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Resin casting

Posted by Omega 
Resin casting
August 01, 2007 11:35AM
Has anyone explored the method of resin casting for depositing thin layers of material?

Thermoplastics are good and cheap but one can avoid the need for melting/heating by using some material which sets as soon as it is mixed with another.

I guess the liquid will stay on the substrate and will not flow away, if deposited in tiny amounts or sprayed. The 'hardener' can then be sprayed on this layer. Or another way is to mix them in a mixer before depositing on the substrate.

So what do you guys think? Is this practical? Any cheap resins having this property are available?

Sorry, if my terminology is off, I'm new to this fabrication thing and I'm planning to build my own fabricator in near future. smiling smiley
Re: Resin casting
August 02, 2007 08:52AM
I suppose Fernando and myself are the current big pushers for thermoset type systems. I am a chemist working with one of the major producers of those types of systems so its what got me involved in reprap in the first place. I have access to literally hundreds of different types and varities of resins. As well as having access to the PhDs that developed them.

I am currently experimenting with a air powered binary gun that injects both resin and hardener at the same time. The problem is that I am concentrating on filled systems since they are FAR cheaper than pure materials but the filler makes the materials very non-newtonian.

Fernando is working on more of what you described but rather than using injected hardener he is experimenting with blocked cataysts and photo-reactive cataysts. Blocked cataysts have a blocking group that prevents that catayst from becoming active until it is heated above a certain tempature so the idea is to hit it with a focus beam of light to flash heat it. Photo-reatives use laser light rather than heat to generate the catalyst.

My paticular work revolves around making molds of the parts rather than the parts themselves. Molds are much faster and potentially allow for very high filler levels with much lower costs. Thats the reason that I need to find a layman friendly way to make at least mockups of the parts. My intent is to then get a set of parts into the hands of our fellow reprapper Englewood since he is a engineer and only an hour drive from me.


The thoughts and ideas expressed in this post do not reflect those of my employer and are intended only as communications between individuals. Any attempts at implement are at your own risk

Edited 1 time(s). Last edit at 09/12/2007 09:12PM by ohiomike.
Re: Resin casting
August 02, 2007 09:45AM
Mike put it very accurately in the previous post.
I have already tested one solution for ultra-violet setting applications. This solution will work for polyester, acrylic and epoxy resins.
I am currently waiting to receive my order for blocked acid catalyst, that will allow to produce a solution to be used with focused visible / laser / infra-red light to heat up and bake the deposited resin or to draw a figure in a vat of resin. We think that this application has a very big potential. It will work for sure with furfural / furfuryl alcohol / phenolic / urea resins as well as epoxys (probably some other types of resins too). Furfural-Phenolic resins are very cheap resins with excellent mechanic and thermic properties (bakelite is one example)

I am not concentrating on molds uniquely but as both you and Mike said, its a great way of building things. One of my imposed requirements is that the resolution of the printing process must allow to be quite accurate (< 0,5mm). Thus the resin mixes i research have to allow for this
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