TUTORIAL: Making Moulds and Casts

[cardyfreak]

At some point I'd like to but some proper gear. A vac chamber and a pressure pot would be awesome. Just so damned expensive!
I know there are ways to homebrew the kit but I'd prefer not to mess up and turn the pot into a hand grenade cos I've bought something that isn't up to spec.

 

[TakUnderhand]

My thoughts too.. And if I were to spend that kind of cash, a 3D printer would be under consideration instead..

 

[TakUnderhand]

Say @Horatio_Tyllis, what model of 3D printer did you print the tech bases on?

 

[Horatio_Tyllis]

Invision SI-2 rapid prototyper.


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[nooker]

I don't know if this helps with your vac chamber desires, but:
http://punishedprops.com/2015/11/23/vacuum-forming-machine/

 

[Horatio_Tyllis]

Not exactly but cool as hell!!!!!!


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[TakUnderhand]

Like that @nooker! I think that would be great for mass producing things like barrels, low walls and stuff. I can see myself giving this a go.

On the topic of a vacuum chamber for casting, a work colleague of mine has constructed a vacuum chamber using a pressure cooker. (he's using his for Science mind you, not moulding!!). Well, if I manage to follow his instructions, I'll write it up on my plog

 

[Slave to Darkness]

They ended up bulging and looking like large butt-plugs because I didn't reinforce the walls,

I am sure you could sell them on ebay or through Fetlife

 

[=][=SW1=][=]

I've had plenty of experience sculpting and casting my own bases.

This threads making me think a little bigger.

 

[TakUnderhand]

I did make a vacuum chamber out of a pressure cooker. It worked, to a point, but didn't hold a vacuum for very long.

In the end, I bought this one. Note, I already had a pump.
It works well. I boiled the air out of some cold water, that was fun.

"anytime now" I'm going to be casting again...

 

[Tiny]

Vacuum chambers are cheap as chips. Mine is just a big saucepan from Costco with a rubber seal around the rim and a 12mm perspex sheet on top for a lid. Vacuum gauge and gubbins pokes out the top. Expensive bit was the pump.

Don't cheap out on a pressure pot though if you're going to get one, they will go bang and hurt your feelings and your face.

 

[Kommissar Shriken]

Hey guy's!

i am often asked how i make my pressmolds and i want to show you in a little tutorial, that its exaclty so easy like it sounds.

of course not each mold is perfect, sometimes you have to try it a second or third time, but it works!

also a good tutorial wis resin is here:
http://sirskofisworkshop.blogspot.com/2013/12/how-to-make-molds-with-oyumaru-resin.html

what do you need?
at first you need the pressmold. i prefer the original and cheap "oyumaru" but you can also use "blue stuff". it's the same material.

its like a clay when you put it into hot water and after colding its hardened.

so lets start:

for example i made a pressmold for some cool orlock-weapons.
the litte but important detail is to press the oyumaru on the edge of the weapons to get each little detail of the weapon moldet (this is also important for making molds from complete minis or parts)

second example are goliath-bodies

next step- adding the 2-component clay.

you can use greenstuff. but i prefer a 2-component resin material like "magic sculp" ... its "softer" and easier to press....

the important detail for a good copy is to "press" the clay into the mold to get each detail. after pressing you shoud smooth the surface (because dont forget we have two sides)

dont forget how the 2 parts of the molds should match.

now you have to press the two sides carefully but strong..

you can also make a frame from lego (i used it for bigger molds)..

and then the result... you can see i added too much resinclay so i have to cut a lot... but after cleaning it will look good!

and after some practise you could get really good and detailed copies from whatever you want!

i hope you like my little tutorial!

HAPPY PRESSING!

 

[undertaker]

Excellent tutorial @Kommissar Shriken! I have been playing around with Oyumaru recently and had some very decent results. Sometimes it helps to put some dents in the unused portions of the bottom side of the mould after you initially press in the original part. That way the top half will mould those dents and you'll have alignment pins! I also found it best to use Milliput for the part, because you can add a bit of water to soften it up and make it go into all the details.

 

[Kommissar Shriken]

@undertaker: many thanks! yes your right with the alignment pins. this works also excelent. i forgot to add this option.

i never worked with milliput, but i will give it a try when my bowl with magic sculp is empty. thanks for your tip!

 

[jamesandhisstuff]

This is a really awsome thred thank you op

 

[Kitcar]

There is a company I used to get two-part casting silicone from in Cleveland OH, I can't remember the name of the company just now. They had formulas for recasting both plastics and metals. That is why I have four Ash Waste Shaman. Almost a psychic choir.

EDIT: It's "Smooth-On".

 

[prewarsalad]

I have been following this guide and it has been going great. Only problem I have is when it comes to removing the plaster from the mold it always cracks.

I am using herculite 2, anyone know where I might be going wrong?

 

[Kommissar Shriken]

I am using herculite 2, anyone know where I might be going wrong?

i think the problem is the herculite... i use a 2 component resing clay. its hard and stabil and never cracked... i'm sure milliput also works.

 

[Stoof]

I have had great results with milliput.

Top tip 1 - To save having to make marks or anything to line up your two mould halves (and to almost eradicate the chance of your halves not lining up): When you are making the bottom half of the mould, use a tool of some sort to make indentations around the edges where nothing is being moulded. When you press the top batch of mould material against the first, it will flow into these indentations and harden in place - when you've put your putty in and press the halves together again, the bumps on the top half will key against the holes of the bottom half - perfectly aligned every time

Top tip 2 - Always use freshly boiled water. The hotter and gloopier your Oyumaru/Blue Stuff, the more detail you will capture in your mould. I go so far as to use a fresh cup of boiled water just between doing the bottom half and top half of the same mould if it's something I want to come out reaaal nice. If it doesn't hurt your fingers when you first fish it out of the water, it's not hot enough.

Top tip 3 - Try and be as precise as possible with the amount of putty you put in. Any small gaps can be filled easily, but a thick flash line can really ruin a part and make a re-mould necessary. With practice you'll learn to gauge it - I now usually get just a very fine flash line which is easy to trim off and little worse than a "real" mould line.

Top tip 4 - If you're using Milliput or a similar putty, keep a couple of pre-made moulds to hand. You will probably have leftover putty and may as well make a base or two or spare weapon for the bits box etc.

Top tip 5 - Remember that Blue Stuff/Oyumaru is flexible even when it's set - you don't need to be at precisely "half" of the part you're casting when making a mould, you'll still be able to get the part out of you go partially over curves.

 

[undertaker]

Great stuff @Stoof! If you would permit me to add a couple of my own drops of wisdom:

Top tip 6 - If casting in Milliput, get the part out before it is completely set and still a bit flexible (after ~8 hours at room temperature ~19C). Trimming the flash and any errors with a knife is a lot easier before the Milliput is rock-hard. Also, the fine parts can be brittle, so having a bit of flex when you pop it out of the mould helps keep it in one piece.

Top tip 7 - Get a wooden toothpick and use it to poke that Milliput into the recesses of the mould. Smooth it off with your finger. Then use the side of the toothpick to scrape away excess putty around the edges of the piece before pressing the two halves together. Have some water nearby to dip the toothpick in and keep it slippery. If you prefer metal tools, it helps to rub them on a damp sponge before touching the Milliput, 'cos that stuff is very sticky.