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I have the Rostock V2 and using MatterControl software and slicer. Im having an issue getting my wall thickness down to .5mm. I can't go below 1mm wall thickness. Ive set the perimeter to 1 and tested, changed to .5mm and also .55mm and tested. Im using a .5mm nozzle, so I changed the nozzle size to .49 in the software, since I read MatterControl wont print wall thickness at or below the nozzle and still no change.

What am I missing here? thanks!

You are referring to wall thickness, not layer height? I don't believe it can happen with a .5 mm tip. The opening on my tube of toothpaste is 8mm, What you're describing would be the equivalent of writing a letter with it, expecting the results to look like it was done with an ultra fine Sharpie, (.8 mm tip)

There's gotta be a way to make a single pass wall, right? Im getting 2 passes on my vertical walls every time, even if I set the perimeter to 1 pass.

The Nozzle is a .5mm, and youre saying I can't get under 1mm wall thickness with it? Your toothpaste analogy isnt what Im describing. I'm saying that if I change the wall thickness to anything under 1mm and/or perimeter number to 1 from 2 that its usually set at, I never get a wall thickness under 1mm. Something is preventing MatterControl from going below that number.

edit: I know the Rostock with the .5mm nozzle can make single pass .5mm walls, because my support material is that thickness when I build something with an overhang.

Here's what you posted: "I have the Rostock V2 and using MatterControl software and slicer. Im having an issue getting my wall thickness down to .05mm." I read that as you stating you are trying to print a wall with a thickness less than a sheet of paper.

If Mattercontrol can't give you a single pass, then try another slicing program. I gave up on Mattercontrol, and use Smplify 3d. I also got good results with Repetier, and using Slic3d for the slicer.

typo. fixed.

Ok, so Mattercontrol won't go below 1mm walls and below 2 passes?

I'm going to guess you modeled something with a 0.5mm wall and the sliver is doubling up on it.
Depending on what you are trying to print, if you just want a thin wall the best way to do that is create a solid object and set the infill to 0 and the perimeters to 1.
Thin features are handled differently by the various slicers, if it's a thin feature on on part of the model then you'll have to experiment to get what you want, try slightly undersized dimensions on the model, and see what other slicers give you.

Yes!

Here's what Im trying to print:
http://www.thingiverse.com/thing:1532755

Ive been setting my infill to 1, I guess next I'll try 0 and see what happens.

S3D, .5 nozzle, with layer width set to .45, PLA, layer depth .075

I'm sorry as I assume you can tell, I'm a total newbie at this. What should I do with that file you posted? I'm printing in ABS if that helps.

Also, I set the infill to zero with no change.

He has provided you a modified version of the camera mount you want to print for you to try.

I only have ABS. Can I change the values of what he sent to ABS?

Sure
try the MC numbers that the instructions give for the fan shrouds in the use manual.

Here's one for ABS, I increased the temperature, and added a brim to help keep it attached. I also increased the width to .49 mm.