Saturday, February 1, 2014

A Primer On 3D Production, Part Four


This is a primer for folks thinking that digital sculpting and rapid prototyping will magically solve their problems when it comes to making their own miniatures company.

Bottom line is: it won't.  I've stepped on a few land mines in the past and can show you one particular path that won't result in severed limbs and a broken career.  Mostly.

Here are parts one, two, and three.

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This is part four, mass production and molding (or "moulding" for you UK types).  There are two major categories of molding:  rubber molds, and metal molds.  One is usually formed around an existing master, the other is a hollow space machined into blocks of material.



Injection molding, like the styrene model kits you find at hobby stores, is a whole level of madness unto itself.  Mark Mondragon, with his stunning success with the reformed Wargames Factory, the gents who run BrickArms, or the blokes over at Renendra could all address that subject far better than I.

Here's a neat little guide to "guerilla CNC machining," if you're insane enough (like me) to try and do it on your own.  I'm at the very start of the learning curve, but hope to make progress someday.  


No, instead, we'll deal mostly with rubber centrifugal casting, or "spincasting."

If you're a little guy, just starting out, I would advise you that it's better to start in rubber molds and spincasting, and build your business empire from there.

Injection molds cost tens of thousands of dollars.  Rapid prototypes and rubber molding is in the high hundreds, low thousands, at least starting out.

Here's a link on how it's done.

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So, on we go.

There's a reason, beyond it's "just what you do," why manual sculptors use two-part epoxy putties (green stuff, brown stuff, ProCreate, Magic Sculpt, etc.) and metal parts in their master models.  

The original sculpting putties were made to be plumbers putties, with construction and other hard-environment uses as the purpose for their formulation.  They're tough and flexible, and can take a moderate amount of heat and pressure.

I often heard Reaper talk about "greens," as completed hand sculpts are known, needing to withstand 300 degrees fahrenheit and crushing pressure for mastering or production molding (you're basically forming a tire around your sculpts).  

To do that to the older wax or plastic rapid-prototyped masters would have just resulted in boiling smears and puddles.

Photopolymers and resins melt quickly, and snap under the slightest pressure.  That's changed.


I'm not a caster, leaving that arcane art to those that do it far better than I, but I know that the new Nicem Green rubbers ( http://www.contenti.com/products/spin-casting/179-389.html ) are able to vulcanize at lower heat, without destroying the fragile master (which, again, isn't so fragile anymore).

Both of the previously-mentioned service bureaus  in other blog posts (Moddler and VisionProto), or more specifically, their Perfactory machines, can now produce high resolution prints in materials that can take up to 280 degrees fahrenheit.


This enables you to skip the process of "translating" the master to something that can withstand high-temp vulcanizing.  During the Reaper CAV days, we used to lost-wax the masters into silver, and these became the production masters.  Here's an old page of how it used to be...

Detail gets lost, casting flaws have to be corrected, and your final product is another generation away from the highly detailed vision you started with.  The new materials combined with the new rubbers lets you go straight to production molding, if you're going to do small runs.  Your caster should make this call, though, since they are the experts in this regard.

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As you may of may not know, most small companies in the miniatures business don't do their own casting. Most of it funnels through a handful of contract casting houses that also put out their own products.  I mean, do you want to sling molten metal, or develop resin allergies?  The metal part is fun (I got to run the spincasters once at Reaper), but I dislike potential chemical reactions.  Best left to the pros, either way.



Reaper, BTW, contract casts, and has helped many small companies (and some large ones) fulfill their production needs.

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As far as what material to cast in, that's a mixed bag.

Resin can be used in large model parts, or in those requiring intricate levels of detail, but any mistakes or miscasts are usually lost to the trash pile.  Molding is easier to make, usually, but wears out faster.

Pewter/white metal parts can be cranked out cheaper, but are harder to mold, usually.  Any screwed up parts can be thrown back into the melting pot, though.

Both materials are subject to commodities fluctuations.  Tin and lead move up and down on the metals market.  Most resins are petroleum derivatives, and ride the OPEC roller coaster.  It's maddening.

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Alright, story time.

Like picking a sculptor, picking the right caster is a crucial choice.

I'll illustrate with an example from my own past.

When I had the license from Reaper (Thansk Ed!) to produce 1/60th scale CAVs, I went with the recommendation of Nick Tompkins from Epicast, who lived in Vegas at the time. Great guy, Nick Tompkins.

Nick told me of a guy in named Dave, with whom he had worked with in the past when he was part of Armorcast.




I contacted Dave via telephone, worked out the terms so that both parties were happy, and hired him for the Dictator and Despot kits (a large mech and tank, respectively).

Great castings, parts were sorted ahead of time, and he was a dream to deal with.

A layout of the kit by Inso, I believe.  Notice the pale areas he had to fill in to repair it.



I then did my third kit, the 1/60th scale Scorpion, using a caster I met off a forum. I figured, why not, his stuff looked legit, he said he did major works for museums, and took a shot on him.



It was a disaster. The resin was runny and stank, there were mold lines through the worst possible places, and he dropped out of sight with my rapid-prototyped master model.

I ended up selling the lot as "Factory Seconds" (my catchy marketing phrase for "junk"), and curled up in a ball for a few years.  It was the end of retailing, for me, and I focused instead on just sculpting.  Maybe he did me a favor, I don't know.

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So, sad sad story aside, when contract casting, make sure you realize it's just as important a choice as picking the right sculptor, or the right target audience. 

 You can have the most brilliant product in the world, but if you can't reproduce it yourself, make sure you pick competent, experienced people.  Ask for past work. This is not amateur hour, and if the price is stiff, consider the amount of work it takes.  You usually get what you pay for.

So, that's my screed. I hope this helps. If you have any questions, feel free to ask in the comments. 

Best,
JBR
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