SpudFiles

Hi, i've seen this site a long time ago and started a project a couple years ago but unfortunately it never got finished. 3 years later im back wanting to finish this thing haha. Its basically a coaxial with 1/2 inch copper and 5/16 brakeline. I have made a coax before but not nearly the length i have this one. Basically i have everything like the wooden stock and all the materials but there is one thing holding me from epoxying that thing up. I cant find a good way to keep the barrel in the perfect center of the copper tube without blocking airflow. I have tried a cast epoxy method with the sides cut but it wont work out for me. I am looking for it to be accurate as possible so i want it perfectly in the middle. I of course have searched this site over but that part always seems overlooked with the pictures. Any help would be greatly appreciated. I know many of you have built long coaxials that need one for the same sizes as i have. Help a man out and solve this 3 year old work in progress haha.

i glued 3 sticks to my barrel in a Y paten and ground them down to fit tight

I zip tied 3 short pieces of poly tube to the barrel. They crush slightly and evenly space the barrel. A second trick.. don't place it right at the breech where the expanding air flow is the fastest. That causes high loss. Move it back into the chamber a ways. The flow is slower and the losses are lower.

My Mouse Musket and GB Bazooka coaxials both use this.. I'll try to grab a pic of the GB one later. It was an earlier build and so the tubes are closer to the breech and can be seen.

They are out of sight due to the wide valve seat in the Mouse Musket.
They are about 8 inches from the breech.

I found that an old spool of thread has a nice spoke pattern and the ID fits the outside of airsoft calibre barrels pretty well. I just cut it in half then filed away at the "spoke" things until they fit well in my chamber. This gave my barrel lots of support with and only added minor turbulence.

jor2daje, you are a genius. Thanks for all the help. Shes about to be all sealed up tomorrow. Now i have to finish up that stock. Thanks all for the quick replies.

As promised, here is the support for the Golfball Bazooka. This is a coaxial with a 1.5 inch golf ball barrel inside a 2.5 inch thinwall chamber. The barrel is supported by a couple of sets of poly tubing. The tubing was drilled in the middle crossways and a zip tie was threaded through the holes. The tubes were spread out and zip tied into place. In the photo below you can see the ones nearest the breech. It is sturdy, accurate, and has great flow.

The Mouse musket uses the same thing, but it is spaced further from the breech. The Mouse musket, a short launcher, has just one set of supports about 1/3 the way from the breech. The GB cannon has 3 sets of support along the barrel due to it's length. This gives the GB barrel excellent support.

I wrap my barrel in duct tape so that it is a tight fit and the use an exacto knife to cut out two fourths opposite each other

I used gorilla tape, in 4 in lengths going parallel with the barrel.

The tape was layered, and i used trail and error to fine the right number of layers. For MY 4'' chamber 3'' barrel, it was 27 layers of tape, 4'' long and 1'' wide.

I made 4 such stacks of tape, spaced evenly around the barrel. in 3 locations.

So, to sum up all those crazy numbers.... 4 stacks of 27 layers of gorilla tape, evenly spaced around the barrel, in 3 locations.

Hhahaha lots of numbers.... its really easier than it sounds... i was able to apply the tape in about 5 minuets.