A 1/16 Post War Tank Turret, Part-6

A Report to the Cabal:

In the last few weeks Jake has finalized the inner workings of his gun mount and elevating system. So, time had come to bond the upper and lower turret pieces together so he could transfer that work from the roto cast polyurethane test article to the actual epoxy-glass GRP model piece. We elected to hold the pieces together with little brass straps as Jake laid in a length of epoxy resin saturated carbon cord. Believe me, that work went quicker than the time it took to write about it!

Last visit we also worked on the mantlet a bit and Jake did some rather innovative

work on the milling machine in support of that.

Here's a peek: To hold the two turret halves together, as the seam was bonded from the inside, we elected to use annealed brass straps. Before strapping the two halves together I had Jake rough up the inside edges to assure a good bond. Annealing is the process of heating and cooling a metal to change its physical characteristics -- in this case making the metal 'soft,' mailable, so it would bend easily. To soften brass you take it to a red heat and let it slowly return back to room temperature.

Jake attaching the straps to the perimeter of the two assembled turret halves. We used 2-56 machine screws. First you drill a hole and tape it for 2-56 thread in the upper turret half, install the strap with a screw, bend the strap around to conform to the bottom turret half, drill and tape a hole there, and secure that end with another 2-56 screw. Going around the perimeter of the turret enough straps are installed to hold things securely together.

The bond on the inside of the turret is achieved by jamming a 'rope' of carbon fiber strands into the seam and then saturating it, and the adjacent turret halves and seam, with West System epoxy laminating resin. Using a disposable 'acidbrush' outfitted with a brass tube handle permitted Jake to drive the resin into the inside seam between the two tank halves.

As the carbon is pushed into the inside seam with the brush, resin saturates it, holding it in place within the turret. Capillary action insures that the seam between the turret halves is filled with resin.

Jake using the rotory-table to achieve the evenly spaced holes that will be drilled into the face of this barrel-mantlet interface piece. To assure centering of the work within the chuck of the rotory-table we used a dial-indicator to find high and low spots -- adjusting the jaws of the chuck till we got nearly zero deflection as the work was turned.

Drilling on the milling machine with the aid of the a rotory-table.

Masters of the mantlet, barrel-mantlet interface piece, and the brass gun barrel mount next to the forward section of the turret.

Jake spends so much time here complaining how hard it has been to get the shape of the mantlet right -- what a crybaby!

Notice how he's drawn an inked grid-network on the mantlet -- this to help him assure symmetry of the facets and curves that make this piece so distinctive.