Is it me or the First Layer Extrusion Width setting is inverted?

I'm not sure at what point I changed some settings and the first layers became too rough, too much material was being extruded, so I started reducing the First Layer Extrusion, and still bad, reduce more, even worse (???) after fiddling for a couple hours, I had an idea and I increased the width to 200% (I had gone all the way down to 30%!) and voila!, nice first layer.

So, yay, I figured that out but it's very confusing, or at least I don't understand the logic of increasing the extrusion width to reduce the extrusion amount.

Hmmm... I think I understand what may be happening, correct me if I'm wrong.
By setting the First Layer Width as a percentage, let's say 50% with a 0.4mm nozzle it rasters the layer in 0.2mm passes, but apparently it doesn't reduce the amount of material extruded, therefore it piles up and makes ridges and bumps.

I printed a test object at 50% First Layer Width, with manually reduced filament flow to 50% and I have to say the surface finish is amazing, it's impossible to see the printing lines compared with the one on the right, printed with the default 200% first layer width.

That number changes the extrusion width as a percentage of the layer height not of the nozzle diameter. So it does change the amount of plastic coming out but it also spaces them different.

I think the setting you were actually looking for was Z offset which changes the distance the nozzle is away from the bed thus making the first layer more or less squished.

So for your 50% pass if you had a 0.3mm first layer height set, your extrusions would have been 0.15mm wide which is actually too narrow (may be ok for the first layer if the nozzle is too close to the bed). The default of 200% would have made the extrusion 0.6mm wide which is about as wide as a 0.4mm nozzle can print. Either way using the percentages is a bad idea and should not be available to the user. Since if you change the layer height you do not want the width to change that dramatically. An example would be trying to print low layers like 0.1mm. With the 200% default it would try and extrude a path 0.2 which is too narrow. But if you had it set to 0.4 it would not matter if you changed the height since it is an absolute width of 0.4mm which is fine with your nozzle. This is made worse since it does not take into account the nozzle diameter at all. What if you were printing with a 1.5mm nozzle and the first layer is set to 0.3mm and the width is set as 200%. The resulting 0.6mm wide path from the 1.5mm nozzle would be useless and give completely unusable results.

Edited 1 time(s). Last edit at 02/15/2014 04:59PM by Sublime.

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This percentage of extrusion width also lead me to bad results. I did read the (to fast vanishing tooltips) but I guess I mixed the layerheight with the extrusion width.

So I ask me the Question, why is it not a % tweak of the default (calculated by slic3r) extrusion width or the Nosszle width?

happy print,
Carsten

Hi,

I always used around 200% and got bad resuts now... in Slic3r 1.0.0 stable

the Captain is right - I made a few Slices to see what happens changing the "Extrusion Width setting" and it is the case taht it works vice versa than before !



BTW. from my understandig now it works right - reducing the Width reduces the spacing... thats what I expect
...same for the Top Layer

Edited 1 time(s). Last edit at 03/30/2014 11:31AM by Printcontrol.