Looking good.

If you plan on casting this later on I'd suggest some slight modifications to the engine exhausts. The smaller tubes look very thin, so I have serious doubts regarding metal/resin flow. I think instead of tubes you might be better off making the engines as cylinders with a recessed half-sphere to suggest that they're hollow.

Are the plates covering the exhausts detachable?

Also: If you decide to make a metal version of this you should be aware of the difficulties casting something that has two "fat" parts connected by a longer thinner part Otterman had some problems with his Saltshaker gun carriage. It has something to do with the bronze used which cools faster on the thinner parts and risks cracking. I don't know if it was a similar problem that caused GW to discontinue their own Light Cruisers (It was something about them breaking the mould or something). Anyway: You might consider casting the body in two parts: Bridge/engine section and weapon/prow section, with a peg in one end. Of course this may not be a problem if you decide to cast in resin.

Anyway: Just a few random thoughts. Keep up the good work  

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I beleive it was they caused too many bad models, white metal being unsuitable for long flat sections so not coming out right.

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Thanks for the suggestion, I'll convert the hollow cylinders with this.



I was wondering on how much parts to divide it in. I though Engine section, Forward section, and the middle piece for the main body (3 parts). Then 1 piece for the horizontal "wings" support, the two fins and the armor covering the exhausts. It makes a lot of pieces, but each of them is more simple geometrically speaking, si I thought it will be easier to mold.

Concerning metal & Resin, I thought to make the "final" model in resin, and masters in Bronze/Metal (I think Otterman works like this). If you have any piece of advice about this, don't hesitate to help, I'm a bit lost concerning this phase.



Each time I order at Forgeworld, I desesperatly say in the "advice" field: "make molds for the Armada Light Cruisers"

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Some more details. Just managed to get 10 minutes to work tonight:



And the thingy on the fins:

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I think E&C recently had a bit of success casting resin straight from the rapid prototype piece.

Certainly. You can easily make moulds from the blue rapid prototyping material for resin casting.

The bronzing is only necessary for metal casting. This is because the vulcanization process when making the mould exposes the master to high temperature and pressure. This will cause some materials such as plastic to melt. To make a rapid prototype master that can be used for metals you first need to print a standard "blue" prototype. This prototype is then covered in a type of clay or sand awith a small feeding channel. When you pour molten bronze into this, your rapid prototype will evaporate inside the mould and be replaced with a bronce replica. This bronze is then sturdy enough to survive vulcanization for production casting in white metal or lead.

Resin moulds obviously don't have these limitations. No pressure or heat is involved when making the mould from silicone rubber. so you can make moulds of just about anything. Obviously this is also much cheaper. What it really boils down to is werther you prefer metal models to resin ones.

Resin pros:
Cheaper to set up
Holds detail better

Resin cons:
problems with air bubbles (Unless you got a vacuum chamber)
less durable than metal.

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Thanks for the informations



Just, what do you mean "less durable than metal" ? About the mold or the model ? And about the bubbles, I'm looking for little manual vacuum chambers, they are not so expensive ...

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Vacuuming the silicone before moulding is more important than vacuuming the liquid resin, as any bubbles in the actual mould will be replicated on all casts. Vacuuming the resin in the mould is useful for getting rid of bubbles, but casting under high pressure in a pressure pot is much more successful for this.

A manual vacuum pump will likely not be powerful enough, as it has to get down to near vacuum in order to be successful.

The main advantage of metal casting is that you can effectively pay someone else to do the casting for you, as resin casting is very time-consuming. The start-up costs for resin moulds are far lower though (assuming you don't include the cost of a vac chamber/pump etc).

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He means the eventual model will be fragile, as compared to a more sturdy metal model.

I'd add 'notably higher cost to produce per model' to the list of resin cons, and 'cheaper for large production runs' to the metal pros.


As Zombocom says, you need near vacuum to pull bubbles out of a silicon moulding material.

To remove the bubbles, you need to 'pull' at least 29 inches of mercury. To give some context to that figure, ~29.8 is total vacuum, and 1 inch is standard atmospheric pressure at sea level (I think).

Until you reach that level of vacuum, you'll only remove about 1% of the bubbles.

There are some techniques you can use to create a mould without using a vacuum chamber, such as the 'high pour', and always pouring to the lowest point in the mould but they're still not going to remove all the bubbles, especially bubbles caught underneath objects inside the mould itself.


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I'd just like to add that I think it's awesome that people are now trying out CAD with space ship models!

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Mmmh, the main advantage I saw in resin was the lightness of the model. For a BFG model on a tiny plastic rod, it seemed an advantage to me ^^. I think I'll have to test both to see.



Mmmmh, I didn't know that. They can achieve this level of vacuum in the industry ? Or can a compressor help on a amateurish production system ?

Also, I heard vibrating tables can help (like the vibrating rod used in concrete industry), is it true ?

From what I read to avoid bubbles:

- Pour the silicon from high, to have a very thin fillet (with a rod)
- Pour it on the lower part of the mold



I'm a bit afraid of metal casting, about the material required and so. For details, I was aiming (on the long term) at the precision of Forgeworld castings (thus the resin).




Greatly inspired by what the folks in the epic forum do . And I find the spaceships waaaay easier to model.

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By the way, here is the pieces layout I imagined. Any visible flaw ?

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Others have designed BFG ships on computer before y'know, though possibly just for art rather than printing (one can dream).

You guys not familiar with this?:

Inspirational lots  

Someone on warseer has also modelled a very detailled Black Templar Battlebarge. Given all the details, I think it's mostly for art

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I would try to keep the engine sections midpiece, and prow as a single piece if possible. It will just make the ship more durable and easier to assemble.

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