I am totally new to this craft. I’ve never molded or cast anything before but I’m trying to create more durable replicas of 3D printed toy accessories. My goal is to create two part molds for items like shields, swords and hands. I would like to 3D print the template for my mold so I can have a permanent template that I can go back to once my mold is used up. Since I’m new to all of this I’m not entirely sure where I should place my vents to optimize my casting while making clean up easier and not compromising features like blade points. This is what I’ve come up with so far.
Is the vent in a functional place? Should it have a minimum diameter? Right now the vent is off the widest part of the blade and has a 1mm diameter. Should the pour hole have a minimum diameter? Right now it is off the hilt and has a diameter of 1.5 mm. Should there be a minimum thickness for the walls of the mold? I have it currently set to be 5.0 mm thick.
Any info regarding what materials would be best to create a flexible mold holding great detail and what materials should be used for casting semi rigid durable casts would be greatly appreciated.
Question: how big is the toy itself? That is a bigger factor on the end product than the size of the vents. Without knowing the size of the finished product, I'd say add one more (at least) vent on the same side as the one near the tip.
And be sure to use a "slow" type resin or whatever you are making them from. A slow type means a longer "open" time and if you have a two piece mold then that will be better for getting into all crevices before the pour hardens.
As for a mold material, I'd use one of the HS (High Strength) series and they're the easiest to use and make great long lasting molds that are strong but flexible. It's my go-to for non-food molds and I'm known to abuse my molds so they can handle a lot of handling.
Thanks for the tip on resin and mold type notoes. The end product will be 3.238" (8.23 cm) long and 0.103" (2.6 mm) wide at the blade and 0.383" (9.7 mm) wide at the hilt. I'll put a second vent on the hilt to avoid an air pocket there as well.
Is there a minimum thickness recommended for High Strength molds? Right now I have it modeled so there will be at least a 5mm thickness from the sword to the outer surface of the mold. I don't imagine I'll need to deform the mold by much to free the product since it'll be in two parts but I would like to eliminate the risk of potentially tearing the mold. Could I get away with a mold thinner than 5 mm and save on materials?
As for the "slow" resin - definitely something I will need to use. Can you recommend a specific type or blend that would best replicate the look and feel of plastic toy accessories? I'm not looking for something totally flimsy but I want to stay away from the brittle side of things as well as pressure will need to be applied and some torsion forces can be experienced moving accessories in and out of action figure hands.
You're welcome. In general, it is recommended you have at least 1/4" around the item to be molded so your 5 mm would be the right size, I usually wouldn't go below that as it would then lessen your tear strength that the mold material is rated for. Now you could do to save on materials is go with a "shaped" mold and have 1/4" around all edges. But for something that small, it probably wouldn't do much good so I'd go with the box as it is in your pictures.
You won't need to worry too much about tearing with the HS series, they're built for a "flexible" strength - normally when I have a hard to remove item, I have to cut it with scissors before it will ever rip. And if it's the right thickness, then it will stretch way before it will rip.
I normally use RC-3 since I need the hardness it provides for castings that are used over and over - I make custom candy molds and I have a few designs that have been bought several times so I'm making new candy molds from the castings a lot and the mold box will break long before the castings will. Once fully cured (and the item is thick enough), the RC-3 castings are very hard to break. RC-3 is the product used for rock climbing hand holds if I'm not mistaken so they need to be strong. Now as for the look and feel of plastic, Alumilite does have some plastic types in their line but I personally haven't tried them yet so I can't speak to how they look and feel and hold up to pressure. Just be sure to not get the one that you can reheat and reshape.