Hand machined mechanical pencils

Quartz tubing from a bulb (31/08/13)

I needed some short pieces of quartz tubing (all right, fused silica) and realised I could get them from a tungsten-halogen bulb.

This particular bulb was advertised on EBay as "Philips Plusline Halogen 240V Large 1500W" and was around £6. Here's the datasheet from Philips. It claims the tube is size T4, or 0.434"/11mm, but the actual tube dimensions are 9.9mm OD, 7.3mm ID. The overall length of the bulb iss 254mm. Product ordering code is 055996, barcode 8711500055996

Procedure (I used my little diamond saw): Cut off the evacuation nipple in the center of the tube (unless you want to keep the tube intact as a longer piece). Cut off one end and snip filament. Cut off other end and withdraw filament - keep because it looks cool. Cut right through the middle (where the evacuation nipple was) and then trim each tube to length.

I was able to get two pieces - 87mm and 90mm long. The filament is around 0.2mm diameter. If you left the nipple intact, you could get a 19cm length of tubing overall.

Note: I only did this because I found it impossible to buy a length of quartz tubing at any reasonable price. If you live in a civilized country (i.e. the USA), then it's quite easy to source single tubes at very low cost: