Robot Arm printing a chair

This project is not new ( [vimeo.com] more than a year ago), but I viewed a new one recently (from december) : [vimeo.com]

(since I seen a very small fanuc arm in a lab, I want one to put an extruder on it )

Also interesting for those who work on granule extruders (use existing plastic injection machines)

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The thing I don't understand in the video is when he puts his finger on the molten plastic to push it down. Presumably fridges are made from ABS or PS so I would have thought it was way too hot to touch when molten.

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[www.hydraraptor.blogspot.com]

I don't think that was molten plastic at that point, it was plastic chips in water.
The cleaning process after the first shredding I think...

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

At the beginning of the extrusion he pressed the start down with his finger and does the same with the peak left at the end. The plastic is still very soft but it does not burn him. How?

Edited 2 time(s). Last edit at 04/15/2012 01:17PM by nophead.

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[www.hydraraptor.blogspot.com]

nophead Wrote:
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> At the beginning of the extrusion he pressed the
> start down with his finger and does the same with
> peak left at the end. The plastic is still very
> soft but it does not burn him. How?

Many years ago when I was a young physics tech, my old boss Wally, used to brush molten borax off of silver soldered joints with his thumb. I was impressed but not inspired to try it myself, I knew him for many years and can state with some certainty that his thumb was a genuine thumb and still in working order many years later.
He's no longer around so I'm unable to ask what his secret was.

T Case

This is brilliant.

I'd love to get hold of an STL of that chair to print on a Mendel (as a gimmick).

I also have an Armdroid robot arm (I refer to it in this blog post, but no pictures).

I used a lab arm like this during my final year project at Uni, so when I was offered one I snapped it up. ( it had been used in a lab and when the lab shut this lady took it home and it sat in her loft for years - it has a printed label with the name "Ron" on it.)

I still need to get it running as It was designed to run with a BBC micro which I don't have. I figured I might be able to learn about the electronics as part of the RepRap community and then make something work. It has a quite a number of axes and the steppers are 6 wire ones, so much to figure out.

Having seen this, a bowden based extruder mounted on Ron would be a nice gimmick!!!

Craig

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[blogger.kritzinger.net]

Quote
nophead
The plastic is still very soft but it does not burn him. How?

Not sure, but maybe like to extinguish candles, he licked his finger before ? He also push it quickly in three times.

Now someone just needs to take a super armatron and build a mini version of this.

I am quite new here, and I have not even started on my 3D printer yet.

Any how, how is it possible to print this big object without a heated chamber?
As Nophead pointed out earlier, it is presumably ABS or PS. I look in my own fridge, and that is PS plastic. When I look it up on Internet it seems to shrink about the same as ABS, but it seems that it can melt between 70—115 ºC (different versions of PS?).
When you look at the video it seems as the layers are still soft several layers down. Is it the combination of printing with really big diameter of molten plastic that keeps the heat, and possibly a low melting point (70ºC), that makes it possible?

As a craftsman your skin on your fingers gets thicker from work. I dont think that this is a big mistery. He might also have wetted his fingers before touching the plastic. If I use my heatgun sometimes I touch the hot plastic. Sometimes it burns me sometimes not. If it does not stick to your skin it wont do much harm ( but dont try this out with any hot plastic!).