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Print Filler Material?

Posted by WDZaphod 
Print Filler Material?
March 20, 2012 11:18AM
Hi Forum,

currently I am building my 1st Printer (Mendel), so no experience yet.
Just thinking of something - maybe it's possible?
The Idea is to print a 2nd Filler material to support 90° (free air) printing. Like filling up a box with Something (tm) to support the upper layer. The interesting point is: How do I remove this filler?
Use something like sugar, and you can simply wash it out. Or something what melts at less then 100°C, and you can boil it out in water. (Wax, Chocolate?)
Any idea, if this already exists, or what kind of material you can use in a standard extruder?

Can't wait to start :-)

regards from Switzerland,
Re: Print Filler Material?
March 20, 2012 06:50PM
This idea is substantially older than reprap itself. It may well be as old as FDM.

I think the current best material is PolyVinyl Alcohol, a plastic related to PVA glue you probably remember from school. It can be printed in a standard reprap extruder, it dissolves in water and there have been successful prints using it, including a functional set of enclosed gears. You'll also need a dual extruder reprap. Makergear sell PVA filament, I don't know if there are other suppliers.

Another plan is to use PLA as support for ABS or vice versa. With appropriate choice of solvents, you can dissolve one plastic and leave the other untouched. Tends to involve fairly unpleasant chemicals. Again, a dual head reprap would be needed.

Yet another plan is to use the plastic as its own support by preventing two layers form fusing strongly. Nophead did some work involving using oil between support and object layers, I don't know if he developed it beyond painting it on manually at the appropriate time.
Re: Print Filler Material?
March 20, 2012 08:07PM

Me and the rest of my group from university experimented with gelatine as a build material. It dissolves in warm water and I think would potentially make a great support material.

Please see the attached link for examples of the material we experimented with and our Lego repstrap:

Any questions please email me as I would love to develop a way of getting this material to be useable as a support material for all reprappers to use.
Re: Print Filler Material?
March 21, 2012 01:17AM
gelatine, i never gave much thought to that one, i wonder how well it would deal with pla touching it, would it just melt away.?

and how would you make it a little stiffer to support at least a little wight. its a good idea i think it would be worth looking into.

Re: Print Filler Material?
March 21, 2012 03:47AM
You make a few very good points. I remember that over time it dired out and went very strong. It may be possible to mix it at a higher quantity of gelatine to water so you can dry it fast enough for it to turn hard.

Our samples were very rigid in the end - not what you would expect from gelatine. In the end they were going reasonably birttle. They also adhered well to very smooth surfaces. We had one sample stuck to a glass window and it stuck like glue. Had to be scraped off in the end.

I am not sure how it would deal with the PLA touching it. I think as long as the layers you were building were thin enough (thin enough that there was not much weight being applied to the layer below) then it might be alright as the gelatine would have sufficient time to cure between layers.

Another idea i have is to have the gelatine running through a hot tip (separate extruder to the PLA/ABS) and then cooling it as it comes out. This may assist with stengthening it as it comes out. Negatives here means more parts neccesary for extruder and also might cause warping to the PLA/ABS.

What are your thoughts on this?
Re: Print Filler Material?
March 21, 2012 04:07AM
Gelantine is weird - for me it's something slobby like a Jellyfish, or harder and unbelievable glue-crab like a hot Haribo.
So - as a result of my question: People tried already in different ways, but it's not working, too complicated, or simply not needed?
Re: Print Filler Material?
March 21, 2012 04:31AM
I can agree that gelatine can be a difficult material to work with. However, once you know the correct gelatine to water ratios and melting temp it can be controlled very well. I can't see how it is not working or too complicated. It is able to be built into 3d form and hold it's shape and this has already been proven. It is also only a two part mix which is fairly simple I would have thought.

Maybe I am wrong about gelatine as being an appropriate support material. I do know that it makes a great build material for making beautiul structures out of though.
Re: Print Filler Material?
March 21, 2012 04:51AM
Support structures have to more than support the plastic against gravity. They need to have the same properties as the bed surface. I.e. the plastic has to stick to it and be held down against the warping forces.

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