Amounts By Volume Of Molding Supplies And Plastics

Spartan137

Well-Known Member
This is a pretty easy question to all members on the board who have used silicone rubbers and poured plastics.

All I'm looking for are rough numbers regarding how much will be required for certain pieces of armor. The following two questions are essentially what I'm looking for.



1. How much silicone rubber will the part need for a full mold?

2. How much poured plastic will the part need to make a single cast?



Those two questions are the basis for my question. I'm gonna list a series of parts that I want to cast, and I'd like any molding experience member to help me out.



1. MJOLNIR Mk VI Helmet

2. ODST Helmet (Rookie variant)

3. Ma5B/Ma5C Assault Rifle

4. BR-55 Battle Rifle

6. Full Mk VI Suit

7. Each individual piece of the Mk VI suit



And that's all I have for the time being. I'll be very greatful to any member who can assist me.



EDIT:



Also, I'd like to know things like "How many parts of x can I make out of y amount of plastic". Same question applies to the above 7 questions.
 

ACDCrockr209

Well-Known Member
I'm gonna list a series of parts that I want to recast


Ummm, no. YOU CANNOT RECAST!!!!! It is frowned upon here and anywhere else that casts props.



You can only cast YOUR OWN ITEMS THAT YOU CREATED!!!!



If you cast your own items then thats your business. If you cast other people's projects, then you are going to be put on the wall of shame.



Oh, and good luck trying to buy any more props from anyone.



-Pony
 

Farquaad

Jr Member
I just assumed he was talking about things he has made. Why the assumption that he's referring to stuff others have made?
 

Richie

Jr Member
Lord Farquaad said:
I just assumed he was talking about things he has made. Why the assumption that he's referring to stuff others have made?
Because, he likes to jump to a conclusion as fast as possible.
 
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Spartan137 said:
I'm gonna list a series of parts that I want to recast, and I'd like any molding experience member to help me out.


thats the only reason, really. but ive also asked if its a mistype. so no one is passing judgement yet, just making sure. however after quickly browsing thru topics and posts, i didnt see any WIP threads, or progress pictures. mainly general discussion topics and questions and a few WTB posts. i apologize in advance if recasting is not an issue, but ive got to look out for all my fellow members' work.
 
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Farquaad

Jr Member
Fair enough, I guess I'm still a bit naive about this kind of thing since I haven't really put anything I've spent time working on 'out there'. But I have seen several threads where people have gotten burned by having their stuff recast and sold so I guess I can understand questioning his motives.
 

Spartan137

Well-Known Member
/Facepalm



I know recasting is frowned upon. I know guys who have been banned for it.



Scratch the word "recast" and just replace it with cast. I'm working with original models, here. Reason you havn't seen any WIPs that will be casted is because there aren't any. I'm thinking about having parts CNC'd by a friend of mine, but not until I work out all the numbers first. And the guy who'd do the CNC'ing is ON the wall of shame. So I know the stakes of the business.



I'm not recasting other peoples work. Let's clear that up here and now.
 

mroreo123

Member
Well, now that the re-casting issue has been resolved...



Spartan137 said:
1. How much silicone rubber will the part need for a full mold?

2. How much poured plastic will the part need to make a single cast?


I haven't started molding yet, but I looked at Smooth-On's website, and they tell you to first find the total surface area of your model. I've been thinking about how best to figure that out for complex-shaped models like our armor pieces.



The easiest solution I could come up with was to take plastic wrap, and wrap several pieces of it (using the full width of the roll and only cutting along the length) with as little overlap as possible. A little overlap should be okay, since it will give you some margin of error (better to have a little too much than too little, right?). Once the piece is fully wrapped, take off the plastic wrap and lay the pieces end to end and measure the overall length in inches. Length times width of the roll approximately equals your total surface area.



Next, take that number times the recommended thickness, which I believe is 1/4" to 3/8", for the total volume needed. Smooth-On lists their products with a cubic inches/pound measurement, so take your volume and divide by that figure (25.8 cubic in/lb for Dragon Skin, 23.6 for Rebound 25) for the weight you need.



Finally, take that weight and divide by the weight for a gallon of Dragon Skin/Rebound 25 (16 lbs/18 lbs, respectively).



So...



total surface area X thickness / density / weight per gallon = gallons of product needed



And there you have the answer to question 1. :D

Question 2 should work the same way, just change how thick you want to cast your pieces.
 
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Beau Nidle

Jr Member
Well, I can save you some math when it comes to the mk vi helmet, since I've molded one. ;)



I used about half of a gallon kit, which is roughly the equivalent of 4 smooth-on trial kits, but to be honest I could have had a perfectly servicable mold with 3 trial kits. As for casting, again going with the smooth-on stuff, you will probably use close to 2 trial kits of plastic, more if you're a little inexperienced with casting. As you get better, you'll use less.



I then used the other half of the gallon kit to mold 2 mk vi shoulder pieces (left + right). So that's one gallon ($175) making a helmet and 2 shoulder piece molds. It probably could have gone a little further, but not much. Unless you only plan on making one of each thing, in which case you can make your molds super thin and it doesn't matter if they tear after the first cast is pulled.



PS: "Casted" - not a word. It's cast. Always cast. ;)
 

Spartan137

Well-Known Member
Beau Nidle said:
PS: "Casted" - not a word. It's cast. Always cast. ;)


Hehe, see? I know nothing about casting stuff! Between that and the 'recasting' fiasco, it's pretty obvious I have no idea what the hell I'm doing!



Anyway, thanks MrOreo and Beau, the assistance is greatly appreciated! Hopefully with this information, I can get about what I need and some extra for errors.



There is one last piece of information I'll need, and that's for how much Silicone and plastic it'd take for an Ma5B/C Assault Rifle. If anybody knows, please tell!
 
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we are right there with Beau, we used about half a gallon (give or take) for Dutch, and our Rookie should take about the same. if i remember right, i think i was told that you could get 3-4 assault rifles out of a gallon of plastic. i dont know about the rubber amounts tho.
 

Beau Nidle

Jr Member
You're welcome. :)



If I was estimating, I would suggest investing in a gallon of silicone for an AR. There might be a little left over, or you might need to buy an extra kit to finish it off. Don't worry if you don't buy quite enough, silicone will stick to itself pretty well, especially when it's fresh.
 
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