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Adds a Support Gap option - fixes case when support extrusion width is very small #1058

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@cakeller98

when the support extrusion width is very small, then support ends up printed too close to object and is very hard to remove.

Although this is not the ideal fix for the support problems, this is important when the support extrusion width is small to prevent support from being too close.

note - the default is set to 150% of support extrusion width, so it should match your original math.

Another note, which is unfortunate, I don't know how to scale the value by the 1,000,000 that the $flow->scaled_width was scaled to... so it's hard-coded.

anyway, hope this is helpful.

@cakeller98 cakeller98 Support Gap option - fixes case when support extrusion width is very …
…small and support ends up printed too close to object.
421fe38
@cakeller98

is this more or less what you're doing?

image

and the nozzle diameter likely not enough of a lift... but maybe it is?
Height

@cakeller98

Experiment printing blocks without suppport between them... and single layer gaps (0.2mm)
nozzle size 0.35mm, layer height 0.2mm

modelled gap in the model from left to right 1.0 mm, 0.8 mm, 0.6 mm, 0.4 mm, 0.2 mm
actual physical printed gap ... see image.
image

After pulling these apart, I found the surface quality best on the 0.2mm gap but it was very very difficult to pull apart. 0.4mm gap was almost as hard to pull apart, and still had good quality.
the 0.6 mm gap was easier to pull apart, but had low quality infill, but that was probably due to the fact this is not done with the correct bottom surface math (I think) since I'm not printing with support, just stacking a floating block above another block support turned off.

I understand support needs to allow for precise model printing.
I also understand the goal is to be physically correct, and not just do soemthing because it kinda works.

However, at least as important to the precision is the ability of the operator to remove the support material.
If the operator cannot remove the support from the model without damaging the model (including fragile models) then the support is useless.

Not to mention, fragile parts are usually the ones that need support.

I know there are a lot of other priorities right now - but in the mean time, there was so much that was illuminated for me today regarding support - and i feel support is such a critical feature for 3d printing... so I wanted to contribute these thoughts.

Perhaps I should just invest in a dual extruder :) and dissolvable support material? :) But single material support / object is much more convenient... and less complicated.

whacky idea - what if we had a nozzle that leaked (by sponge) a mold release e.g. liquid soap, onto support material tops?

@cakeller98

Tested the whacky idea of a mold release with a 0.35mm gap between layers.
On one of the two sides, I painted liquid soap on the top surface of the bottom block
The blocks that had the thin layer of liquid soap (mold release) separated with very moderate effort (thumbnail) it was firmly adhered, but not welded. in other words quite stable, but just not well stuck.

The other block was so attached it broke the blade of my exacto, and was very difficult to separate.

And it should be noted, these layers were separated by a nozzle diamter (0.35mm), with 0.05mm layer thicknesses...

nozzle diamter (0.35mm) was not enough offset to prevent over-strength adhesion.
However with the mold release it was an excellent gap - for this layer height and nozzle config.

image

here's what the gcode looked like:
image

@nophead
@cakeller98

@nophead Cool I'll check it out... however soap is cheap too, and much easier to clean up than oil.

Checked out the post - it is a cool idea... I don't like the oil as release agent, but I love the felt (or sponge-tip) pen idea.

also doesn't have to be exacting, just good enough... now if I can get @alexrj to allow for a different extruder for the support-interface layer, then I could just attach said pen to my bot with minimal effort! :) gotta print the support normally up to that interface layer :D

@cakeller98

@nophead

Sakura 38550 4-ml Tank Koi Water Color Brush, Small by Sakura

Permalink: http://amzn.com/B0015AWS8Q

will be testing to see if it could work with a glycerin based soap (maybe thinned with water just a bit)

@cakeller98 cakeller98 closed this Mar 20, 2013
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