My Br55 So Far

[rube]

I had hoped to have the molds finished this weekend but work (real job) got in the way. Here's what I did get done.

The forward sight rails would lock into the mold without filling the gap between them so I made a removable block of Bondo to fill the space.

I then covered the block in a 1/4" layer of clay and a plaster mother mold shell so I could get a rubber copy.
The rubber block will be inserted into the mold when casting and held in place by a dowel.

Mother mold for the upper receiver. Constructed to use the minimum amount of silicone.

 

[Anubis117]

very nice. i'm assuming the piece of "bondo" on the finished pull of the mold will not be removable.

keep it up Rube! you're work never ceases to impress.

 

[rube]

The Bondo part existed only as a master for the rubber version. The rubber part will be part of the mold and remain with it making this a three part mold.

 

[box o crayons]

so is the rubber piece going to be removed in the end either way it looks amazing and are you going to use rebound 25 on the whole thing with no mother mold

 

[rube]

I'm using Smooth-Sil 950. I wanted a much stiffer rubber for a mold this size. The plywood box is the mother mold.

 

[Anubis117]

The Bondo part existed only as a master for the rubber version. The rubber part will be part of the mold and remain with it making this a three part mold.

ah ok cool. i wasn't fully understanding what you were doing.


man i can't wait till i have money and time to actually start this type of thing. keep up the good work rube.

 

[Easyrider1972]

With this awesome accurate progress we could see a whole battalion of USNC marines just waiting to troop!

This kind of enthusiasm and hard work is what will make the 405th trully huge and impressive.

All Conventions, expo's and Con's.....look out! the 405th is coming!!!!

Nice work friend. I am left swallowing with anticipation.

 

[Spartan648]

I had hoped to have the molds finished this weekend but work (real job) got in the way. Here's what I did get done.

The forward sight rails would lock into the mold without filling the gap between them so I made a removable block of Bondo to fill the space.

I then covered the block in a 1/4" layer of clay and a plaster mother mold shell so I could get a rubber copy.
The rubber block will be inserted into the mold when casting and held in place by a dowel.

Mother mold for the upper receiver. Constructed to use the minimum amount of silicone.

I am sorry that I do not get to this site very much as I miss out on alot
but Super Job on everything I have seen so far, I have been molding and casting
for 25 plus years, wish I lived closer to give you a extra pair of hands to help out

Keep up the good work,

Andrew

 

[rube]

Getting there...

Degassing setup. Some 6" PVC plumbing and a venturi vacuum pump from Harbor Freight. The Mighty Vac is hooked up just for the gauge. I can pull 27" Hg with this setup. I've read that you need 29" to degass completely but this seems to work just fine.

Molds for the charging handle, muzzle brake and the rubber bit that fits between the scope rails.

Upper receiver half done. The other half has since been poured.

 

[box o crayons]

is your rubber blue thats awsome and is the wood mother mold effective

 

[LeeKegan]

Rube it looks awesome. I'm glad you are building these molds. Can't thank you enough!

 

[abrant3]

Wow, dude. You guys that specialize in wood-working amaze me. I think It takes a much better artist to use wood as a medium than any other material. That's the Halo 2 BR, correct? Is the scope you're using a working one? If it isn't, Center Point makes the perfect scope with a laser sight that fits the BR perfectly! That's what I used, anyway. You can find them in pretty much any sporting store/section for about $50.

 

[rowan]

Oh my god that mold is sexy...
Yeah, i went there.

 

[Loess]

Yeah, three Kittays. This is that freeking great.

Wonderful work Rube. Can't wait till I can get a copy of Lee's awesomeness.

 

[EMOD360]

Thats AMAZING i seen many people do their weapons out of wood but i never did understood how they made it, because it looks very complicated and expensive because you need all those tools and wood.
BUT ITS AMAZING WOOOOOOOOOW!!!!!

 

[DerKraken]

Degassing setup. Some 6" PVC plumbing and a venturi vacuum pump from Harbor Freight. The Mighty Vac is hooked up just for the gauge. I can pull 27" Hg with this setup. I've read that you need 29" to degass completely but this seems to work just fine.

Any chance you have a few more shots of your degas chamber? Specifically, where you seal the chamber after you pour in the silicone. Excellent idea with the PVC, I'm surprised that clear PETG pipe (is that what it is?) can hold up to 27" Hg without buckling

 

[smick6]

I have been trying to decide if I wanted to buy one of those vacuum pumps for awile now. They are really cheap there. I assume you are using it to degass the silicone before you pour the mold? I didnt get any bubbles in my silicone but I have been getting more bubbles in my plastic than before. I need to make a setup to decrease the bubbles in the urethane. With the size of some of your molds I wouldnt think you could pressure cast them, so how do you limit the amount of airbubbles in your plastics?

 

[rube]

box o crayons:

The blue stuff is Smooth-Sil 950.

DerKraken:

Not much else to see. It's just a short length of 6" Sch 40 PVC and an end cap. The seal at the top is black RTV sealant. The lid is a 1/8" piece of aluminum that rests on top. I don't pour silicone into the chamber, that would be messy. I put the container I mixed the silicone in into the chamber filled only 1/4 of the way to allow for expansion. I think the tubing is polyethylene. It's not really surprising that they don't collapse given that the maximum pressure differential can only be 15psi unless you're doing a Michael Jackson with a hyperbaric chamber.

smick6:

I think the big ones are going to be hand roto molded (ugh) so bubbles are not really a big issue. I haven't had much trouble with air in the molds on the others except for getting all of the air out of the mold when pouring, not from air trapped in the resin when mixing. I'm using Smoothcast 300 for the tests but a slower setting resin will need to be used to allow more time to let trapped air rise. Pouring in a bit of resin and sloshing it around before pouring the majority coats the mold and breaks the surface tension so bubbles are less likely to stick. I was thinking about building a vibrating table out of an old sander if it became a problem.

 

[hadesphantom]

one word "GODLY"

 

[Seno Ypsamee]

Looks good. Nice job. Can't wait to see how it looks casted.