Author Topic: How to Cast Models.  (Read 4646 times)

Offline Lord Borak

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How to Cast Models.
« on: January 19, 2016, 08:02:43 PM »
Hello there chaps. If you have been following my thread then you should know that I'm currently casting up a load of models. For those of you who want to know how I do it and/or fancy having a go at it yourself, this is how I do it. Gav gave me pretty much all the links so thanks to him for those and for all the help and tips he's given me.

Before we start. These two links are very much worth a read. Everything I have gleaned has come from these two. (again, from Gav)

LINK  - How to cast models

Link - How to cast a light sabre


You will need....

Some Lego.
Some Silicone
A model to cast!
Three disposable pots.
A stirring thing (spoon is fine but make sure the Mrs doesn't have a fondness for it first!)
Some scales.
Instant Mould or Clay.

STEP 1:

Build your Lego castle. You don't want your model to be too close to the lego so give a space of about 10mm. Right, once you've done that you can move onto the first part of your mould. Now in the video and link above they use clay. I'm going to use Instant mould because It's what I have to hand. It's pretty good stuff, you just heat it up and it goes soft.

You want to make this as smooth as possible and with no gaps around your original or against the edges/corners of your 'wall'. Any gaps and the silicone will get underneath and cause you some grief. It's not the end of the world as you can cut this off later.



Once that was done I added to the Lego wall





STEP 2:

Silicone time. I use this stuff. It's good stuff and it's cheap. It comes in two parts that you mix together. The ratio is 3:100 (Catalyst/White stuff) So if you weight out 60grams of White stuff you need to add 1.8grams of Catalyst. It's best you do this in separate containers in case you make a mistake.



AS you can see, it's messy business so get permission from your MRs first kids.


Once you have the correct quantities mix together and mix slowly. Mixing it fast can add even more air bubbles which is BAD. VERY BAD. Pour into one corner of the mould slowly to avoid adding more air bubbles. Once poured in give it a few gentle taps to release any air bubbles clinging to your model. Now, in the video they use a Vacuum to get all the air bubbles out of the silicone. Now, I don't have one of these but from previous experience the silicone I use is very forgiving in that respect.



You may have noticed but I have placed a piece of plasticard underneath my mould. It's just in case some silicone leaks out.


This takes about 12 hours to cure but I advise you give it a full 24 hours before your de-mould..


Step 3:

Time to demould. Break away your Lego. You might get a fair bit of Silicone that has seeped into the joints but just cut them off with a sharp knife. I also use a pair of scissors to cut away the top edges as it curves upwards. You should be left with something like this..



Step 4:
Carefully remove your Instant Mould/Clay. Try and keep your original in the silicone. If it comes out you'll have to carefully put it back in. Making sure there is no gaps between the model and the silicone. You don't want the next batch of silicone seeping underneath.



Step 5:
Rebuild your Lego Walls.


Step 6:
Right, now to prep for the next layer of silicone. Here's a tip, I use a small piece of Cling film in one corner to separate the two halves of the silicone. This makes separating them a lot, lot easier. I then liberally apply this mould release spray




Step 7:
Now pour in your next batch of silicone. Pour it in one corner to prevent any unnecessary air from getting into the silicone.




Now wait for it to dry. Again, 12-24 hours.


Step 8:
Right, now that's dry you can dismantle your Lego wall. Cut off any excess silicon.



Step 9:
Now separate the two halves. The bit of Cling film should come out easily and give you something to get your fingers into. It can be tough to get the two parts apart but persevere.



Step 10:
Right, now it's time to cut holes into the mould in order to pour your resin. Don't make the holes too small. I've also added some air release vents to prevent air getting trapped in the mould.






RESIN TIME!!!!

I use this Resin. It's a two part fast drying resin.



Step 1:
First off, Spray your two mould halves with the Mould release spray - this will make it easier to remove your resin model and increase the life of your mould! Then you need to work out how much resin to mix up. This is a bit of guess work so you'll just have to keep trying until you get it right. It's always better to mix too little and add some more in than waste your resin! For this one I used 5grams of each part. It's best to weigh them out in individual pots incase you slip up. Mix well, mix slowly but don't dally to long as you only have about 1 minute before it starts to set!!

As this model is pretty tricky I put a drop of resin in each side of the mould. I pressed it into the hard to reach areas like the shoulder pads, the skull belt buckle and the corners of the cloak. This will stop the air getting caught here when you pour the rest of the resin in.




Step 2:
Put your two halves of the mould together and secure them together. I'm using elastic bands but be careful to not have the bands too tight. You want the mould to be tight enough so the resin doesn't escape but not too tight that the bands distort the mould. When you pour Resin in the mould do so slowly. You don't want to completely fill the pouring channel in case you trap an air bubble. It also helps if you rotate the mould a bit when pouring to help those air bubbles come out.




Step 3:
After about 45mins you can separate your mould and gently remove your new resin cast!




« Last Edit: January 19, 2016, 08:05:26 PM by Lord Borak »

Offline greenstuff_gav

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Re: How to Cast Models.
« Reply #1 on: January 19, 2016, 08:05:44 PM »
i put my electronic scales in a sandwich bag :)
i make no apologies, i warned you my ability to roll ones was infectious...

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Offline Lord Borak

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Re: How to Cast Models.
« Reply #2 on: January 19, 2016, 08:10:06 PM »
That's Genius......... I'm going to have to buy my wife some new scales as I have properly ruined hers!!!  ::)

Offline Alyster Wick

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Re: How to Cast Models.
« Reply #3 on: January 20, 2016, 03:43:08 AM »
So it's gotten to the point where, while this definitely looks like a pain in the ass, it's definitely within the realm of stuff I'm willing to do (God help me). Once you get so far down the rabbit hole there's no point in turning back.

When I finally get good enough at the actual sculpting I may well look into this deeper. The thought of being able to barter custom sculpted pieces fills me with an unhealthy warmth...

Incidentally Borak, your pieces finally arrived today! Look for me to post some later this week.

Offline Radu Lykan

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Re: How to Cast Models.
« Reply #4 on: January 20, 2016, 01:56:08 PM »
@lord borak, that's the same way I do it, from the Lego down to the same resin. With regards to the elastic bands not deforming the silicon, I use a bit of Mdf on either side, allows for tightness without deforming anything.

A community project just popped into my head, say 10 of us all made something original for inquisitor, cast 10 of it up and all do swapsies? So we would all end up with 10 new bits? Thoughts?

Offline Lord Borak

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Re: How to Cast Models.
« Reply #5 on: January 20, 2016, 03:30:05 PM »
Due to the size of my moulds I actually use old bank cards! To stop the moulds warping.

I'm happy with doing the swapsies  thing. Sounds like a good idea. If there are ten of us that do this that is!

Offline RobSkib

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Re: How to Cast Models.
« Reply #6 on: January 20, 2016, 03:35:34 PM »
Awesome, I love a good grubby step-by-step. I never trust a walkthrough that shows all the "stages" in perfect photoshop environments...

Any idea how much this setup cost in total?
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Offline seaglen

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Re: How to Cast Models.
« Reply #7 on: January 20, 2016, 04:25:24 PM »
Quote
I use a bit of Mdf on either side
- great idea.

Well this has certainly sparked my interest. Ive never really had much practice in sculpting, but am very excited by the idea of being able to cast up parts I already have. Down to the shops for me to pick up some lego and silicone...


Quote
ay 10 of us all made something original for inquisitor, cast 10 of it up and all do swapsies? So we would all end up with 10 new bits? Thoughts?
- I would be very happy to give this a go!!

Offline MarcoSkoll

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Re: How to Cast Models.
« Reply #8 on: January 20, 2016, 04:28:21 PM »
A community project just popped into my head, say 10 of us all made something original for inquisitor, cast 10 of it up and all do swapsies? So we would all end up with 10 new bits? Thoughts?
Works for me. I could do with something to light a fire on me on that front (I've had a casting kit sitting around for a few months now).
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Offline Van Helser

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Re: How to Cast Models.
« Reply #9 on: January 20, 2016, 06:04:40 PM »
I've been planing to cast more bases, but could be tempted to try casting components again. I've tried previously with awful results! This guide might help avoid the previous errors I made with my moulds.

Ruaridh

Offline seaglen

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Re: How to Cast Models.
« Reply #10 on: January 21, 2016, 01:33:07 PM »
Well, ive just been out on my break at work and picked up silicone/resin/instamould and mould release spray...
just need some lego blocks now to give it a go!


Offline seaglen

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Re: How to Cast Models.
« Reply #11 on: January 31, 2016, 10:18:37 PM »
FYI -  I've been playing around today and the first half of a silicone mould of one of the gene stealer cultists heads is currently curing!

Hope to make the other half tomorrow and so can cast up this rare piece for genestealer cults!!

Offline Alyster Wick

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Re: How to Cast Models.
« Reply #12 on: January 31, 2016, 10:23:36 PM »
Woah, genestealer cult packs (or at least components)?!?! Sign me up!

Offline Lord Borak

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Re: How to Cast Models.
« Reply #13 on: January 31, 2016, 11:02:02 PM »
I concur!!!

Offline Radu Lykan

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Re: How to Cast Models.
« Reply #14 on: February 01, 2016, 02:34:09 PM »
I think my brother in law has the gene stealer cult pack, didn't think of it but yep, mixing them with the borak cultists might be fun
Going to need moar silicone