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post #2 of (permalink) Old 08-16-13, 05:01 PM Thread Starter
Subtle Discord
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An Introduction ~ Part 2

Ok then, where was I? Oh yes, the mysterious dark art of resin casting and how it has forever corrupted my soul... in a good way!

Now, I like scratch building, a lot. It's great to take an idea, design a flat template, and then turn that template into a three dimensional object. Problem is, scratch building is very labour intensive when you're as particular as I am. Larger things like vehicles may justify a one-off build that will take quite a bit of labour; they're large and not as prolific as troops, so why not? But, when you start getting down to doing smaller objects across an entire army, the idea of building say, six reasonably identical Havoc Launchers, becomes daunting. So I figured it may be a good idea to learn how to make some resin casting moulds...

I've always hated the Havoc Launchers provided on the Chaos vehicle accessories sprew. This is what I think a Havoc Launcher should look like.

I originally created my first replacement Havoc Launcher as a single solid object. It was one of my first moulds, so I was still experimenting. That early prototype worked, but it came with some limitations and drawbacks. If you resin cast, you quickly learn that your biggest enemy is bubbles. So, solid objects with no 'hidden sides' give you no place to hide bubbles. You can never get rid of all of the bubbles all of the time, but you can get rid of most of them. Also, if you cast an item correctly you can actually hide the rest. That is my constant goal - avoid or destroy all (most) bubbles. This kit is a perfect example; I've designed the moulds to intentionally cast the parts with the detail side down (As I try to do with all my moulds, when possible), so if any bubbles do form, they rise to the back/bottom of the part during curing, and will be hidden by the assemble of the kit. It's not genius or witchcraft, but I think it's clever. It doesn't work every time, but anything that saves a few casts from the reject bin is a good design philosophy.

With some logic, careful consideration, trial-and-error, and just a bit of luck here-and-there I worked out most of the kinks for making more complex resin casting moulds. It's one of those things that anyone can do, but it takes a certain knack to do it well. I've still got lots to learn, and I want to invest in more studio equipment so that I can start doing other casting processes. Currently I only use Pressure Casting (50+ PSI) for bubble eradication, but I also want to start doing Vacuum Casting for when pressure isn't the best solution, and that will require a proper Vacuum Chamber. Hopefully, all in due time.

I learned a lot making this little kit, but I wasn't sure if it was going to translate into larger items. Time to move up to making something... bigger...

I had this Land Raider kit calling to me, compelling me to make it Chaos, so who was I to argue? In these photos you can also see the Havoc Launcher prototype just before casting.

Did I mention it was a larger project? This is a picture of a mould, as large as the Land Raider itself, for just one (rather large) part in the final kit.

One thing I quickly learned making RTV (Room Temperature Vulcanizing) rubber moulds: Bulk matters. It takes some extra rubber, but in for a penny, in for a pound, I say. Making the walls of the mould thick ensures that the part casts without warping. Adding lots of the pictured locking-pins to hold the mould together is also key; A well made 2-part split mould like this locks together perfectly every time, minimizing mould lines and all but removing any mould slipping. Again, this mould cures the part face-down, so bubbles rise to the hidden back side. I put the same thought and process into all my moulds.

Designation: Loricatus Pattern Mk.I Heavy Land Raider

I think the investment in time and materials is worth it when you can make something like this, and completely transform the original Land Raider into a rolling icon of Chaos. (Look ma'! No spikes!) Ok, so clearly my ideas on making larger moulds were translating well to the larger objects. *In his best Montgomery Burns voice* Excellent! But there was still another challenge that I was trying to deal with at the same time. Enter the Proditor Pattern Mk.II Rhino Trim kit for demonstration.

This build was actually the first time I used one of my own resin kits to trim a Rhino. Up to this point they had all been scratch builds made of styrene and glued to the model as I built.

With the Land Raider I was worried about how large the parts are/were, with my Chaos Rhino Trim kits it was how small/thin they are/were. On the surface it seems straight forward to cast these trim pieces; they are nice flat-backed parts, after all. But, when you consider that they are only 0.8mm tall not including the rivets (I use two layers of 0.4mm sheet styrene for my trim/banding details) it makes the parts very long, thin, and delicate. How to get the resin into the moulds became a real issue because of this. After some research and a few practice moulds I adopted and refined a method of using a syringe to forcibly inject resin into the moulds. Without the added pressure to force the resin into the mould, I don't think I would be able to make these in my modest studio.

Proditor Pattern Light Armour Trim Kits - Left: Mk.II (Pictured here) Right: Mk.I (Pictured in Part 1)

So, even though these trim kits don't use that much resin to produce, they make up for it in the technical challenges inherent in their design. With what I learned here, combined with what I had learned from my other early projects, I covered most of the major technical issues I might run into for any of my current design plans. I was starting to feel confident enough to do something even more elaborate.

Started before I learned resin casting, I glued the scratch-built styrene directly onto the model as a scaffold to construct on, so I was never able to take it off to make moulds of it.

Unfortunately, all of my building has stopped my painting in its tracks. This Loricatus Pattern Mk.II Predator hasn't come any further than what's pictured here. I've finally started to get my studio back in some level of order and my painting area is active again. This beast should see some progress soon, along with several other monsters hiding in the shadows.

Even though I couldn't make a cast of these parts I really liked the design; with some further inspiration and some conversations with fellow gamers and tank-heads, I had a few other changes I wanted to make.

Naturally, now everything I build has casting in mind from that start, unless it uses parts that are protected in some way. As long as I make every part myself, (and don't build directly on or with any GW pieces) I'm free to replicate anything I build. Since I couldn't actually use this build for a kit, I was forced to make another from scratch.

More on that in Part 3...

"The old galaxy is dying, and the new galaxy struggles to be born; now is the time of monsters."

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