Making Spare Parts

Sometimes you lose a part, or break one, or need it for a special project.  When that happens, sometimes you can cast a new one.  It takes a second copy of the missing part, some model clay, and epoxy resin glue.

In this case I needed some loaders hatches for an Abrams tank turret.  The Boley Abrams does not come with a loaders hatch!  So I borrowed one from a Roco Minitanks Abrams to act as the master part.  Take a small piece of modelling clay and flatten it out to act as the part mold.

The original Roco turret loaders hatch was placed in the center of a piece of model clay.  The detailed side is face down.  This technique only makes pieces that are detailed on one side.

This technique is called a press mold.  Because you press the item to be copied into the clay, so it is just below the surface of the clay.

Using a toothpick, carefully remove the part from the mold.  Try not to disturb the clay.  The clay does not harden so you can use it over and over again.

Again, using the toothpick adjust the clay to correct any imperfections in the mold.  If you don't like the result, ball up the clay and start over.

This is the epoxy I use but other brands are fine.  Casting resins work very well, but this is cheap and most model builders have this or something similar on hand.

I squeezed out a tiny amount of parts A & B onto a piece of aluminum foil.  Using a toothpick I mixed up the epoxy until it was a uniform consistency.

Use the mixing toothpick to transfer a bit of the epoxy into the mold.  Over fill the mold a little.

After waiting until the epoxy is dry, five minutes epoxy does dry that quickly, take the molded part out of the clay.  The clay will stick to the part.

Using your fingers pull off as much of the clay as you can.

Then use your toothpick to get the clay out of the nooks and crannies.  Run warm water over the part and use a toothbrush to get the last of the clay off the part.

Once the part is clean, you need to trim the excess epoxy and sand down the bottom flat.  This whole process takes less than about ten minutes.  I needed five of these hatches. I have about a 50% success rate of making an acceptable casting for each one I cast.  So I always make more than what I need. 

Here is the completed casting on the top of the Boley Abrams tank turret.  It turned out pretty well, but it's hard to tell with the clear epoxy.  The epoxy cuts and sands with your regular model tools you use on plastic.  It also uses the same primer and paint that you use on plastic models.  It can be glued to the plastic model with super glue or epoxy.

I used some of the Boley Abrams parts to upgrade five Roco M60 tanks to the General Dynamics 120S tanks.  It was a late Cold War version of the M60 / Abrams that never was fielded.

Here is the completed, painted and installed hatch.

The full version, Roco M60 hull top and bottom, and tracks.  Boley Abrams turret, gun, and side skirts, Roco Abrams machine guns from the details set, and the cast hatch.

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Mike Bunkermeister Creek


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