glassblowing and joint sweating

Glassblowing is necessary from time to time in order to fix something you just broke, make a piece of glassware which you need right now, and so forth. Our glassblower arrives biweekly, so if you want something done by him it usually takes a long time, which could be remedied if the physics shop (which houses the glassworks) would just let us use the damn annealing oven.

We needed a piece of tube with a 3/8th inch outer diameter attached to a length of 1 inch tube with a standard taper 24/40 joint. This is nothing more than a tube, attaching one end straight on to the other. I tried for some time to make the first attachment to no avail. I could get as far as blowing out the end of the tube to make an even edge, but I was completely inept at attaching the two pieces. After several poor attempts Professor Heller learned of what I was doing, and although he thought it was admirable, was quick to point out exactly where I was failing.

I was missing a swivel joint used so that you could blow into a tube connected to the end of the glass and spin it at the same time. I distinctly remember that the last time I watched Heller connect two tubes together he did it without the aid of the swivel joint and did just fine. Apparently he was just showing off.

Hand annealing is another issue entirely, as Heller doesn't seem to have the patience to do it properly and as stated earlier, the physics shop doesn't let us use the oven. So even though the piece has been made it still can't be used because its too brittle in the present form.

On a similar note, sweating a joint in copper tubing was also on the day's chore list. I've seen my father and grandfather do it several times. The made it look ridiculously easy, just polish, flux, and sweat. This is a lot easier if you remember that you need the flux, which I forgot about on the first several attempts. I read on line that if you were doing this on household plumbing the best way to keep the water out is to jam a wad of white bread into the pipe before you sweat the joint, then just flush it out after you're done.

Curiously enough chemical stores does not stock white bread.