How to cast small gun barrels?

[Dr. Snuts, M.D.]

I plan on casting some thin gun barrels in about 1.32 i think. Now i was wondering if getting resin in the mold is even possible... Would I use a syringe to force the resin down the narrow tube? I'm trying to do it relatively cheap and i can't really think of anything. My only other option I think would be to cast everything but the barrle and use some kind of metal tube for the barrel to ensure strength. Any ideas?

[Joseph Osborn]

Barring the use of vacuum to help evacuate the air from the mold, you really need vents to make sure the resin gets all the way to the bottom of the barrel. You probably want to make a one-piece mold to eliminate an ugly parting line on your barrels, right? If so, venting will be problematic. If you make a 2-piece mold, then just add a vent at the barrel ends and route it to the upper side of the mold to let the air out as the resin is poured into the mold. Hope this helps, and if needed, I can draw picture or something to help clarify. Look on Google for "resin mold vent" and you'll probably get some good references.

[Chacal]

How big are the "originals" you're trying to model in 1:32, or better yet, how big will the modelled barrels be? If you're talking something smallish, like a 20mm cannon or so, I'd suggest using a small tube (from a hypodermic needle for example) as the barrel and doing the rest with resin. If it is bigger (around 1/8" in diameter) I'd cast it solid, drill an opening then ream it wider with a conic tapered dremel cutter. Only if it were bigger than 1/4 of an inch (which is a pretty big gun, if I may say so) I'd try to cast it with an integral muzzle (and even so, I'd go with a smaller caliber of muzzle then I'd ream the opening to the desired thickness)

[Schadenfreudian]

As Chacal says, without knowing exactly what you're trying to cast, it's hard to give advice. However, this is what I did to cast secondary and tertiary guns on a 1/1200 scale battleship kit I made. I used 0.5mm thick styrene as the gun barrels on the masters and made a two-piece mould for the turreted secondaries (the four small triple turrets clustered near the stern), while on the hull the tertiary gun barrels (in the little domed twin mounts around the funnel) were integral with the hull. When casting, I prepared the moulds by inserting roughly cut lengths of 0.5mm styrene rod in all the 'holes' left in the mould by the masters' gun barrels; when the resin was poured, I made sure it ran around the styrene rods thus embedding them. When the cured parts (one hull and four secondary turrets) were removed from their moulds, the result was styrene rod gun barrels embedded in them.

If you look at this image (click on 'full size'), hopefully you'll see what I mean (the styrene rods are white, the resin is cream):

http://img.photobucket.com/albums/v102/ ... ting-4.jpg

The large barrels on the three main triple turrets forward are resin, and actually form part of the air venting channels in the two-piece moulds I made for those parts.

[Kenny]

I plan on casting some thin gun barrels in about 1.32 i think. Now i was wondering if getting resin in the mold is even possible... Would I use a syringe to force the resin down the narrow tube? I'm trying to do it relatively cheap and i can't really think of anything. My only other option I think would be to cast everything but the barrle and use some kind of metal tube for the barrel to ensure strength. Any ideas?

I haven't done any barrels, but...

what about casting them as you have said using a syringe and needle to feed the resin in from the bottom/tip of the extra long barrel and then cut off the end where the bubble will probably form?

[Dr. Snuts, M.D.]

Thanks for all the advice guys, it certainly has given me a few more ideas. I plan to give it a whirl sometime this week. For the record, I don't recall excatly what the kit was but its a WWII German anti aircraft artillary gun called a Flakverling...something or other.

[futch]

try a 2 piece mold that fills your barrels from the bottom up. ie, think of the letter U. you pour down one side, it fills up the other side forcing air out the top. here 'v' denotes resin going in and '^' denotes air escaping

v ^
||_|

if you have a number of pieces to cast, then 'gang' them up in parallel. pour down the same hole as described above;

v ^ ^ ^
||_|_|_|...

[Umi_Ryuzuki]

I do almost exactly what Futch is describing.

The right side has an additional sprue over it, and there is a third anchor
over the stack in the mold. then air outlet sprues. over all.



http://img443.imageshack.us/my.php?imag ... 059hv2.jpg