Checkout Prusa's Skeinforge Enhancement

0.2 mm layer quality with 0.4mm speed:
[prusabuilders.posterous.com]

and some photos he posted:



Edited 2 time(s). Last edit at 12/25/2010 07:30PM by Greg Frost.

Hi Greg,

Prusa has done some excellent work here but if im honest I still prefer the lower sample, it might not be as "smooth" but it looks more defined and accurate ??

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Cheers,

Paul

Has anyone been using this plugin with SF 40/41?

I ask because the Volumetric Dimension should now make this ~trivial to do right with little/no tweaking.

I think the plugin only affects shell layers, but the idea can be used to also improve vertical/cross-sectional resolution with domed surfaces and curves.

for an example, look at this thing: Nautilus shell

it's a nice print, but looks like a topo map, or rice patties on a mountain side. this is particularly apparent at the top of the object, where it's nearly flat.
so i think the plugin can improve these types of shapes with a small tweak

These images were mocked up in MS Paint, so just imagine they are of the same curve :-)

Here the layers are the same size (lets say 1)

Here, the layers are 1 when angles are are near 90 degrees (+/- 45 degrees, maybe) , but switch to .5 when angles move close to 0/180 degrees. This should be much easier for skeinforge to do properly with volumetric Dimension, i think.

So the gist is that, past a certain user-specified degree (like 45), skeinforge would reduce the layer height by some percentage.

Edited 1 time(s). Last edit at 06/15/2011 09:35AM by Buback.

It's a step in the right direction. never the less.

I don't know if you're ever going to get overhangs to print correctly without support. Your images there are a good illustration of the basic problem; there's just nothing to print on when the angle passes 45 degrees.

Maybe if the nozzle could tilt, so that it was still mashing the new layer (nearly) straight into the old layer. Or maybe if you could have some kind of moving support structure, like a little "hand" underneath the nozzle. At the moment the printer is simply relying on the new layer to be sticky and "pull" itself onto the old layer.

Or, perhaps skeinforge could treat thin walls like pixels. If you want to turn a vector into a raster you have to tell the program whether or not to use solid black/white pixels or shades between black and white (anti-aliasing). The slicing program could expand a thin wall along the plane of a layer just enough that there would be something no less than 45 degrees away from where the next higher level is going to start. you could just tell the program whether the dimensions of the inside or the outside of the curve are important. Maybe it could even use small ridges at regular intervals instead of widening the entire wall.

I'm not really proposing this technique for overhangs (i should have chosen a better example image, as the shell is all overhangs), but rather just for top layers.

However, I don't think that overhangs should have to be handled differently, as long as they follow our rough rule of 45 degree max. skeinforge would simply reduce the layer height by half, for example, and then create the path based on that layer height, not the original full layer height.

I wouldn't expect any problems in principle. I imagine that maybe using different layer heights in a single piece might effect it's strength, or change the way a piece warps when cooling. On the other hand. if it is the case that it effects the way a piece warps, maybe using different layer heights in strategic places inside a piece could be used to combat warping. but that would have to come much later.

I also want to say that i don't have the talent to do this coding, but just wanted to present the idea.