Broken glass or pyrex? CO2 laser source build moving forward

[GregR]

In a first attempt to build a 55 watt slow flow CO2 laser using the pdf kit plan circulated on the internet. A variety of prices for the outer shell glass came in, and the low cost supplier had a heck of time drilling the holes in the pyrex and in the end, only supplied two instead of thee--I try to order extras because in my world there are many quality problems.

How can I tell if the material supplied is actually pyrex and not glass substituted for pyrex? (I am in China and cheating runs rampant). What is the best way to drill glass and not have it break?

One of three outer tubes is damaged




Two outer tubes are good, and the inside tube for the gas (neon glass) is shown below. They have been thoroughly washed with soapy water and rinsed (using our city water), and dried using clean room wipes (no lint). Is this really clean enough? Next step is the glue, so no turning back.

[mixedgas]

You do not normally drill glass tubing without annealing it afterwords. That is why your tubing broke. The normal alternative is to take a pin-point torch and blow a bubble in the tubing. Then strike the bubble off with a sharp file, and flame melt the edges of the hole to both anneal them and clean them up using surface tension. You need a competent glassblower. China is loaded with them.

After soap and water one can bake the tubing using an oven or gentle, even use of a propane torch. The idea is to burn off organics. The correct temperature is obtained when a piece of newsprint placed against the tubing turns light brown. If you use a torch you need to be careful of overheating the leaded neon glass. In lead glass, the incorrect heating regime can cause stresses to form in the glass or turn it black by releasing oxidized lead to the surface.

Steve