SpudFiles

Hey guys. I was wondering how do I get a barrel measuring 4.1mm or 5.1mm inner dia. For steel bbs. I can find any tube which would suffice my needs. From where can I get it or who can make it or how can I make it myself ?
It's really important for it to be of precise size as I'm building a full auto bb gun involving solenoid valve and arduino . Since only a little amount of air will be passed at once, It should be efficiently used.
Thnx

Hi Steve,
I purchase K s brass tubing from my local hobby shop (Australia)
http://www.ksmetals.com/26.html
I use both 5mm and 6mm tubes to use 4mm and 5mm ball bearings. With a wall thickness of 0.45mm the internal diameter is 4.11mm and 5.1mm. I use 12" lengths and sleeve them in the next sizes up for added stiffness. They do make longer lengths.

noticed last week that their 1/4" (6.35mm) stainless steel tube is 22gauge wall thickness which if my calculations are correct should be 5.07mm internal which would help accuracy. Plus being stainless steel there should be less wear. $9aus from my lhs, so will be buying this for my next qev build when some parts arrive

Hope this helps

Mike

I would use McMaster Carr here

https://www.mcmaster.com/#seamless-tubing/=16vcmch

but depends on your location I guess

K and s brass tubing 3/16 external diameter (4.762mm) wall thickness 0.356mm = ID 4.05mm. Comes in 12" and 36"

Mike

You may use the 4*6 PTFE tube,or gel ink refill and make them up by tape.
I've used the gel ink refill as barrel in my program
http://www.spudfiles.com/miniature-cann ... ml#p383803

I make my own pipes with a metal tube and epoxy resin. You just have to get a rod of the caliber you need, straight, center on the big tube, on both ends, cover one of the sides and fill with epoxy. You must not forget to oil the rod that determines the size because if it sticks ... it does not work at all. The rod that determines the caliber you are looking for must be removed without much effort.The rods can be of any material but must be completely straight.

It's done like that. I have used them a lot even in a hybrid, with ammunition made of plastic, steel and lead, and the resin holds. It is important to lubricate with graphite, from a pencil, to achieve lubrication that lasts and without smoke. I hope you solve this method.

now you got me thinking

Any specific type of resin, I guess it must be pretty free flowing

farcticox1 wrote:now you got me thinking

Any specific type of resin, I guess it must be pretty free flowing

I'm not sure I understand well by the language.
I imagine you want to know what resin I use for this.
I have built this with this epoxy resin, the one in the photo. I have also built them with polyester resin, and I have had no problems. Logically they are of smooth soul.

Logically they are of smooth soul.

I guess you mean "not rifled" or smooth bore

It would be a good way to make a rifled barrel with the right mandrel, although the epoxy would probably wear out very quickly in a high performance launcher.

Jack, I'm surprised you didn't mention your adventures in casting barrels, what, 7 years ago with your 9mm pressure washer launcher. The problem I presume with epoxy barrels (well any sort of plastic) in hybrids is of course the erosion. As a breech plug there is less of an issue as the gasses are relatively stationary. But the throat of a barrel would burn up fairly quickly unless you had an insert.

jackssmirkingrevenge wrote:

Logically they are of smooth soul.

I guess you mean "not rifled" or smooth bore

It would be a good way to make a rifled barrel with the right mandrel, although the epoxy would probably wear out very quickly in a high performance launcher.

Yes, I mean that, without stretch marks. In fact, although I bought a .22 barrel with flutes, made of steel, 45 cm long, I use the smooth barrels for the tests, the prototypes. They hold up well as far as I tried. I imagine that with high powers they will not last long, but I cannot really estimate how far they will endure the opening.

hectmarr wrote:Yes, I mean that, without stretch marks.

Search for "stretch marks" in google images

Jack, I'm surprised you didn't mention your adventures in casting barrels, what, 7 years ago with your 9mm pressure washer launcher.

Well remembered! It did not go well...



thread

I see that it did not work in your tests. Possibly you omitted the lubrication, I do not know.
My procedure is to paint with a soft pencil the rod that gives the size of the caliber of the barrel. When the rod comes out, that was when introducing it of bright black color, by the graphite, it leaves without anything of this. Everything has stuck to the resin on the inside surface where the ammunition passes. The adjustment is intermediate, neither very olgado nor very fair. Ammunition does not fall by itself due to gravity. The rod that I use are plastic and hollow, Inside I install a carbon rod to leave it completely. The outer tube, which contains the resin, is 5/8 "structural pipe, sanded inside and degreased so that the resin sticks perfectly.
This photo is from the small hybrid prototype 1 cannon that has already shot more than a thousand times, about 4 boxes of .22 spherical lead ammunition and it is perfect. This cannon is united because it was short.
In prototype 2, the one with the loading system, of the last video that I published, has already shot 6X 682 times, and it is perfectly fine. I have not uploaded photos of this canyon because it is armed and I am using it at this time.
Well, I wanted to explain to you how I did it.