I've read a little bit here and there about plans for being able to use support materials, the lack of this feature being (in my opinion) one of RepRap's biggest limitations. There are obviously two halves to this, the first being the extruder for the material, and the second being the material itself. I'm just starting to get the parts for my own RepRap now, so the extruder half is totally over my head.

As far as the material though, a lot of people are talking about mixed pastes and powders, but these seem unintuitive to me. What about sugar? Sugar dissolves fairly easily in water, and it melts as well. I haven't tried it, but if it's as simple as melting it down, extruding it, letting it solidify, and then dissolving it later, it seems like a simple choice.

My second idea is anything that melts more easily than the main plastic. You could simply melt the support material off of the plastic in the end, couldn't you? The main advantage I see to this is that you could use something that comes in filament form and use very similar extruders. In other words, the reprap could be designed to work with multiple arbitrary filament-based materials, one of which happens to be intended to be melted off in the long run.

What kind of support materials to commercial machines use? This page implies that they use gels:
http://www.objet.com/Materials/FullCure_Materials/

I haven't even started to assemble my reprap yet, so I may be ignorantly wasting everyone's time with these ideas. I apologize in advance if such is the case!

-Hypoon

Interesting idea, using sugar.

I once thought that simple flour and water could also work as a support material, though it may need an external container around the part being built.

As for using pastes, MakerBot already has a syringe attachment designed.

There is also the other 3D printer project called Fab@Home

After doing some more googling, it seems that some people have already had success using icing sugar (it washes away easily). As far as straight sugar is concerned, caramelizing might be a problem. For simplicity's sake, I think solids that could be pulled into filaments would be easier to work with. Unlike powders, they don't pose danger to RepRap's moving parts, and unlike pastes, they're not messy.

Once I get my own RepRap built, I'll look into extrusion techniques. After doing more research, I realize that although there are many materials that would be awesome support structures, not all of them can be extruded easily. The trick is of course to find a pair of extruder and material that work together nicely. I'll keep thinking.

-Hypoon

Hey, this seems nice idea; then you could print a cup upside down filled with sugar! ;-)

Seriously, actually an interesting idea. Something like this could be very usefull; material which everybody gets easily and is cheap.

Personally, I think missing support for support material is the major disadvantage of RepRap. This problem should be solved as soon as possible. I have not yet started to make my own, still considering..

About the support material; how about silicone? The one you use on your bathroom? Maybe it could be extracted simle by using just a string to generate constant force for the syringe and the a valve to extract or stop extracting?

How about using the same material which is used for printing, but add some substance to change it somehow? For example, if we could get ABS to crack in to powder when freezed, if added some other material? hmm.. that would anyhow need another extruder..

How are the several extruders made? Just two extrudes near each other and then shifted x or y to the active extruder? Or is there actual extruder change?

I bet we could find a few things in here handbook of water soluble polymers
I know that PVA polyvinylalcohol (basically elmer's glue without water ) is soluble when heated in water above 80C so boiling water may work and it is a rather robust polymer. We use PVA as a water soluble binder for our ceramic spray drying formulations at my workplace.

Edited 1 time(s). Last edit at 02/09/2010 12:13PM by jabberwocky.

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[thejabberwockyandthejubjubbird.blogspot.com]

May be EVA could be a choice- It is the common hot melt glue that melts at lower temperatures and extrudes easily and can be a good binder and strong material..
It can be extruded as a filament and can be used as build support material as well can be easily blended with other polymers. It has relatively low melting point.
Thanks
JAGS

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JAGS
DESIGN FOR A CHANGE!

I just bought a used Stratasys FDM 1600, which dates back to before they started using soluble support material - instead it uses a 'breakaway support system' (BASS) with a material that is peeled or broken off of the ABS. I did a small test piece, and the support material seems to do quite well - once cool, you can carefully peel the raft off the bottom of the part. According to the MSDS sheets I dug up on the support material, it is simply HIPS (high impact polystyrene).

Quote
nite69
I think missing support for support material is the major disadvantage of RepRap

What leads you to that conclusion? How much RP printing have you done? How many objects have you designed that are completely impractical to print on a RepRap until you have working support material extrusion? Do you have a collection of these online somewhere? My sense is that in practice, you can print a remarkable number of objects without needing support extrusion. See http://www.thingiverse.com/thing:2437 for one interesting test example (not my creation; I think it is indicative of what careful thought and a single extruder can do).

I think adding support extrusion is a great idea, and in time it will arrive; there has been some level of software support for it in the reprap host software for a long time now. It is an interesting research area for people to be working in.

However, I'm not at all sure that its lack is "the major disadvantage" of RepRap at the moment. What about print speed, ease of RepRap construction and calibration, ease of use once calibrated, ease of device transport, hot ends that clog or back up more often that one might like, etc.? Are some of these not more of a current practical limitation to RepRap reproduction and proliferation than lack of support material extrusion, for many possible users and uses of RepRap?

RepRap in its current state has many areas where improvements are clearly desirable. In a sense, that's the whole point of the self-replicating, fully open, evolutionary design concepts that are at the heart of what RepRap is all about -- people can improve it, and give back their design improvements to the RepRap community.

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Jonathan

However, I'm not at all sure that its lack is "the major disadvantage" of RepRap at the moment.

People have different priorities. I'd find it very useful for some of my projects, like figurative sculpture.

It is much more fun to discuss and advance a particular feature set than to try to argue comparative worth of different feature sets, like print speed versus support material, or print speed versus the ability to function as a cnc router, which turns into a sort of "beauty contest".

We're basically comparing mopeds, ferraris, and long-distance trucks here.

Has anyone tried feeding HIPS or EVA into a RepRap extruder?

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

The stratasys Vantage SE machines use a soluble support that is in a spool of filament form and is then extruded at around 215 C. It is then disolved in hot soapy water at around 70 C. Not too sure what it is made of however. Perhaps we could find out and make our own of this?

... i have some printed parts made of the brownisch/translucent startasys support material - it seems to be a sort of sugar with long molecules, so it doesn't taste sweet ... but is meltable, solveable and stable enough to act as support for the molten (heat) fabbing material ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Before I got my HBP I have printed ABS on a platform of melted sugar.
What i did was melt powdered sugar in a metal ladle over a stove and pour it onto an aluminum platform, squishing the molten sugar down from above with a sheet of stainless supported by a cutting board. coins in the four corners made the sugar platform level.

It worked, except larger parts would warp and the melted sugar would often times crack and detach from the platform. I haven't tried it on my HBP and without having a sugar extruder I can't try to intersperse sugar and plastic layers to use it as support. But I think the technique definately has promise. Now we just need to make a sugar granule extruder, which I think would be REALLY awesome to have.

Hello,

Do you have any advance in this topic?

Someone have achieved to have a working soluble support material?

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Ernesto Pareja

dcctrains.netne.net

im new to this, but i saw on ebay 25lbs of hot melt glue for around 80 bucks, could you not just take a hot glue gun, reduce the nozzle size, and add a wades extruder with a big hobbed gear to it, and use it as a seperate extruder for support material. then to remove the hot meld glue i think you could just stick it in the freezer and snap it off, and if you lower the temperature of the nozzle, the bond strength would go down, making it easier to break away. [www.ebay.com]

I'm sure this has been thought of before but I haven't seen it anywhere - how about using the same material as the print for the support material but adding a thin layer of something between the support and the printed object to make it easy to separate. This would have the advantage that the support material would behave the same as the material in the object (expansion etc) and since a lot of the alternates seem expensive (PVA etc) it may well be a reasonably cheap option.

Adrian Bowyer experimented with this over two years ago with some success.
See the RepRap: Blog: Overhang support and PCBs.

Edited 1 time(s). Last edit at 09/18/2012 07:52AM by rhmorrison.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

I have been thinking of an extruder which prints ABS filament, but also drags in a surrounding powder into the mix. Plastics are often incorporated with a filler, such as glass powder, or graphite etc. either for strength,cheapness or colour.

The reason I mention this here is that you could print the main part with a say 20% mix of the additive for a strong part, but print the support material with say 90% additive making it brittle or soft. The extruder head would have two motors, one for ABS filament, one for applying the powder pressure on the outside of the molten filament pool.

This sounds a bit obscure, but there are several Rapid prototype machines at my works that print solid and rubber parts in one piece (For example a gear stick (stick shift) with combined rubber gaiter). You can adjust the print mix to set the shore hardness of each area of the part.