Few Questions...

I have a few questions with slic3r. I'm using Pronterface + latest slic3r driving marlin firmware are on RAMPS1.2 board. Mendel (not prussa). Printing PLA through a 0.5mm nozzle.

First Question - I've got everything calibrated as per various sites... but slic3r seems to keep the filament too far apart, so top surfaces end up with spaces between the filaments. I can literally stick an exacto knife in between the filaments. OF course, this would make it pretty hard to print a water/air tight object. The only way to get it to look like it should (as I see other photos of prints) is to change the extrusion width value on the Advanced tab.... I have it up to 1.8 right now and the surface fills are perfect.... but now my inside/outside values are all messed up, i.e. a 20mm square will now no longer fit in a 20mm notch....Any suggestions?

Second Question - I read somewhere that your layer height should be an even multiple of your steps, to get even layer builds. I'm using 1/4 stepping on the z axis right now, and my scaling put me at 1655 steps/mm. I wanted roughly 0.3mm layer thickness, so doing some maths came up with 0.2996978852mm as my layer height (that times 1655 gives me a layer height of 496 steps). Is these worth it, as g-code is only to thee decimal points?

Third Question - I added some start code (pre-heat the xtruder, turn on my fan, and home all axis.) For some reason the X home motion is crazy slow... much slower than if I just send a G28 direct to the printer. I've attached the gcode to see if anyone can pick out he weirdness..

Thanks in advance!

-Rob A>

Edited 1 time(s). Last edit at 04/15/2012 10:21AM by RobA.

I think your problem is the layer thickness. When I had a 0.5mm nozzle and printed in PLA, I usually had layer thicknesses of around 0.30 to at most 0.40mm. You need to press the upper layer at least some into the one beneath it, and if you are using a layer thickness of 0.8mm then you are basically dropping it onto the layer below. That can lead to adhesion problems and is probably also the reason your horizontal threads don't touch.

Let Slic3r do the math for you. Set your extrusion width ratio back to 0 to let Slic3r figure it out for you, set your layer height to 0.35, and see how the box turns out. I think you'll like it better.

I had the same slow initial movement and got around it by adding as the last statement in my start gcode 'G1 X1 F9000' .

Thanks Mkouri - there was an error in my post.

I was printing at 0.3mm (not 0.8) but now have it set to 0.2996978852mm... Rest applies.

-Rob A>

I still think its the extrusion width ratio. I use values closer to 1.0 - 1.15 when printing in PLA, depending on the filament color and the temperature I am using. Hotter temps cause the filament to swell more, and more richly colored filament seems to need hotter temperatures to print well. With a value of 1.8 you are telling Slic3r that your PLA will end up almost twice as wide as it is tall without any compression due to lower layer height than the nozzle width.

Measure the extruded filament diameter after feeding some into free air. I bet the swelling will be a lot less than you think. One other point, I've found that over time my nozzles seem to close up somewhat so free air extruded filament is thinner than when I use a brand-new nozzle. I'm not sure if that's due to clogging over time or my use of pliers to clean the accumulated plastic residue from the surface of the nozzle.

The inside of the nozzle aperture can get coated with burnt plastic, see [hydraraptor.blogspot.co.uk]. I used to have to ream the hole regularly, but not recently. I think the plastic I get nowadays must be better.

---

[www.hydraraptor.blogspot.com]

Mkouri Wrote:
-------------------------------------------------------
> With a value of 1.8 you are telling
> Slic3r that your PLA will end up almost twice as
> wide as it is tall without any compression due to
> lower layer height than the nozzle width.
>

Really? I find if I leave it at 1.0, the filament of the surfaces of my prints is stringy - i.e. the filament strand is too narrow for the spacing between filament) The only way I can "fix" it is to dial this parameter to 1.8, and then it pushes out more PLA so the filament gets squished by the hot end into ovals, so the surface filaments all connect.

How can I get it to move the filaments closer together when at 100% otherwise?

-Rob A>

RobA Wrote:
-------------------------------------------------------

> Really? I find if I leave it at 1.0,

Auto is 0 not 1 so that could be your issue.

---

FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver