do to make it usable again. I attached a few pictures. You can see a few drops of the clogged stuff I pulled off the print. But there was a lot more I lost when taking the print off the bed.

[JoergS5]

@bluedust Nice object which you try to print! First you can set layer very low by using a gear between stepper and z axis. If you use a harmonic drive with 1:160 and a low spindle height of 1 mm per rotation, a 400 step stepper, then 0,015 micrometer per step. But it will take forever to print...

The funny layer heights in your discussions come from spindles TR8x1.5 or TR8x2 (1.5 or 2 mm height per rotation) multiplied with the stepper properties, or if belts are used, 16 or 20 teeth pulleys with GT2 2 mm belts and stepper properties. The result are typical layer heights by multiplying those properties: a TR8x1.5 has 3.75 micrometer for every step. Not every layer height is possible by multiplying this 3.75 with an even number. 0.15 mm layer height is possible with 40 steps for every Z movement, but not 0.2 mm.

Your print still has visible steps at the base, so I would take a different approach:
Personally I would print with a normal layer height and then sandblast the model to remove the layer steps. Stratasys recommends PMB http://articles.stratasys.com/en/articles/1924064-bead-blasting but I would try blasting with the material which you used to print, milled. The same material to avoid changing the colour.

[BlueDust]

@joergs5
Thanks for the info.
I am just trying to print this as a test. It seems to be about an 8 hour print, but will know for sure if/after I can print it successfully. I was just not confident I could actually print metal or any other filament that has solid power in it at such a small layer height. Yes, I am surprised by the easily visible layers at the base. At that layer height I expected it to be harder to see. I am really not sure what to make of it. But if I can print at .01 layers with my current setup, I may try to do that later if I can get a reasonable print at .06. Just because I can. I have other things I need to print first, before I can waste that time on a test print using expensive bronze filament (it's just a really small amount of filament). I also have copper and steel I bought to play around with. The steel brand is cheaper, but I think it's not as high a % of steel powder... I am thinking about make a chess set for a relative for Christmas. So playing around to see what I can get out of this filament. I plan on printing it at .1 mm layer height. If I can find another role of the steel at a good price, I may print the set using it, as I want to print the 2nd half in wood. They would have the biggest contrast (light/dark colors). But haven't decided anything yet as I still haven't found a chess set that yells print me!
So for now, just testing the extremes of the printer and filament....

[JoergS5]

@bluedust For the base the other thread https://forum.duet3d.com/topic/11707/non-planar-layers/22 would be ideal to avoid the layer steps, maybe you can use it.

Maybe you can show us your chess figures after christmas, your first tries look promising!

[BlueDust]

@joergs5
Thats funny you bring that up. I was just looking at that. I have never used Slic3r and was just thinking how hard it would be to get everything calibrated like I have in S3d... If S3d doesn't add new features I have been reading other slicers have been working on soon I may have to jump to a more up to date slicer.

[BlueDust]

From the left...
Acrylic, wood, pla, copper, steel, clay, pro pla, nylon, tpe, graphene, and pet (recycled pop bottles).
Just playing around with different filaments to understand how they print. Almost all of them were purposely printed with the same gcode made for the Blue PLA as a base. Manually upped or lowered temp or turn up or off fan to get them to print. Quality wasn't a concern. Comparing filaments was the goal. But some still turned out better then expected.

[JoergS5]

@bluedust Really nice!!

[BlueDust]

Used a spare nozzle to continue printing right away... 6 hrs 49 min. A bit more clean up then I expected. Still need to print the hands and weapons but it didn't come out too bad.

[bot]

Stepper motor resolution is only a tiny part in the puzzle of achieving small layer heights. I have successfully printed 25 micron layers, but with a caveat: segment length.

When printing such small layers, the detail of the model produces miniscule segment lengths. At this point, extruder resolution becomes more important than Z stepper resolution.

Also, more important than Z stepper resolution is the accuracy capabilities of the linear motion system of the Z axis. Straightness, orthogonality, and accuracy of the linear motion are all much more important than the Z stepper resolution. I use a ballscrew that is C5 rated, which more or less means it is "guaranteed" to be within 27 microns of its nominal position ( see here ), and my particular screw has a rated maximum backlash of 5 microns.

Add all these elements and more together to get the answer to how to print small layers well.

[fcwilt]

@bot said in Smallest layer height capable:
I use a ballscrew that is C5 rated, which more or less means it is "guaranteed" to be within 27 microns of its nominal position and my particular screw has a rated maximum backlash of 5 microns.

Could you provide a link to the product you are using and where you got them?

Thanks.

Frederick

[bot]

@fcwilt I'm using a Misumi BSS series ball screw. Don't look up the price if you're not sitting down...

[fcwilt]

@bot said in Smallest layer height capable:

@fcwilt I'm using a Misumi BSS series ball screw. Don't look up the price if you're not sitting down...

Hardware costs don't phase me much - like inkjet printers, filaments costs are going to be the majority of my expenses, in the long run.

Do you have a good source for that brand?

Thanks.

Frederick

[BlueDust]

@bot said in Smallest layer height capable:

Misumi BSS series ball screw

I just want to stand up and and look for prices... lol

I found one price using Google to search stores... but those prices can be misleading. Still a lot, but guaranteed! If you asked me what screws I have. I would say "yes".

My original question really is about what the Duet 2 is capable of printing. Next, (not printer related) what is the smallest printing height you should expect getting good prints from when printing with filaments with solids of some kind in them? The picture I shared above its better than I expected to get using .06mm using 70% Bronze PLA. But you can still obviously see the layers on the base of the model (not complaining, just surprised it was still fairly obvious).

[BlueDust]

Just something to look at. Model on left .06 mm layer height in bronze. Same one in post above. Model on right is pla and was printed at .1 mm layer height.

[bot]

@fcwilt

Misumi is the place to buy it. I believe it’s actually a different brand that they carry.

Misumi has branches all over the world. Find the nearest branch and search their website for BSS.

[JoergS5]

@bot an alternative to ball screws could be to build the Z axis with Piezo technology like the company Pi does it: https://www.pi-usa.us/en/tech-blog/piezo-flexure-actuators-nanopositioners-and-other-piezo-mechanisms-for-precision-motion-control-applications
But the movements are small, for the complete movement one needs something to "lift" the piezo. And there are new problems like hysteresis effects of the Piezo. This is a nice intro: https://www.piezosystem.com/piezopedia/piezotheory/