Thursday, July 21, 2005


Flat structures from EVA

While these glue gun "blobs" aren't too impressive to look at, they illustrate that we can successfully bond layers of EVA:

Keith and I got the final one going this morning, using the winding pulley mechanism shown below. It's not a puddle - it is actually cohesively constructed in a spiral manner. The counterweight is on the end of the white string exiting to the left:

Bear in mind that we are lowering the table manually, and not compensating for the increase in the relative speed of the turntable as the head moves further from the centre. In all, I think we did well !

We've also produced a glue gun Polymorph nozzle that extruded 0.8mm strands of same. Unfortunately it is not practical to use a standard glue gun mechanism or the systems I currently have here to push Polymorph through at any useful rate. We're experimenting with wider nozzles, and we'll widen it until we get one that works.

We've also put a proper power switch on the RepRap, so I don't leave it powered on at night - the cats might spark it up.

Vik :v)

Okay. I've been watching your blog for a few weeks now and throwing in the odd comment for the past few days. If I could, I would like to clear up some confusion that I have about your replicator project.

What you are doing reminds me of some work I did just a few years ago with some very different goals in mind. I went through many of the same steps that you outline in your blog, though I hadn't got as far as you have when I got drawn back into my responsibilities in my consulting practice.

First off, I gather from comments and pics elsewhere on this site that you have quite a decent prototyping machine at your disposal. It's one that I would have given my left arm to have had access to.

Given that, why are you not using it to create your replicator? You're using Meccano and bits that your liberated from various places, an approach that reminds me a lot of the one I took. :-) It would seem to me, however, that it would be a lot easier to work back from your protyping machine to something that used the same prototyping materials that it does, but which is mostly self-replicable. From there it would seem more straightforward to explore new thermoplastics and recycling approaches.

Obviously, you had some good reason why you didn't do that. Could you share what that reason was with me? :-)
Okay, I think I just answered my own question. Vic is in kiwiland and Adrian is at Bath. That does pose a few problems. :-(
It's a little deeper than that. I'm using a lot of Polymorph in the construction of my device, which is a construction material that we need to test. It's probably not ideal, but is relatively easy to develop prototypes with.

Also, I have already determined that I can readily replace Meccano parts with FDM'd artifacts. As Meccano is quite easy to get hold of and doesn't require fabrication time, I tend to use it more often. There are some FDM'd parts being used with Meccano, and that proportion will increase.

One of the good things about developing this way is that we are discovering what components are available on opposite sides of the world. If we find that we require a component that isn't available in New Zealand, for example, we know it is a bad idea to include that mechanism in the design.

Don't forget that this device has to be capable of being produced everywhere from Afghanistan to Zaire. This results in a distinct Heath Robinson/Rube Goldberg flavour to some parts :)

Vik :v)
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