Friday, December 09, 2005
I got the STL parts for Knewt's head this week. As luck would have it, two of them on the same day. Stuart Rolf prepared the STL file and Ken Apple ran the job in Dekalb Tech's CAD lab. Barry Smith of DrafTech provided a head and a great poster that's in the next photo. Thanks a million everybody. (this is a perfect opportunity to use the colloquial "y'all", and even "all y'all" in this particular case").
Barry Smith gave a bottle of "Ambroid Pro Weld" to repair and strengthen the parts. These particular ABS plastic STL models are held togeather by a slight fusing of a .013 bead of melted plastic. These small threads can be torn away from the part if you try, or if it takes a bad fall. Considering how much Knewt falls, that's bad. But by saturating the part with the plastic welder, the fibers are much more strongly fused togeather and become almost as strong as a single piece extrusion. I coated both heads with it inside and out and didn't even use 1/4oz. It's like water and doesn't smell "too" bad.
After brushing the part with this stuff, it becomes shiny. A new advisor to the project, Scott Washington, recommended a filler paste and sanding to cover the texture left by the machine. I tried this and it worked quite well. Lots of had sanding is required. The grits I used were, 150, 220, 320, 600. The errors I made were to leave small gaps in the sanding putty. These were most evident on the vent slots on the top of the head. So I sanded and painted it again. I think by the third time I paint this head, I'll be up to amature status.