Questions about glue and brass tubing

Small Parts has all kinds of stuff like that, but their shipping is pretty stiff.
http://www.smallparts.com/

Scott is right about the gun barrels. You'll never find brass tubing small enough to represent 20mm in 1/48, let alone .50 cal. My local hobby distributor, who I consider to be a loathesome individual, supplies me with barrels for .50 cal. and 20 and 30 mm. But he charges me an outrageous price. He buys them in one-foot lengths at about 50 cents and cuts them to 1-inch lengths which he sells for 50 cents each. There was a company that advertised in FineScale, in fact, two companies, one based in Houston I remember, that supplied stainless steel tubing in all sizes and several lengths for reasonable prices. Can someone remember the names? It wasn't so long ago. Maybe that's one for the editor. And don't forget those insulin syringe needles for pitot tubes. Just stick in a length of fine wire, cut to the right length, and it not only looks perfect, it doesn't break off.
TOM

QUOTE: Question #1. How do you use Ambroid ProWeld ? It has a brush in it but being a welder type solvent won't that put too much on and ruin the plastic? I have a steady supply of insulin syringes, if I use it in these will it interact adversely with the plastic and rubber in the syringe?

Never used Ambroid but I use Tenax a lot. I wouldn't use the entire syringe, just the needle. I use a hypodermic needle that I cut the point off of, beveled it slightly, then polished with a Dremel tool. I stuck a piece of plastci tube on the back for a handle, and it works fine.

QUOTE: Question #2. What would be the proper size for brass tubing to replace machine gun barrels in 1/48? or for 20mm cannon barrels? I know that to cut the tubing you roll it under a sharp #11 xacto blade until it cuts. Would I be better off buying a small tubing cutter?

To calculate any scale distance, just divide by the scale. A .50 caliber machine gun bore is 1/2" in diameter, divided by 48 is 0.0104". The outside of the barrel would be about 1" (maybe 1 1/4") so it would be 0.0208" to 0.026" in diameter.

A 20mm cannon bore would be: 20 / 25.4 (to get to inches) / 48 = 0.0164". The outer diameter is probably 1 1/4" to 1 1/2" so that would be 0.026" to 0.031".

If you use stainless steel for the barrels (I don't think you'll find brass that small), cutting them witn an Xacto might be difficult. In fact, cutting them with a tubing cutter might be tough because stainless is so much harder than brass. You may have to cut it with a Dremel and then clean up the ends of the cut some.