Hi, When I thought of water soluble support structures (great concept), something made a click. I had the (crazy?) idea of extruding in a liquid (e.g. water, oil). It may sound crazy, but bear with me... I want to try it, but I'm still waiting on parts to start building the RepRap :( Extruding in a fluid has two main implications: 1. Flotation support: If the level of the fluid is controlled, this has the potential to make newly extruded thermoplast float. This would replace the need for a solid support structure. We could dissolve salt in the water to make the water 'heavyer' since some thermoplasts may be slightly heavier than pure water (while many plastics are lighter than 1kg/dm^3). 2. Controlled cooling: The fluid will have better heat conduction than air. This means that if you carefully choose the temperature of the liquid, you will cool it more quickly and only to a desired temperature. This may reduce or eliminate warping. From what I read, it seems that the cooling causes shrinkage. If a layer is kept hot enough the object cooling could be postponed until it's finalized. Then, it can cool as a whole. If we need high temperatures we could use a liquid (oil) with a higher boiling point. We'd have to figure out if the liquid interacts with the plastics (in a good or bad way). Since I cannot try it, anyone, please give it a try! It might be as simple as using a small plastic container and adding x deciliters of water every layer. Eventually it may be hard to perfect this technique, but if it has the potential to improve the product, it is worth giving it a proper try. Please also let me know what you guys think of the idea, and what remarks or alternatives you have! The good thing is: water, oils and salt are universally available. Regards, Erik de Bruijn [blog.erikdebruijn.nl] https://reprap.org/forum/read.php?70,10954,10954#msg-10954 Mon, 09 Mar 2026 14:10:50 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?70,10954,11996#msg-11996 https://reprap.org/forum/read.php?70,10954,11996#msg-11996 Theis Plastic Extruder Working Group Thu, 15 May 2008 05:45:16 -0400 https://reprap.org/forum/read.php?70,10954,11995#msg-11995 https://reprap.org/forum/read.php?70,10954,11995#msg-11995
... as the printed slices acts as thermic isolators, you have to cool the ambient down, so the topmost surface of your printed object is in the right temp-range.

When you print small droplets of water, they cool down very fast and because of the doubled shock when firing out of the nozzle and impacting at the surface i think they didn't stay in the 'supercooled fluid'-phase, so it should be enough when you have something below -6]]> VDX Plastic Extruder Working Group Thu, 15 May 2008 03:35:18 -0400 https://reprap.org/forum/read.php?70,10954,11989#msg-11989 https://reprap.org/forum/read.php?70,10954,11989#msg-11989
My guess is that -10]]> Scorch Plastic Extruder Working Group Wed, 14 May 2008 22:21:30 -0400 https://reprap.org/forum/read.php?70,10954,11962#msg-11962 https://reprap.org/forum/read.php?70,10954,11962#msg-11962
... you need a special setup, where the ink and printer-guts are above 15]]> VDX Plastic Extruder Working Group Wed, 14 May 2008 03:58:39 -0400 https://reprap.org/forum/read.php?70,10954,11954#msg-11954 https://reprap.org/forum/read.php?70,10954,11954#msg-11954 Gene Hacker Plastic Extruder Working Group Tue, 13 May 2008 22:05:12 -0400 https://reprap.org/forum/read.php?70,10954,11952#msg-11952 https://reprap.org/forum/read.php?70,10954,11952#msg-11952
[attachment 732 airborn50.JPG]
(Frozen soap bubble drifting by)

Small quantities of water freeze quickly when it is cold. I think it was between -5 and -10 deg F when I took this picture.

Scorch]]> Scorch Plastic Extruder Working Group Tue, 13 May 2008 21:28:00 -0400 https://reprap.org/forum/read.php?70,10954,11929#msg-11929 https://reprap.org/forum/read.php?70,10954,11929#msg-11929 VDX Plastic Extruder Working Group Tue, 13 May 2008 02:15:30 -0400 https://reprap.org/forum/read.php?70,10954,11928#msg-11928 https://reprap.org/forum/read.php?70,10954,11928#msg-11928 [home.att.net]
[web.mst.edu]

As for printing in liquids, The plastic will only float on the surface if the amount of liquid displaced weighs more than the force applied by the plastic stream from the extruder.]]> Gene Hacker Plastic Extruder Working Group Tue, 13 May 2008 02:07:49 -0400 https://reprap.org/forum/read.php?70,10954,11905#msg-11905 https://reprap.org/forum/read.php?70,10954,11905#msg-11905
Since the density of plastic is so close to water, you really could get away without much support on overhangs. And with a little immersion heater you could control the temperature very accurately. Might make a big difference in warping. You could have a toilet bowl style float valve that kept the water level just below the print head as the Z axis drops. And it would be very easy to keep the working piece at a temperature near it's melting point, without melting the Darwin.]]> Wade Plastic Extruder Working Group Mon, 12 May 2008 13:50:21 -0400 https://reprap.org/forum/read.php?70,10954,11735#msg-11735 https://reprap.org/forum/read.php?70,10954,11735#msg-11735
and even when your design fails you can have fun with liquid nitrogen :D]]> r2kordmaa Plastic Extruder Working Group Tue, 06 May 2008 16:59:48 -0400 https://reprap.org/forum/read.php?70,10954,11708#msg-11708 https://reprap.org/forum/read.php?70,10954,11708#msg-11708
noted your water idea above.

i was thinking of the possibilities of printing upside down.

wasps make very light, strong nests from paper this way.

just a thought.


liked the water idea though.

i wonder if it is possible to print ice. at a low temp, a spray of liquid water should freeze instantly through evaporative cooling.


dunc.]]> duncan Plastic Extruder Working Group Tue, 06 May 2008 03:41:26 -0400 https://reprap.org/forum/read.php?70,10954,11151#msg-11151 https://reprap.org/forum/read.php?70,10954,11151#msg-11151 available for make your own fuel, and in the UK you are allowed to brew up to
2,500l per year without tax. The raw material is cooking oil, either fresh
or used. So we can even be green while reprap-ing!

David]]> davidgoodenough Plastic Extruder Working Group Wed, 16 Apr 2008 17:21:14 -0400 https://reprap.org/forum/read.php?70,10954,11150#msg-11150 https://reprap.org/forum/read.php?70,10954,11150#msg-11150 www.matweb.com] and looked for materials with a melting point below 60C and a density around 1.3 g/cc. Two materials caught my eye:

Sodium acetate trihydride (aka "hot ice"): melting point 58C, density 1.45 g/cc.

Glycerin (aka glycerol): melting point 18C, density 1.26 g/cc.

Both of these are fairly cheap. Glycerin's probably the easiest to handle. Not sure how either of these would affect adhesion.]]> degroof Plastic Extruder Working Group Wed, 16 Apr 2008 14:49:48 -0400 https://reprap.org/forum/read.php?70,10954,11137#msg-11137 https://reprap.org/forum/read.php?70,10954,11137#msg-11137 r2kordmaa Plastic Extruder Working Group Wed, 16 Apr 2008 01:11:28 -0400 https://reprap.org/forum/read.php?70,10954,11079#msg-11079 https://reprap.org/forum/read.php?70,10954,11079#msg-11079 degroof Plastic Extruder Working Group Mon, 14 Apr 2008 13:41:11 -0400 https://reprap.org/forum/read.php?70,10954,11019#msg-11019 https://reprap.org/forum/read.php?70,10954,11019#msg-11019
I'll just give it a go myself when I've built the RepRap. I'll add it to the list of experiments that I intend to do. [offtopic] I'm also going to order Lens alloy or fields metal to try to extrude that. I've got injection needles of which the plastic parts can handle 90'C water at least and the melting point of these metals is below that. The needles are stainless steel so I think they won't dissolve in the alloy.[/offtopic]]]> ErikDeBruijn Plastic Extruder Working Group Sun, 13 Apr 2008 06:58:06 -0400 https://reprap.org/forum/read.php?70,10954,11017#msg-11017 https://reprap.org/forum/read.php?70,10954,11017#msg-11017 r2kordmaa Plastic Extruder Working Group Sun, 13 Apr 2008 06:37:16 -0400 https://reprap.org/forum/read.php?70,10954,11008#msg-11008 https://reprap.org/forum/read.php?70,10954,11008#msg-11008 ronanwarrior Plastic Extruder Working Group Sun, 13 Apr 2008 00:42:24 -0400 https://reprap.org/forum/read.php?70,10954,11002#msg-11002 https://reprap.org/forum/read.php?70,10954,11002#msg-11002 r2kordmaa Plastic Extruder Working Group Sat, 12 Apr 2008 17:30:16 -0400 https://reprap.org/forum/read.php?70,10954,11001#msg-11001 https://reprap.org/forum/read.php?70,10954,11001#msg-11001
... i wouldn't recommend to use fluid metals as support, but you can try with galinstan from [www.geratherm.de] (wikipedia: [en.wikipedia.org] )

I have a small probe, it looks and behaves like mercury, but isnt't toxic and is a bit adhesive to some plastics (PET) ...

Viktor]]> VDX Plastic Extruder Working Group Sat, 12 Apr 2008 17:19:06 -0400 https://reprap.org/forum/read.php?70,10954,10994#msg-10994 https://reprap.org/forum/read.php?70,10954,10994#msg-10994 r2kordmaa Plastic Extruder Working Group Sat, 12 Apr 2008 16:48:25 -0400 https://reprap.org/forum/read.php?70,10954,10993#msg-10993 https://reprap.org/forum/read.php?70,10954,10993#msg-10993 Forrest Higgs Plastic Extruder Working Group Sat, 12 Apr 2008 16:36:32 -0400 https://reprap.org/forum/read.php?70,10954,10988#msg-10988 https://reprap.org/forum/read.php?70,10954,10988#msg-10988 r2kordmaa Plastic Extruder Working Group Sat, 12 Apr 2008 15:36:43 -0400 https://reprap.org/forum/read.php?70,10954,10969#msg-10969 https://reprap.org/forum/read.php?70,10954,10969#msg-10969 redskinsjbs Plastic Extruder Working Group Sat, 12 Apr 2008 00:36:33 -0400 https://reprap.org/forum/read.php?70,10954,10954#msg-10954 https://reprap.org/forum/read.php?70,10954,10954#msg-10954
When I thought of water soluble support structures (great concept), something made a click.

I had the (crazy?) idea of extruding in a liquid (e.g. water, oil). It may sound crazy, but bear with me... I want to try it, but I'm still waiting on parts to start building the RepRap :(

Extruding in a fluid has two main implications:
1. Flotation support: If the level of the fluid is controlled, this has the potential to make newly extruded thermoplast float. This would replace the need for a solid support structure. We could dissolve salt in the water to make the water 'heavyer' since some thermoplasts may be slightly heavier than pure water (while many plastics are lighter than 1kg/dm^3).

2. Controlled cooling: The fluid will have better heat conduction than air. This means that if you carefully choose the temperature of the liquid, you will cool it more quickly and only to a desired temperature. This may reduce or eliminate warping. From what I read, it seems that the cooling causes shrinkage. If a layer is kept hot enough the object cooling could be postponed until it's finalized. Then, it can cool as a whole. If we need high temperatures we could use a liquid (oil) with a higher boiling point. We'd have to figure out if the liquid interacts with the plastics (in a good or bad way).

Since I cannot try it, anyone, please give it a try! It might be as simple as using a small plastic container and adding x deciliters of water every layer. Eventually it may be hard to perfect this technique, but if it has the potential to improve the product, it is worth giving it a proper try.

Please also let me know what you guys think of the idea, and what remarks or alternatives you have!

The good thing is: water, oils and salt are universally available.
Regards,

Erik de Bruijn
[blog.erikdebruijn.nl]]]> ErikDeBruijn Plastic Extruder Working Group Fri, 11 Apr 2008 13:43:55 -0400