Support material candidates

I have thought for a while about a cheap and easy to use support material that might be used. There have been several materials proposed but my approach to this is that it should be as easy to obtain and prepare as possible, as well as easy to work around and remove once the piece is finished.
Also, being non-toxic would be a plus.

The first thing that came into my mind was Gelatin, but It has the drawback of setting to slowly for our needs.

But then what about Agar Agar? (http://www.bulkfoods.com/agar_agar.htm)
This stuff can be made to set faster (seconds) at higher concentrations and it melts under heat to a syrupy liquid. Heat and concentration would be the only parameters to be controlled and twitched to make this work.

What would be the best solution for heating for example a stainless steel marinade syringe full of AgarAgar up to around 85

Ok, my curiosity was such that on the way home I went to a nutrition shop and got me 200g of Agar Agar for 11

How about using the same plastic extruded at a lower temperature so that it doesn't weld so firmly to the printed piece. Make it a different colour so you'll know which bits to peel off.

Hi Fernando,

for easy heating below 100

Adding color would be very easy indeed, like easy to get food colorants.
I'm currently making some tests in my kitchen, keep posted, in 10 minutes I'll have some thrilling updates!

Jim at New Image plastics, the firm that makes my filament is always on to me to let him put colours in my filament. He apparently just hates plain white filament. No additional charge.

Yeah color is such a great plus.... today I have been dreaming of printing a new body for my glasses. I just grew tired of the ones I have and thought how cool it would be to have many different sets to juts wear for whatever mood you have.

Ok, so here are the first results!

A mix of 2g Agar Agar with 100g of water results, once cooled down, in a rubbery gel, quite more stiff than regular Gelatine. The stiffness is probably not enough to make 3mm rods, as they would fall apart.

A mix of 3g Agar Agar with 100g of water is little stiffer. I will try adding starch to the mix to achieve greater toughness when cold, so that rods could be formed.

As for pouring fused thermoplastics over the resulting gel, I have taken a polypropylene stick and set it on fire, waiting for it to fuse and cause drops to dribble over the Agar Agar. It didn't melt! Apparently it contains so much water that the PP didn't have enough stored heat when liquid to melt the gel.
The most I could see was that the resolidified PP surface was rough due to microscopic bubbles, probably water vapor bubbles, released due to the above 100

Edited 2 time(s). Last edit at 04/24/2008 05:48PM by Fernando.

Melting the gel in the microwave is very easy!
It also accepts a lot of fillers. So far, sand-dust or clay dust have had the best results in respect of adding better mechanical stability and thermal resilience to fused polypropylene.

I think this stuff really is ideal as support material for the FDM process.
The only point to be solved is how to deposit it, be it by creating 3mm rods solid enough to be used in a standard extruder or by having a melting reservoir heated at about 100

Agar is not very reusable. Sure you can melt it down into a liquid again, but it just so happens that agar is one of the absolute best growth media for bacteria.(http://en.wikipedia.org/wiki/Agar_plate) So after a couple of uses, it might get little gross. (http://librarynews.rockefeller.edu/?p=24)

Fortunately, it can be made from certain types of algae.

Will the Polymer stick to it when extruding as this is a requirement, otherwise the filament will just drag over the surface. Commercial FDM machines put down a layer of support material to make a raft then build the model on top of this. If we try the same approach this would prove the viability of the material even if we don't finally use the raft method.

Regarding bacteria growth can we not simply steralise the stuff every few uses.

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Ian
[www.bitsfrombytes.com]

On the bacteria issue, adding some antiseptic to the mix would also do the trick, like soap or bleach.

I only tried with PP over the agar. It stuck very lightly, indeed, but not enough to require heavy force to remove it when cold. The question being: how much would it be necessary to stick?

Enough to resist the force excerted by the warping, which is considerable, otherwise it will curl awayas the layers above are added.

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[www.hydraraptor.blogspot.com]

That much?
That's quite a tall bill! What you are looking for is a remedy to shrinkage, I don't know if any support material can give you that. Bodies, when cooled down will try to shrink. If you don't let them, which requires some serious tension bearing devices, they will become tensioned. IMHO, a "sticky" surface is just not a good enough device to maintain and counteract the tension created inside a large-ish contracting volume.

Edited 1 time(s). Last edit at 04/25/2008 07:08AM by Fernando.

The biggest improvement to warping I have got is to use a stiff base material that bonds well to the polymer, holding it flat until it has cooled. E.g. PP for HDPE.

There are two support roles:

1) Allowing internal voids by supporting a bridge of polymer. For this you only need something to resist gravity and that can be dissolved to remove it. You can run filament over this provided you don't change course. Agar may well work here.

2) Supporting overhangs. For this you need to be able to change course so it needs to grip and it has to hold the polymer down against warping. Because it is on the outside you can get at it to remove it. Probably the best candidate here is the polymer itself. Lay the support layer slightly low so than the layer above has a small contact area, forming a weak weld, that can be peeled.

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[www.hydraraptor.blogspot.com]

I understand. I'm not so familiar with FDM printing strategies, but I do get from your explanation why grip is important. And I agree that the best candidate for support material in that case is the same polymer.
Maybe a combined approach to the support role could be applied: use agar or similar for the gravity support material and columns of polymer for specific points where grip and warp avoidance has to be achieved.
Know what I mean? Don't know if my explanation is making any sense here...

The lower bed on which the object would be printed upon would best be a heavy Polypropylene board, as I think you have mentioned in other posts

Yes it would be nice if we could find a universal support material that does both roles for all polymers, but I fear that may be impossible.

So far I can only get HDPE to stick to HDPE and PP.
PCL and PLA are "sticky" when molten, so will stick to porous things that are not thermal sinks, like balsa wood. PCL even seems to stick to hot metal, like the extruder nozzle, and is quite difficult to remove.

ABS seems to stick very well to what I think is PVC laminated foamboard.

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[www.hydraraptor.blogspot.com]

Our school just got a Dimension machine and the support material it uses is ABS. Since the machine prints in ABS this makes sense. Their strategy, I think, was to use a "polluted" ABS. It seemed like the support material had some sort of grit or dust in it that cause it to be very brittle and weak.

I'm pretty sure we can create a filament extruder with a melt reservoir in which can be placed virgin ABS and some sort of appropriate contaminate.

This same strategy can be used for all the plastics.

Demented

Has anyone tried bonding other plastics to PCL? My thinking being that it's melting point is so low that it could be washed out of the finished object with hot running water, caught in an ice bath and recycled. If it was necessary to raise the thermal mass of the PCL it could be mixed with clay slip. This would make it melt more slowly but at the same temperature and possibly increase "grippyness".

My worry about mechanical separation is that it gets tricky if you have small or convoluted spaces inside larger surfaces or fragile component bits near large voids in either case you can get failure, either by not getting the space empty or by damaging the smaller part. Also, mechanical separation of complex or repetitive structures could present problems, think about removing the support from a hairbrush or a heat sink. Lastly mechanical separation is going to involve either people doing something boring or high end machine vision, neither of which strikes me as a good use of resources. A support material which is thermally distinct ( or perhaps one based on distinctive solubility) means the finished object can be dumped in a tub of sloshing water for a few minutes and retrieved ready to go.

I have not tried bonding to PCL, but you certainly can't wash it out with hot water. Even with boiling water it is a very thick, sticky, plastic (we extrude it at about 140C).

I think it would be hard to get it out of inner surfaces. It is quite hard to remove it from the outside of the extruder nozzle even when it is at 140C.

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[www.hydraraptor.blogspot.com]

Perhaps I am confused, is PCL the same as "Friendly plastic" or CAPA? This was the original plastic tested on the extruder. It becomes very soft in hot but not boiling water. If that is not feasible has any thought been given to something like play dough or some sort of water soluble material?

I think someone had tried cake frosting at one point.

Hey Brian,

PCL and CAPA are one in the same. PCL is the scientific abreviation, I think it P-oly-C-apro-L-actone. Its coined CAPA by the guys in the business cus that just sounds cooler. Or at least that my impression of things.

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Jay

"I think someone had tried cake frosting at one point."

I think you have to be careful with all this. Virtually EVERYTHING has been suggested. Right off hand I can't think of anybody who has a two extruder system, one for plastic and one for support material, actually working and demonstrating that even one of the many suggestions actually works.

I may be wrong on that, but I don't think so. I know Adrian has built an extruder for polyfilla and, irrc, a few other things. I haven't, however, heard him say anywhere that he tried to print PCL or PLA over it, though.

Yes it is Friendly plastic which goes soft enough for moulding by hand at about 60

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Ian
[www.bitsfrombytes.com]

Are you guys considering using wax as a supporting material? It would be extremely easy to reuse. The downsides would be it's tremendous modulus of expansion/contraction with changing temperature and the fact that it might melt away when hot plastic was laid down on it.

Edit: on thinking about it a few more minutes, thermoplastics would be far superior to waxes unless you were extruding chocolate or something.

Edited 1 time(s). Last edit at 05/30/2008 07:46AM by rodzite.

What about sugar? If you ever made candy sugar is pretty good and works around 120C. It may be a bit high. Plus it isn't toxic and you can dissolve it in water. Plus it's tasty.

I'm surprised that nobody is taking into account the extra time it would take to print one part. It already takes a while, and with printed support it can double or triple the print time depending on the shapes. Then the computer would also have to figure out where to put the parts and switch back and forth between extruder heads and and material and also keep 2 heaters active at the same time.
Isn't there a way to mix extrusion RP with something like powder support that 3DP and SLS uses.
[upload.wikimedia.org] something like this would kinda work with the right type of application process and be fast per layer and really easy to get off (unless you make a closed hollow space).
Imagine printing this (http://www.zcorp.com/images/155_002.jpg) and trying to clear out the holes with anything less than powder. Check out zcorps website, they have some nice printers at good prices (starting under USD 20k) and can do multi-color too.

With this method you could also use something as cheap and easy as sand as the support material.

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printed support it can double or triple the print time depending on the shapes

Thats the way it goes, unfortunately. Given that you have to cover extra area, how can it be otherwise? Perhaps a clever dual-headed print setup would reduce time a little, but only by so much.

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switch back and forth between extruder heads

I mentioned that I thought that having a dual-headed printer was a good idea for precisely this reason. Others seem unconvinced of this however

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With this method you could also use something as cheap and easy as sand as the support material.

Just pause briefly for one minute, and consider that pretty much every support material idea being suggested has almost certainly be thought of before, and generally rejected.

Sand, I suspect, would make an awful support material.

The support material needs to be robust enough to resist the contraction of the filaments laid down upon it. It needs the filament to stick to it, otherwise the freshly deposited strands will probably end up being dragged around by the toolhead as it moves away, which is what usually happens when they fail to adhere to whatever subtrate they are being laid upon. Witness the thought nophead has put into making rafts.

The zcorp stuff can use powder because it uses a rather different printing technology to us. Conversely, reprap can make far more substantial and robust items than any zcorp printer, no?

I think commercial extruded polymer rapid prototypers use a solid support, which can be broken off, or in some cases dissolved in a weak acid. Of course, I only know this because someone else mentioned it on here, so take it with a pinch of salt! Some kind of plaster like material is probably the best bet... or possibly something a little more exotic like sintered sugar, candyfab style.

Anyway, just pondering and rambling. There are other print quality issues to get out of the way before support material gets any sort of practical development, I imagine.

The problem with support materials is that you have to be able to print over them with hot plastic. That means that the plastic has to slightly adhere to them unless you limit your extruder to trying to print straight lines of plastic over support material. You need to think about candidates in those terms.

... with this in mind i tried LOM-fabbing - [forums.reprap.org].

I want to combine a reprap- and a mill-head for better surface-finishing and extending the possibilities of milling too.

The software will be tricky, but this could bring a practicable solution for dealing with overhangs ...

Viktor