AMATEUR VACUUM TUBE MAKING
TORCHES USED IN TUBE MAKING
This is the National type 3A hand blow pipe. Of all the available torches for glass blowing, this is one of the best and cheapest. They are available for about 100 U.S.D. from Mountain Glass. Mountain glass also carries a fairly wide selection of tips for the torch.
This is the hand torch I recommend for the basic glass operations used in tube making.
This torch was originally designed to operate on air-gas so the openings in the valves are quite large. This causes the adjustments to be somewhat critical on small tip sizes when using oxygen-gas mixtures, but the torch is completely useable and practical.
When doing the glasswork, it is many times necessary to change tip types on the torch. This in many cases must be done while the torch tip is hot. The National tips screw onto the top of the torch pipe. Thus to change the tip, you either must wait for it to cool or use a pliers or insulated glove to unscrew the tip. (you could have a can of water nearby to quench the hot tip in so you can change it, but that is not ideal)
This problem can be solved easily and elegantly by changing the way the tips connect to the torch.
Note that on this torch the original pipe has been replaced by a Swagelok quick change fitting. This allows tips to be changed out quickly and while the tip is still hot. Also, it allows using self-designed tips that are not available from commercial companies to fit the original pipe.
The original pipe (made of brass) is cut off just above the low end connection. The Swagelok male connector is machined to press fit into the end of the pipe. You now can use common Swagelok (or the consumer equivalent from the hardware store) to make up as many different torch pipes as you want. The connectors can be the professional Swagelok stainless steel type shown, or the low cost brass consumer equivalents. The consumer equivalents interchange directly with the Swagelok and work just fine. I use both, depending on what I have on hand.
Here is a small homeade torch. The brass body is 1 inch in diameter, made from a section of brass bar. The two valves are small needle valves available at most hardware stores or on ebay. The needle valves are silver soldered to the body. (they could be soft soldered just as well if you don't have capability to do silver soldering) The entire torch can be made using a drill press and hack saw. Cost is about $20 for all the parts.
The torch pipe fitting is a Swagelok quick connect like was used on the National torch, but is a smaller size. (for 1/8 inch tubing) This torch is used for the needle point flame tips so that the adjustment is not as critical. The Swagelok fitting was used because it was on hand, but the consumer brass equivalent version of the fitting available at most hardware stores will work just as well. See the plans section on this site for plans to make this torch.
TORCH TIPS FOR THE TORCH HANDLES
Here we have a group of tips that are made for the two handles shown above. All are homeade and can be made with minimal machine work. Access to a metal lathe is best of course.
1 is a large rosebud tip. 2 and 3 are smaller versions. They are homeade from brass bar stock.
4, 5, and 6 are micro point tips. 4 gives flame diameter of about 1/16 inch. 5 gives a flame 1/8 inch. 6 gives a flame 3/16 inch. These are used for sealing seams in the tube envelope and for general glasswork on small parts.
7 is a "crossfire" torch that has two flames that blow towards a common point from opposite directions. It is used to heat sections where the whole diameter must be simultaneously heated, such as when making a pinch seal.
The second picture is a closeup of the business end of the rosebud torches. The large tip uses 15 liters per minute of oxygen!
The length of the torches from the Swagelok fitting to the top is about 5 inches.
These are the torches that are always used in tube making so you should plan on having this kind of range of sizes in your setup. In the plans section of this site are the diminsions and descriptions of how to make these tips.
This is a handheld annealing torch. It is about 6 inches long and 1 inch in diameter. There is a screen across the top of the opening to keep the flame outside of the torch body. The torch produces a flowing transparent blue flame that wraps around the item being annealed. While it is not necessary to anneal most pieces of pyrex, there are some exceptions. This torch is used to pre-heat completed tubes that have to be worked on. By preheating the tube, the chance of a stress crack is significantly reduced.
The torch is homeade from pieces of brass tubing and bar stock. This torch is much used in tubemaking and you should plan on having one. See the plans section of this site for how to make it.
Note that we did not describe any bench torches. This is because no bench torches are used in tube making. It is much more practical to support the tube parts carefully aligned in place, and move the torch rather than support the torch and try to by hand hold the tube parts in place.