30 April 2012

Hot Glue Molding and Scratchbuild Micro-Armor

Last post I introduced my new rules for sci-fi tank combat and mentioned scratchbuilding some fighting vehicles for the playtest.  I got started today and by utilizing some new techniques, namely molding with hot glue and casting with plumber's epoxy, I was able to finish the first model in a single day.  Fast yes, but as you can see by the pictures below, very crude.  Still, I'm posting here in tutorial form so others can make their own judgements without having to spend the time and materials themselves.

Crude, but obviously a tank


First I made impressions in Sculpey polymer clay of the left and right tracks and wheels, the main hull, and the turret.  This is the true sculpting part and I can't offer too much advice here without sounding esoteric...you just have to visualize what the positive image will look like while making these negative impressions.  After the impressions were complete I put barriers around the impressions and filled the whole area with water-putty, creating a bas-relief-like slab with the tank's components jutting out.  This is exactly how I make my spaceships now.

Tracks and wheels

Hull

Turret

Blurry shot of putty masters


The putty cured and I removed the slabs from the polymer clay.  Normally at this point I make a mold of the raised part using naphtha-thinned silicone caulk.  Tonight however I decided to mold with hot-glue.  I neglected to get any pictures of my molds, but they were moderately detailed though nothing like silicone.  The huge benefit from hot-glue molding however is the short preparation time: 10-15 minutes for the glue to cool versus the 24 hour cure time of silicone.

Since I could tell the molds didn't have the detail I wanted, I decided to continue experimenting, this time with casting material.  Keeping with the theme of speed I mixed up plumber's epoxy and pushed it into the glue molds.  Plumber's epoxy may be grainy, but it cures rock-hard in 5 to 15 minutes.  When the parts cured I pulled them from the molds.  Due to my lack of mold release on the putty masters, the hot-glue molds had putty in them, obscuring some detail.  Still the parts obviously represented a tank, so I assembled them (with more putty) and added the gun barrel.  With a paint job and about a meter distance from the observer I don't think it would look too bad.



Although the model above is extremely crude, I'm pleased.  I know that the tank's details look poor because of the molding and casting materials, and I know from my spaceship building that the silicone-resin combination, in contrast, preserves very sharp details.  And although the blurry picture of the masters doesn't show it, the putty sculpts are nice and sharp.  I've never made ground vehicles before, only spaceships, but the techniques carried over nicely.  So hopefully I'll find some time in my schedule to make another master (I want bigger tracks), make a proper silicone mold, and cast in resin.    

5 comments:

  1. Almost like a 'rapid prototyping' technique... very interesting. Thanks for showing us this.

    Colin

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  2. You can try Gypsum products such as dental plaster....

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  3. Great job. Your method of sculpting the tank is very clever. I would have never thought to do it that way. I think it turned out pretty well.

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    1. Thanks Chris. I'm not skilled enough to simply sculpt it out with epoxy like the professionals, but I've found at these smaller scales I can "fake" it with the impression method.

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  4. This reminds me of Oyumaru, look it up. Some kind of "plastic" you heat in water, and then press against things you want to copy. Then you fill the moulds with epoxy and let it harden. So fast as hot glue, but reusable.

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