Support material slump

So, I've been thinking about how support material would need to be deposited. Right now, it seems as if the build material needs a 50% overlap, allowing Vik's liquor glasses. What if you used a support material which wasn't necessarily hard enough to support itself, but hard enough to support the build material? So, instead of being able to work with a 50% overlap like the build material, the support material needed a 150% overlap? That is to say, we could use a support material even if it had bit of slump to it.

As long as the support material is inexpensive enough (and drywall compound is one such material), then "wasting" some on a 150% overlap wouldn't be a big deal. It would just be a question of post-processing the design so that any overlap less than 50% would have its "shadow" cast downwards, expanding by 150% on each layer. Maybe that could be done by post-processing the STL file?

I just made up the 150% number -- actual research with the support material would be required to get a real number.

I've been thinking it'd be workable to build the part in a box, and keep the box topped off with something granular. Sand perhaps. As you build the part, build the box around it, deposit filler material within the box, then scrape the box level before proceeding with the next layer.

How about using water for support material?


Build the object inside a watertight box / container, and add water after each layer to keep the water level at the current layer.

It would have the advantage of very good cooling, which might maybe avoid the problems that arise from slow shrinkage during the build.

The plastic is about the density of water, so it might be possible to do large overhangs with the plastic supported by the attachment point and the surface tension.
Of course, suspended structures (where some part is only supported by another part above it) would be impossible to do with this approach.

Why not use play-doh as a support material? especially the home made versions. It would support well and be easy to remove.

... maybe low-temp-melting wax (parafine/stearine?) is usable as easy to remove support?

When i once had to optimise/debug a heatcuring glue-dispenser-system, the problems were drastically reduced, when i wound a heating wire around the dispenser body and the outtake/needle and put some aluminium-foil and a foam-hull around the complete dispenser-head.

With this i could set and hold temperatures from 40

A friend heard of the idea the first time and suggested glass granulate of something between 50 and 70

Edited 1 time(s). Last edit at 11/13/2007 03:54PM by Antsan.

Hi Thomas,

... i have a kilogramm-probe of ~100-micron glass-spheres from Kisker, which are dedicated for high-accuracy surface-finishing.

When i observed the quality and size-accuracy of the spheres, i found different sizes from nearly 5 microns up to 1 millimeter (most between 30 and 150 microns), some broken particles and needles and bulks of coagulated spheres.

The consistence isn't really as water, it's much smoother then sand, but it forms pyramides and waves, as sand too, but more flat.

When you put plastic on the surface, the spheres attract to the plastic (much of the attracting force is pure electrostatic) and would be embedded in the melted tray too - especial the smaller speres, so you have to deal with embedded glass-spheres.

Viktor

Thats what I/the other one meant with the last comment. Those little spheres could support the material if you use quality stuff of 40 to 70

Hi Thomas,

... my probe is the same stuff for 'steam-cleaning' (in german 'Glasperlen-Sandstrahlen')

It's obvious, that in the 'normal' grades you have a wide variety of sizes and broken particles, because of the manufacturing process - i think it's made with spin-exhausting of melted glass ...

When i searched for better size-accuracy, then i found nearly 'perfect' glass- and plastic-spheres for biotech applications, here you have grade-qualities from 90% until 98%, but with 'astronomic' prices - i have an offerte with 98%-grades 100-micron-spheres for 300

And that says, it's just not effective, if I don't get you wrong.

Then there would be the idea with the fire extinguisher stuff. I don't really know about that, I'm just posting the suggestions someone else made.

Hi Thomas,

... yes, the normal glass-spheres for 'stream-cleaning' didn't have a good quality and the separated are much to expensive - but maybe with a quick'n'dirty cleaning process we can pure the cheap stuff to make a try ...

AFAIK the spheres in the fire-extinguishers are brittle hollow spheres or with antioxidant fillings, but should behave in the same manor.



By the way - if you drop into the german reprap-group and localize, then it's a bit more populated

Viktor