Support material idea

There has been lots of talk about using a second extruder to print a hypothetical 'support material', however, there doesn't seem to be a good idea of what this material might be.
The criteria seem to be:
-readily available
-easily dissolved
-strong enough to use as support

This is going to sounds strange, but has anyone considered chocolate?
It's readily available, reasonably strong, and because of a low melting point, it can be removed in boiling water.
The only problem I see is how to make a decent extruder. Perhaps you'd need a basin of molten chocolate, relying on gravity for extrusion, or perhaps someone can come up with a better concept?

Yep the guys have though of chocolate.
In fact people were talking about extruding nothing but chocolate as an example
of why open source is cool and can be adapted to your own needs.

Stephen

An issue with the support material is it needs to not completely liquify and run all over the place when 200 degree C plastic gets put on top of it.

I've found some water-soluble thermoplastics with melting points in the 120-130C range. Probably still a bit too low, but who knows.

Of course, any kind of plastic would sort of depend on an extruder that can deal with granular plastic :-(

Rosin, perhaps?

It is fluid at temperatures as high as 130C, and dissolves in alcohol.

It's brittle in its solid form, however, and causes enough friction that it's commonly used for this purpose. If the extruder issues could be worked out, it's cheap, renewable, can be manufactured on a home scale from pine trees and would serve the purpose.

... i was thinking another way:

With lowcost high-power diodelasers (i already have an 1Watt type with fiber and 0.06mm spot and will receive soon a 20Watt-LD with fiber and optics too) you can build a powder-sintering device, where the toolhead can melt/sinter a prelayd powder-surface or even better - apply powder through a small tube and melt it to solid or leave it as support.

So you can 'draw' the trays of the object as with FDM, but you've also supporting powder around for fabbing overhangs.

With this method you can apply powder-support at will and locally - maybe with a shell around (fabbed analog layerwise) and filled with powder until it's an even surface and then fabbing the next layer.

Or you omit the support and apply a tilt+pan-device for real 5D-fabbing as in commercial steelpowder-sintering machines ...

Viktor

How about using simple sand as support material?
When the software detects support material is needed on the next layer, it adds sand to those places that are going to need support. It keeps adding sand until the sand cone is high enough (This would need a detector that triggers at that instant, for example a small photodetector at the same height next to the nozzle, which would get covered with sand, and thus receive less light. (Bit dodgy, needs work))

The sand would not interfere with lower layers, because that's already done. The only problem might be that it sticks to the overhang, but that would be a mainly aesthetic problem.

Hmm, looking at it written like this, it doesn't seem ideal The biggest problem would be the detector, as far as I can tell.

... look at the 3D-printers from Z-corp or the DIY-inkjet-3D-printers - here a roll pushes the powder from a reservoir over the building area and then the inkjet rints the next layer of glue.

Something similar schould be possible with sand or another supporting powder, but then you have to cover the complete building area, instead of some virtual enclosing shells with a co-fabbed border ...

Viktor

The problem with powder-bed-based systems is that they are totally different mechanically from what we have with a "typical" RepRap system. It isn't just a toolhead you can bolt on, or a new kind of material you can use in an existing head.

One issue with any support material is that it will invariably mix with the plastic, at least at some level, so you will get a bit of contamination. Anything granular, even if it dissolves or is removed, would leave a rough surface (at some level) behind.

Another alternative might be a gel that maintains a relatively constant (high) viscosity from 20C up to 250C. I don't know if such a beast exists. But if it does, it could be dispensed with a syringe-based toolhead, like what they use with Fab@Home.

I don't know a lot about the thermoplastics that are available. I know ABS is *around* 220-240C to melt it - what are PLA and HDPE like in terms of melting point?

Actually ABS melts at 105C, we extrude it 240C so that it bonds to the layer below, HDPE 130C, PLA ~160C.

The function of support material is not just to hold up filament against gravity. It needs to perform the same function as the base material. I.e. something for the filament to adhere to and be held in place so it is not dragged around by the nozzle and also resists the curling effect due to shrinkage.

So it can't be a powder or sand, it has to be something that sets solid and has a melting point similar or higher than the target material.

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[www.hydraraptor.blogspot.com]

When the football world cup was held in Korea and Japan, the Japanese sprayed an adhesive over the rubble that train tracks are bedded on so that activists opposed to the competition couldn't easily grab the rocks and throw them at trains. It still allowed the rubble to shift underneath, so the vibration from the trains' progress didn't travel through the surrounding ground, as normal. Starch used as a support bed could maybe be misted with water so the top surface binds to a contiguous surface that suits the criteria?

Take a look at this patent. It talks about a material called poly (2-ethyl-2- oxazoline) ("PEO") that has the properties we would want. "sold under the tradename Aquazol by Polymer Chemistry Innovations Inc., of Tucson, Arizona" Google gave me this: [www.polychemistry.com]

From their web page, "Aquazol possesses excellent thermal-processing capabilities and is one of the few water-soluble polymers that can be extruded."

Of course, its use as a support material for FDM is patented... There are also obvious "it probably isn't available as a 3mm thick wire on a reel" issues as well.

[www.wipo.int]


The patent also notes some alternatives, that have issues (e.g., high degree of shrinkage). Such as polyvinyl alcohol and polyethylene oxide.


EDIT: added quote about Aquazol

Edited 1 time(s). Last edit at 10/29/2009 04:56PM by quadshop.

Thanks for your help guys.
Will have a go later today.

Why not use a support like SLA? SLS support is the material itself built in a small delicate but strong latice structure that you just break off. Everyone uses rafts for the first few layers that peel off why not do this all in software and just have a suport structure that is made from actual material that breaks away easily. No fabbing more heads, no firm ware and software updates other than just adding a support generation plugin that will analyze the geometery and generate support structures.

Curlrup,

That's an incredibly good idea and I'm really surprised that no one has commented on it yet.

If I understand you, you're proposing a software fix: adding a bunch of thin filaments built into a raft-type structure designed to be easily snapped off and trimmed with a utility knife.

That's brilliant, that's doable and should completely happen.

One could calibrate the extruder by designing a 'break test' model that prints a solid base that has a cleft in it which widens along the Y axis, then prints single filaments over it along the X axis. The operator would note how long the extruder is able to bridge before it either sags to touch the bottom of the cleft or breaks, and that information would be used to determine the pitch size of the raft.

This is so much easier, once implemented, than two heads. It boggles the mind. Someone needs to try this!

... this was tried and made, you have to search the last year for something like "spacecraft", "toy" or something similar.

I can't remember who posted the pictures, but he made a support-structure of easy removable strings with the same material ... maybe with playing around with the infill-parameter ...

Viktor

What's needed is some generalized tool, a panel in Skeinforge or similar that automatically calculates a support framework based on a given 3-d model.

Obviously it can be crafted by hand, but to qualify as a real solution it needs to be as transparent to the design process as possible. Simply design a model, prep for printing, and the support framework is generated by the software based on nozzle parameters etc. that can be calculated as suggested or in another fashion.

I don't program, so I'm not the one for the task. But this would be super useful and great, and would get around a lot of problems with printing arbitrary models.

I am pretty sure that Skeinforge already does support material automatically. IIRC, I have seen people blog items using it.

A second material with a solvent is needed for the general case though to be able to remove support that you cannot get to. E.g. a mechanism with captive moving parts.

Edited 1 time(s). Last edit at 11/06/2009 03:42PM by nophead.

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[www.hydraraptor.blogspot.com]

Oh. Nev'mind!

Shows what I know abt. the state of home 3-d printing,,,

Yes guys, the breakaway support is well implemented in Skeinforge. You get a lot of ooze because is changes temperature all the time but for the rest it does work well!

Has anyone looked at PVA Plastic as a support Material?

From what I read its water soluble and can be engineered to melt at various temperatures.

I havn't looked into it very hard, but heres one of the links I have read.
PVA Plastic

I'm planning on experimenting with PVA. I ordered some in a powder form. I'm trying to think of a way to extrude it to make a support material. The syringe design with a heated barrel might work.

I doubt I'll get around to it for at least another month though.

Support Material Idea: Instead of using another material (plastic or what have you) what if the support material was the same as the build material and we just put a thin layer of releasing agent between the build and the support material?

This of course only works for some build shapes (you need to be able to get the support parts out), but should be easier then trying to use two materials, no?

Something as simple as cooking oil could work for this.

Support material has to hold the layers above down to stop then curling upwards. It also has to stop the filament from being dragged around when the extruder turns a corner.

That means the support layer has to perform exactly the same function as the build table surface. I.e. the object has to bond to it with considerable strength and still be removable without damage.

Adding oil has been shown allow objects to be separated: [blog.reprap.org] but it may be difficult to get the bond strength just right.

To be able to make all shapes and mechanisms with moving parts we need a soluble support material.

Edited 1 time(s). Last edit at 11/18/2009 12:25PM by nophead.

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[www.hydraraptor.blogspot.com]

hmmm, fair enough

The initial poster was discussing chocolate as a support material. I was watching a TED video (http://www.ted.com/talks/ross_lovegrove_shares_organic_designs.html), where Ross Lovegrove says this around 6:50 :

"This is a meringue... A meringue is made exactly the same way, in my estimation, as a bone. It's made from polysaccharides and proteins. If you pour water on that, it dissolves. Could we be manufacturing from foodstuffs in the future?"

Now, egg whites are probably a messy thing to be using in manufacture. But perhaps making support materials where the bulk of them is made of sugar would be a good starting point for a support material recipe.

well that is a very ideal thing to do...

and also, it sounds yummy!
LOL><

I love sweets!

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