Beginners thoughts and questions.

Hello. Slowly moving forward learning 3d printing and Slic3r. A bit to slow, but I don't have much spare time. But! I am able to print some things, with my delta printer! Today I even printed a T34 tank model 1:100 scale, smooth as a glass! In ABS! Wow! I am the best dad in the world, as my children say (and their friends to)

But I still have some doubts about printing strategies in Slic3r.

First things first - raft. I need it. I can't print good without it, because I don't have a heating bed. So, raft in Slic3r does not have surrounding perimeter line. If filament didn't stick at the beginning or at any edge - whole raft goes bad. I can add a brim, it's a lot better, if it sticks. But as I understand, brim is calculated after raft, so it is made of small twisty edges, that always try to runaway from the surface, not the straight lines, that will stick for sure. How to fix that? I know about the table, I will buy one soon, but I am not the only stupid guy without heating table, I think many people will agree - straight or even smooth lines are better than "nervous", they stick better, and even they are shorter. Why don't we calculate brim first, and then raft? Or am I wrong?

Second - about the raft again. Lets say, I make raft of 3 layers. First one goes with a big step between the lines, second one with smaller, but... They go same direction! First problem here is that if first layer didn't stick, the second wont either. The upper line can hold only for the bottom line, because they go same direction. Second problem is a step. I must calculate step of upper layer to be at least 1:2 of bottom layer, because if it will be 1:3 or 1:5 - I can't make a flat surface. One line will be right on top of the bottom line, others will be somewhere in between. Shouldn't it be that upper raft layers are 90° turned against bottom line? I think, then we can add as many layers we want. What you say?

About Infill - beautiful!!! With Cura I can't make it so smooth! Thanks a lot!!! But, sometimes something strange happening, can anyone explain why is that? For example:
I wanted to print a turret, Settings were
Infill:0 (automatic)
Solid Infill 110%
Top Infill 130%
Slic3r successfully sliced model, with full fill of bottom circular part. But when I started printing - in the bottom of model, in that circular part it started filling to much of filament. I changed settings for solid fill - nothing changed. Changed top layer fill - nothing. So, Why sometimes it fills to much of filament? In slic3r it looks as a bit smaller red (infill?) lines. The model itself is ok, no non manifold edges, clean and beautiful. Diameter of this circular part is about 16mm. But It happens sometimes on bigger details, plane wings, for example. Sorry, can't show it right now, But I hope you understand.

And the last for now - Support material, Pillars. They are cool, but they sometimes brake during printing, because of a small base of pillar. Can I make a wider base, depending on each pillar height?

Thank you for such wonderful software!

And, Sorry for my English

Kostolapy,

I made a page in the Wiki for Slic3r tutorials that might be helpful: [reprap.org], and I can try to answer a few of your questions:

The first thing you need to do is make sure your bed is level, and then improve your first layer height calibration. Having that consistent will make the biggest difference. Print a first layer, and measure the thickness - it should match what you set in Slic3r. A feeler gauge is more consistent than using a piece of paper. A bed probe is a very good investment.

If the printer is not enclosed - even with a plastic bag over it to keep off drafts can help.

A brim should help some with supports breaking off the bed as well. For tall supports: Rectilinear infill is stronger. Tall thin supports are a problem. If you are designing your own parts, then you can design them with some of the support in place. Meshmixer is a free program that will allow you to draw in supports - not very easy tho.

I recommend getting away from all automatic settings for speed and extrusion width, then you can tune your printer properly. Note that there is a bug in Slic3r that will cause the infill to be over extruded with some automatic settings.

For extrusion width, the rule of thumb is to use a value that is > nozzle diameter, and < 1.7x nozzle diameter.
Use an actual value like .5 for a .4 nozzle instead of a %. (Percentages for extrusion width can make no sense depending on the layer height).
Use a wider extrusion width for the first layer and go slow - then it must squish wider to get that extrusion width, making better contact.

I can't comment on the raft pattern - I don't use raft unless I have to print an object that is curved on the bottom (a raft in that case improves the quality).

Hope that helps.

Edited 1 time(s). Last edit at 03/16/2016 10:14AM by Paul Wanamaker.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
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