my current project is a tank that has a gun barrel (much like a contemporary tank). I intend on selling it as a kit, so i'll be reproducing the gun barrels. I haven't cast thinner resin pieces but i fear warpage in the long run.
my question i'm posing is whether to provide a brass/aluminum barrel (for the kit) and resin muzzle....or should i cast the whole barrel and muzzle in one piece? i want to provide a product that a modeler doesn't have to fix to correct.
is there a minimum advisable thickness i shouldn't go beyond...especially for a longer element (like a 3-4" long barrel)? I'll prob go with the smooth-on products...i'm assuming some resins may "sag" more than others?
Many thanks
casting barrels
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Umi_Ryuzuki
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Drill the back of your master, and place a 1/16" or 3/32" wire into the hole, and allow it to stick out about a half inch.
When you make your mold, and pull out the master, there will be a nice 1/2" groove at the back to place a 2-1/2" - 3" long wire. It will sit nicely in the groove, and the extra length will be buried in the resin of the larger barrel.
When you make your mold, and pull out the master, there will be a nice 1/2" groove at the back to place a 2-1/2" - 3" long wire. It will sit nicely in the groove, and the extra length will be buried in the resin of the larger barrel.
m'nutz,
good point. i like the idea. but this isn't your daddy's barrel. the mount is a little detailed and was consider pressure casting it to get all the detail. will the quick setting resin be TOO quick for the idea pressure (which is what?) to be reached in a 2.5 gal pot using an iwata sprintjet compressor.
umi,
like your idea too...however. that idea (if i underundstand it correctly) would only work for a barrel that doesn't have a finished end. I would not be able to produce the barrel your way with the muzzle end cast. would the reinforcing wired be trimmed inside the muzzle? perhaps i could cast the reinforced muzzle and use the extra reinforcing wire hanging out as a means of pinning the (separately cast) muzzle onto it.
thankx for the feedback ....hoping to get more.
good point. i like the idea. but this isn't your daddy's barrel. the mount is a little detailed and was consider pressure casting it to get all the detail. will the quick setting resin be TOO quick for the idea pressure (which is what?) to be reached in a 2.5 gal pot using an iwata sprintjet compressor.
umi,
like your idea too...however. that idea (if i underundstand it correctly) would only work for a barrel that doesn't have a finished end. I would not be able to produce the barrel your way with the muzzle end cast. would the reinforcing wired be trimmed inside the muzzle? perhaps i could cast the reinforced muzzle and use the extra reinforcing wire hanging out as a means of pinning the (separately cast) muzzle onto it.
thankx for the feedback ....hoping to get more.
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Umi_Ryuzuki
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umi..
i'm a little confused.
i thought you drill and insert the rod into the master...to leave an extra space in your mold to HOLD the reinforcement wire OUTSIDE the actual cast piece....then snip it off. the extra space is like a place to hold the wire to let it "levitate" in the center of the cast rod..as the resin hardens.
how does the wire "levitate" at the muzzle end if there is no place for it to rest before the resin sets up?
thanx again.
i'm a little confused.
i thought you drill and insert the rod into the master...to leave an extra space in your mold to HOLD the reinforcement wire OUTSIDE the actual cast piece....then snip it off. the extra space is like a place to hold the wire to let it "levitate" in the center of the cast rod..as the resin hardens.
how does the wire "levitate" at the muzzle end if there is no place for it to rest before the resin sets up?
thanx again.
QC, you may have a point there about the cure time.
How quickly will your compressor bring the pot up to 40 Lbs of pressure?
I pressure cast stuff all day long using SC-300 and I rarely run into issues.
I'm certain that the details will be reproduced fine.
If you find that your pot takes too long to reach full pressure, you could reduce the internal volume of your pressure pot for a faster charge.
A few bricks or other solid, bulky objects in the pot would suffice.
Umi's idea of incorperating a rod into the casting is also a great idea..guarentees a straight, solid barrel.
How quickly will your compressor bring the pot up to 40 Lbs of pressure?
I pressure cast stuff all day long using SC-300 and I rarely run into issues.
I'm certain that the details will be reproduced fine.
If you find that your pot takes too long to reach full pressure, you could reduce the internal volume of your pressure pot for a faster charge.
A few bricks or other solid, bulky objects in the pot would suffice.
Umi's idea of incorperating a rod into the casting is also a great idea..guarentees a straight, solid barrel.
i was rethinking what umi said..
and at first was thinking of the barrel in terms of the barrel being cast on the horizon (in landscape....aka pointing left and right)
the only way i can see the rod supporting itself is if the barrel was pointing straight up (muzzle at the top).
but for this to happen...you would have to pour "into" the muzzle and have the vent come from the base of the barrel.....thus the tip of the muzzle would have to be hollowed out (to represent a hollow cylinder) by the modeler.....and not to fond of...
i was hoping to have the muzzle cast where it has a small recess..or dimple....giving the slight effect of being a long hollow cylinder.
maybe i should do what will make the best product and trying to make it soo easy on the person constructing the model.
and at first was thinking of the barrel in terms of the barrel being cast on the horizon (in landscape....aka pointing left and right)
the only way i can see the rod supporting itself is if the barrel was pointing straight up (muzzle at the top).
but for this to happen...you would have to pour "into" the muzzle and have the vent come from the base of the barrel.....thus the tip of the muzzle would have to be hollowed out (to represent a hollow cylinder) by the modeler.....and not to fond of...
i was hoping to have the muzzle cast where it has a small recess..or dimple....giving the slight effect of being a long hollow cylinder.
maybe i should do what will make the best product and trying to make it soo easy on the person constructing the model.
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Umi_Ryuzuki
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Unless you are using a 1/8" or 5/32" rod, it shouldn't be so heavy that it would "sag" over that length. The muzzle could be hollow up to a 1/4" or 3/8" deep, behind that would be the rod, and the solid resin.
The resin would form the muzzle, to every last detail, and be integral, and cast with the barrel. The barrel would have the rod inside and sticking out the back. Since it is a solid barrel, the rod does not have to be perfectly centered, just "Not" sticking out the side.
Hopefully that clears up any confusion,...
Don't make me build one...
The resin would form the muzzle, to every last detail, and be integral, and cast with the barrel. The barrel would have the rod inside and sticking out the back. Since it is a solid barrel, the rod does not have to be perfectly centered, just "Not" sticking out the side.
Hopefully that clears up any confusion,...
Don't make me build one...
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Chacal
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Maybe if you cast the barrel in white metal, you'd get good results. The setup for the mold is very similar (you have to get high-temperature rubber, but everything else is the same—or almost), and as the white metal is not "sticky" and it is very heavy, it will conform beautifully to the mold.
If the barrel is not too big, it won't add much to the overall weight of the model/kit.
If the barrel is not too big, it won't add much to the overall weight of the model/kit.
Last edited by Chacal on Wed Nov 07, 2007 11:35 am, edited 1 time in total.
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Slide
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i see what Umi's getting at, but wouldn't a wooden dowel work better, ans the wood would absorb some of the resin making an even stronger bond?
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