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Conundrum

Tue May 31 2011, 05:34PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Hi all.

Seems that mixing Polymorph (aka Polycaprolactone) with acetone and then printing the resulting mixture with a one nozzle print head made of a pair of opposed piezo disk speakers and Epoxy casing could allow a really really cheap 3-D prototyping machine to be built.

Turns out that people have been aware of this for a while but no-one knew how to make it "print" easily.
The DIY print head is the required secret sauce.

No this won't work with an Epson (tm) head, the acetone will turn it into foul smelling goo with wires sticking out.

Comments?

-A

"Bother!" said Pooh, as his 32GB microSD turned out to be a fake...

Pinky's Brain

Sun Jun 05 2011, 06:30AM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
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How would you get it to solidify correctly and fast enough?

Conundrum

Mon Jun 06 2011, 07:59AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Applied heat would do it, my suggestion is to use a modified Mendel which moves the workpiece rather than the print head.

Ought to work, once the solvent has evaporated which (I tried it) takes about five seconds with the mixture I used of 75g acetone 15g polymorph and 0.5g strontium aluminate it sets just like normal Polymorph.

To make it requires a hot water bath to encourage full mixture of the components, or if you are a mad scientist like me 10 seconds in the microwave

*DO NOT* do this, use a water bath, kthx.

I used a surplus glass bottle which originally contained an acetone-alcohol mixture so the lid should be able to last.

It occurs to me that the technique should also work with other chemicals such as iron particles for making DIY inductors, or EL phosphor for making flexible EL sheet without the usual hassles.
I expect that coating the plastic with ITO then a protective flexible layer should work.

Did you know that a broken LiFePO4 battery has about 4 feet of copper sheet inside suitable for such experiments? I sure didn't.

Wonder if I could sell this for coating fishing floats or something? I'd used conventional Polymorph mixed by hand with aluminate but this stuff seems far superior and potentially easier to coat onto any compatible surface.

-A

Pinky's Brain

Mon Jun 06 2011, 09:42AM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
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Posts: 837

I don't see how the droplet would maintain shape during hardening. With the normal application the heated plastic stays together out of sheer viscosity, yours would just splatter all over the work piece AFAICS.

Conundrum

Mon Jun 06 2011, 01:47PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Will have to try it and get back to you.

From the looks of it a gradient heated print head may get around this, as the solvent would flash boil during extrusion.
I may need to use a Peltier somewhere to keep the rest of the plastic at its liquidus temperature.

-A

Shrad

Tue Jun 07 2011, 01:56PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
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Posts: 780

you could use a laser diode focused to the needle point and send a quick light pulse to cure it

but will it cure with 405nm? the main advantage is the focal point you could achieve, less than 100Âµm is easy

Pinky's Brain

Tue Jun 07 2011, 05:49PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837

These guys get OMFG good resolution with inkjet in 3D ...

If you put down support and white material first as a sort of mold you could use a low viscosity transparent UV resin together with a colour inkjet printer to create full colour objects (the low viscosity resin would go in between the support and the white material, and mix with with ink before curing).

Conundrum

Tue Jun 07 2011, 11:14PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Interesting.

I had the intriguing idea of using microcrystals of silicon carbide distributed through a somewhat conductive matrix to make primitive semiconductors, using a high voltage to align the crystals during curing.

Sound possible?
the same method has been used to "burn out" carbon nanotubes which are conductive rather than semiconductive so that the properties can be controlled.

-A

Pinky's Brain

Wed Jun 08 2011, 01:00PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
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Posts: 837

I think it would be extremely leaky ...

To get back to DIY inkjet printheads ... how about simply doing a HV discharge in the inkchannel?

Conundrum

Wed Jun 08 2011, 06:43PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Yep that ought to work.

Wonder if EPE would publish this as an article if I get repeatable results?
-A

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