FYI, Some sheets of 1/16" polypropylene were obtained from smallparts.com. (This is very similar or identical to the case plastic used on DLT and other larger tape cartridges.) So far this material is relatively easy to work with.
Plus: 1. Can be cut with a (big) pair of scissors. 2. Can be bent by hand 3. Melting point >130C 4. Can be welded with high temperature hot glue (not verified) 5. Rigid enough for a duct (but not for anything load bearing) Minus: 1. Holds a static charge. (Probably not more than any other plastic though.) 2. Few adhesives stick to it. Generic brown masking tape holds pretty well. Some details I tried bending a sample two ways. First, just putting it on the edge of a desk and then folding it. That worked but it turned white and thinned somewhat at the bend, and it slowly opened back up again from 90 to about 100 degrees. That edge was then melted by gently rubbing it with the barrel of a soldering iron. (Find the point just below where it smokes). After remelting the edge was once again clear and the angle stayed firmly at 90. Another 90 degree bend was made by first heating the flat plastic on both sides with the soldering iron barrel and then bending. That edge turned out a little better, the thickness of the plastic through the turn was very close to that of the flat parts. Hard to get it to just the right temperature though, so there was some smoke. Either method made a good enough 90 degree bend for an air shroud. Finally, I tried gluing two pieces at right angles using a high melt hot glue. The hot glue gun claims to run at 395F, and the glue stick was nothing special, just generic high temperature hot melt. Mixed results. After it cooled and was allowed to set overnight I tried to tear the two pieces apart by hand, pulling in opposite directions, and they held together. However, I was able to snap the pieces apart by folding it at the junction. (Applying quite a lot of torque to the junction.) The glue completely let go of the top of the "T", all of it stayed on the vertical part. At this point it was easy to peel the rest of the glue off. Seems like the bonding was good perpendicular to the surface, but pretty weak parallel to it. If the piece wasn't physically abused it would likely hold together in an air shroud. I had read somewhere that the hot glue melts the polypropylene so that it was effectively a weld, but that is not how it turned out with this glue. Neither piece of plastic was distorted where the glue had been, so clearly not melted. There are specialty hot melts made of polyethylene or polypropylene, and those may actually weld this material. Regards, David Mathog mat...@caltech.edu Manager, Sequence Analysis Facility, Biology Division, Caltech _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
