Gaps in wall issues with .3 mm nozzle

I am new to the forum; just found this and was happy to find so many people.

I have a printer with a .3mm nozzle and printing a wall that is 1.2mm wide, when it print it uses three passes and leaves a .15mm gap essentialy between the passes. If it made 4 passes it would end up perfect at 1.2mm, is there a way to force this to happen. I have tried checking the box for thin walls and that didn't change it. I have tried the 1.1.7 code and 1.2.

I saw another post about changing nozzle size in the software, and wonder if that may work, but would like to see if there an approach that everyone uses and I am just missing it.

Edited 1 time(s). Last edit at 08/13/2014 01:55PM by AquaticsLive.

It sounds like you are under-extruding. This can be adjusted with the "Extrusion multiplier" variable found under "Filament Settings" of Slic3r.

Look in the G code file with a text editor and within the first few lines you will see what Slic3r is reporting as being the perimeters extrusion width (which is controlled by the extrusion rate and is not necessarily the same as the nozzle size). You will probably find that it is 0.4mm, which would make 3 passes correct for a 1.2mm wall. If that's what you find, the issue is that you are under-extruding. You can adjust the extrusion multiplier by trial-and error, or you can print a cube with 1 perimeter, no solid top or bottom layers and no infill Measure the wall thickness of the result with callipers or a micrometer and use that to calculate the required multiplier to use (multiplier is [expected thickness]/[measured thickness] ).

You can also manually set the extrusion width to use under "Print Settings" "Advanced" and it may work better if you set the default extrusion width to 0.3mm.

Dave

Ahh I see, yes it says:
; perimeters extrusion width = 0.31mm
; infill extrusion width = 0.31mm
; solid infill extrusion width = 0.31mm
; top infill extrusion width = 0.31mm

So I would need to edit the Multiplier to get it to come out correctly as .30mm

Right now the Extrusion multiplier is 1 so to maybe change to .9

So will that make the printer do 4 passes instead of three to make the wall like is needed? I will test tonight and see what it does.

I did several test prints last night and adjusting the Extrusion multiplier did nothing, not sure what is was suppose to do exactly. Anyhow I test the second suggestion, default extrusion width to 0.3mm and that fixed my issue perfectly.

Also tested changing that setting to .2 and it squeezed and extra row in the pass, which made the wall just .1mm wider, but much more solid so I may use that if I project with thinner walls.

There's a massive long thread somewhere about extrusion width over layer height, the cross-sectional profile of the 'line' of plastic as it is laid down on the print surface and how it interacts with the lines next to it, but the short version is that a 0.3mm nozzle should print at a width >0.3mm. If you think about how filament is extruded out of a circular hole, if you set the width to be the same as the hole aperture then you're effectively telling the printer to lay the plastic down without squishing it into the bed/layer below. Slic3r tries to automatically calculate the optimum W/T ratio based on your settings but I don't think it takes into account the material and therefore the different demands it has on the W/T ratio - the Tantillus basic calculator is a good start.

As an example, I use 0.5mm extrusion width with my 0.4mm nozzle, which has the nice benefit that I can print walls in integer multiples of a millimeter.

Quote
AquaticsLive
Ahh I see, yes it says:
; perimeters extrusion width = 0.31mm
; infill extrusion width = 0.31mm
; solid infill extrusion width = 0.31mm
; top infill extrusion width = 0.31mm

So I would need to edit the Multiplier to get it to come out correctly as .30mm

Right now the Extrusion multiplier is 1 so to maybe change to .9

So will that make the printer do 4 passes instead of three to make the wall like is needed? I will test tonight and see what it does.

You might see a better result if you forced the width to 0.4mm. The extruded width should be greater than the nozzle diameter for best results. Or change the width of the wall to 1.24mm so that the default .31mm width can get in 4 passes.

Dave

Edited 1 time(s). Last edit at 08/15/2014 12:11PM by dmould.

The other way around would be to fix the extrusion width to 0.3 mm, essentially all widths in Advanced tab of the Print Settings.
To fully complete the trick, also set the nozzle diameter to 0.29 mm.
With the two changes above, you'll always be in control of the printing width.
Please note that this apply to Slic3r only.

Thanks much for the advice, I am giving all the ideas a shot tonight and will send an update. Just making a 2mm test wall on top of a small base. Should give me more pretty acurate idea of what makes this work.

Wow what a difference, problem fixed looks so much better.


So first piece was to get my layer heights figured out. I used the calculator that QuackingPlums suggested. It helped me learn what was going on with the height and width. Now I did not use the settings it had since it didn't have 0.3mm. I used some math from what seemed to work for the .4mm and converted it to my .3mm to set my layer height.
0.3 * 0.675 = .20
Layer Height = .20
0.3 * 0.875 = 0.262
First Layer height 0.262

That really didn't do much but make my print flatter and rows stacked nicer, but I had gaps in the wall yet.

So with 3Dmaker4U's advice I changed the extrusion width to 0.3 mm and changed the nozzle diameter to .29mm and bingo my test wall came out perfect, I checked them with the calipers and I am within .1mm of my drawing. That is the best I have ever seen. So the combo of the two really makes the plastic squeeze together into one solid wall, I am guessing the curve of the extrusion leaves negative spacing. So to compensate for that missing plastic you have to squeeze it together.

So thanks much to all for your advice!