how should I mold this?

[mastersword64]

Hey guys. I am going to be molding this P99 and need some help on how I should divide the mold. The polymer grip has the magazine housing which is throwing me off a little. Id like to cast it as a one piece grip. If you look at the pic, you can see the seam down the center of the pistol which they used for the molds I guess. Its more prominent on the trigger guard area. That mag housing is really throwing me off. Thanks.

-Shane

 

[mastersword64]

another picture

 

[Terrell78]

Why not just buy an ASP red gun of a P99.

http://www.chiefsupply.com/Law_Enforcement...ng_Weapons/7327

 

[mastersword64]

because I need all the parts separate and identical to the original piece

 

[Terrell78]

<div class='quotetop'>(mastersword64 @ Nov 17 2006, 03:03 AM) [snapback]1359624[/snapback]</div>

because I need all the parts separate and identical to the original piece
[/b]

Oh ok. Would a P99 airsoft pistol with removable slide and magazine work?
http://www.redwolfairsoft.com/redwolf/airs...menu2=561#20462 Second pistol down.

 

[GrenadeKing]

I think he already has the gun and is trying to figure out how to make a mold of it so as to get the best possible cast.

 

[mastersword64]

Yes grenade king. I have the P99, just want to make a resin copy of it with a silicone mold.

 

[Blad]

mastersword64, not being rude, but I've seen cheap airsoft springer P99's from $5, cheaper than a resin cast would be and much, much cheaper than the silicone you'll use.

However if you still want to make silicone moulds of the grip frame, slide and mag, you'll either need to make three separate 2-part moulds, or if you wanted to copy the grip and frame exactly you'd need to make 2 separate 2-part moulds (one for each half of the frame), the magazine could be another 2 part mould and the slide another 2-part.

Look at Dan Perez's fantastic guide for a better idea.

http://www.danperezstudios.com/workshoppag...ing_casting.htm

Cheers.

 

[mastersword64]

I know, airsoft guns are cheap. A lot of them are also garbage. This is a learning experience for me actually because I am having a friend design some guns using a CAD file and a CNC machine and we are going to be molding them for different kits. I need to do this. Not buy an airsoft which wouldn't do me any good. I was thinking for the mold for the frame, have two side parts to the mold that only go up to the top of the frame edge. Then create another part on top of those two pieces which detail the inside of the frame including the mag housing. I have a drawing I did which I have to get around to scanning. So basically, it would be a 3 part mold. The two halves and the top which does the inside curves of the frame and the mag housing.

 

[Blad]

I see what you mean, but I don't think it's practical. With a 3-part mould like that you'll have lots of potential bubble traps, difficulty in correctly registering the mould so you avoid areas that may be too thin due to compression or slight mis-registration, plus the complexity of making a 3-part mould in the first place.

You'd be better off splitting the frame following the original mould lines and make 2x2-part moulds. That way you should have better control over bubbles etc.


Second thoughts:

It is possible to make a 3-part mould in the way you've described. If you make a 2-part mould for the frame leaving the entire top of the mould open along the top of the frame making sure you build in several areas for registration at the top.

Then mould a solid plug for the inside of the frame & mag and sit it ontop of the 2 lower 1/2's. The only probelm would occur when casting as you'll need to fill the mould about 1/3 full (a wild guess.) swirl for a few seconds then drop the top 'plug' in alowing some of the resin to either overspill the top, or make a couple of vents in the top plug along where it would line up with the top of the frame.

Obviously some trimming and overspill would happpen, but as long as the moulds and plug you use are solid (at least 2cm thick), it should work.

I do a similar thing with some belt buckles.

 

[Jedirick]

I did molds of portions of my UZI several years back.

All I have to offer is make certain you seal every nook and crevice that may lead to internal working parts. Silicone is incredibly invassive and you will find yourself endlessly digging little pieces out of everywhere in order to get the gun back in functioning order.

 

[mastersword64]

ok wonderful. great responses. thanks. any other suggestions?

 

[Matsuo]

Creating a magwell on a 2 piece mold is always tough.

This is one way I saw around that on the AR receiver. You can see the locating tabs I made for the mag well plug so that it stays on center, if you don't and the plug is misaligned one wall of the pistol grip will be thicker than the other and the clip will go in crooked.

These kinds of molds are really tough as Blad mentioned, as there are tons of places for bubbles to get trapped.

Hold the piece up and examine it, remembering that bubbles float upward try to imagine how and where bubbles might be trapped and arrange your mold in a way that minimizes this...pre planning goes a long way.

If you don't have a means to de-gas the silicone, a good way around this is to use slightly less activator and silicone thinner to help minimize bubbles.
The thinner makes it easier for bubbles to rise out and escape and using less activator prolongs cure time giving the bubbles more time to rise out.

Matt

 

[Vaderman]

Hey, RPF member Adam Savage has a nice little tutorial on making rubber molds in the current issue of "Make" magazine, the one with the pinball machine on the cover. It has some great tips.