Sunday, July 09, 2006


Printing a real part

So I had to cap Ed's Z-axis, Adrian's peristaltic prototyped polyfilla pumper, and Forrest's working opto interrupt. It was tough. May I present my first attempt at printing a bona fide RepRap component, the 6mm stage linkage (known as a "gripley" locally, in honour of Terry Pratchett):

For those who suffer more delusions of grandeur than I, the top one was made by a Stratasys from ABS and I did the skeletal one from Polymorph (must've rolled a metre of it so far today). The bottom part was extruded using the Da Witch prototype. The extrusion was made using a 0.8mm nozzle at 80C, fan-cooled by manual intermittent fan operation. The deposition was halted at 3mm, and the wall thickness is a very constant 1.0mm - at long bleedin' last!

The deposition surface was a cheap Vietnamese wooden chopping board (NZ$3, The Warehouse), from which I had sanded off the varnish. I knew all that sandpaper would come in handy :) The old varnish, whatever it was, stuck to the polymer like glue. This might be useful, and I might get some cheap spray-on varnishes to experiment with as a light spraying on glass may provide enough adhesion. The adhesion to the base wasn't what I'd call excellent, but it was a freshly-sanded surface and some dust may have been present. We'll see how it goes; it'd rather steer clear of wood due to its tendency to warp.

Please excuse the tatty and somewhat sparse infill, but this is only the second complex object ever to have been printed and the filling algorithm needs a bit of tweaking. Nevertheless, I'm really happy with this lot. It shows we're definitely on the right track.

I suspect we may be able to make depositions like these using a ducted fan for continuous cooling. There is still lots of experimenting ahead. But time to sit back with a Cointreau & vodka, and relax for the evening I think.

Vik :v)

Vik! You're making clothes pegs! :-D

Hairspray (if they even still make it) is about the cheapest varnish you can get. Bet you that it will work. :-)
Bet you it doesn't :)

Already tried it y'see.

Vik :v)
LOL! Well done! :-D
When Vik makes the first functioning bit of a RepRap machine using his RepRap machine a little celebration is in order, I think.

Vik - can you point me at the STL and I'll look at the infill problem.
***When Vik makes the first functioning bit of a RepRap machine using his RepRap machine a little celebration is in order, I think.***

Make that a LARGE celebration. That will be a major milestone in the effort. Look like he's getting there pretty quick, too. :-)
The part is here:

Vik :v)
It would be more useful if you'd point us at an .aoi file.
this printed part looks good! keep up the good work on the universal assembler :) I also like the blog...thanks fo documenting the progress with so many blog entries!
The AoI file is the one on but I don't think it's right up to date and there's a lot more stuff going on in that file than just the linkage.

I'll check to see what is up to date and make sure it gets on the site. Meanwhiles, the linkage that's in there should be good enough to get started on.

Besides, the fill algorithm works off STL files.

Vik :v)

Vik :v)
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Nice one Vik,

Seeing as it's the borders which define the quality of the part in terms of fit and all that, I'd say that's (without using expletives) rather good!
For the slipping problem: How about starting with a surface that slippery (glass or something) - but with small holes drilled in it on a regular grid.

You could start the 3D print run by filling in some of those holes with plastic as anchors beneath the bottom layer of the actual object. Then you could replicate the object on top of those anchors.

At the end of the run, the object could be lifted vertically off of the glass and the anchor 'pins' could be trimmed off with a knife.
3d geek, I LIKE it! Fiendishly ingenious, yet simple and elegant.
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