Thursday, August 30, 2007


RepRaps by the ton II

I have now built Nishad's resin-moulded extruder parts (blog 24 August) into an extruder, fitted it in Darwin (thanks to the Really Useful new plug-in extruder swapper), and tested it.

It works perfectly :-)

This gives us a way to make lots of extruder kits for people quickly. Zach is already sorting this out for the RepRap Research Foundation Online Shop. Watch that window!

Tuesday, August 28, 2007


RepRap progress is faster than a speeding bullet

At the suggestion of a RepRap website fan I have put together a wiki page showing key items made (almost all by the tireless Vik) as the project has progressed.

The first thing we ever made was just over a year ago. In that intervening year progress has been very rapid indeed, as you can see when it is all gathered together in one place at...

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Saturday, August 25, 2007


Honey! I replicated the cat!

No, not a Catfab 4000, but a humble Darwin taking shape in New Zealand as it is at time of posting - and, of course the ginger cream Burmese 'Chad', who is kindly demonstrating what I have to put up with in my workshop. Thought some readers of the blog might like to know I'm now employed by Catalyst IT, stauch supporters of Open Source in New Zealand, who have kindly made it possible for me to work one day a week on RepRap.

Vik :v)

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Friday, August 24, 2007


RepRaps by the ton

We (and especially Zach) have been devoting quite a bit of thought to how to get people started with RepRaps - when a lot of people have them, then they can all make parts for each other, but when hardly anyone has them then they can't.

In Bath we've had a visiting student over the summer: Nishad Sohoni. He has really come up with something special. Here are the parts for the standard RepRap polymer extruder (quick-swap version) stuck to some sticky tape:

The sticky tape will form a mould split line. Here are the same parts in a box with some risers and runners added:

And here's what you get when you pour silicone rubber in under a vacuum (to eliminate bubbles):

Then Nishad cut the silicone to the split line with a scalpel and took the original parts out:

Note the use of a few silver steel rods as cores for deep through-holes in the parts to be made.

Then he put the mould back together with a load of elastic bands and poured in a resin (no vacuum - the resin stays liquid enough for the bubbles to float out of the risers before it sets). The resin we used was the "water-clear polyester casting resin" from e-bay here. Here is the result:

We're obviously going to make it into an extruder and test it...

The neat thing about this process is that, while you need a vacuum chamber to make the original mould, the making of the actual parts can be done in ordinary (well ventilated...) conditions. So we can make moulds and send them to people, who can then make kits for the RepRap store (or elsewhere).

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Tuesday, August 14, 2007


Aluminum Extruder Sneak Peek

If you've followed along in the forums, you know that we have someone CNCing us 10 extruder kits from aluminum. They should be finished shortly, which is very exciting. It will be a big step for the project as a whole to double the number of RepRap extruders that are 'in the wild'.

In the pictures here, I'm assembling a prototype of the extruder. The finished version will only be slightly different, if at all. This extruder feels very strong, and I think once we get these into the hands of some very capable reprappers, we will see some very good, and very exciting results come about.

More pics on Flickr.


Tuesday, August 07, 2007


Quick change artist

My MSc student Arman has modified his auto-head-changer (which always was for Mendel, not Darwin) to design and make a quick-change plug-unplug mechanism for the Darwin head. You have to take the head off quite often when you're setting up the machine, and also when you're using it. Before, that took about 15 minutes of fiddling with cap screws in hard-to-get-at places. Now it takes a couple of seconds.

The next thing we'll do is to make two heads: one for CAPA and one for HDPE so we can swap them ad-lib for experiments. We'll also put the balloon paste extruder on the same mechanism next to this one for support experiments.

I'm not sure if we want to change the Darwin design at this late stage, but this certainly makes things easy...


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