Part 17 by Vince Cutajar

Smoke module tested. Fan OK. Heater OK. Also tested smoke generation. Not very visible in the photo but it does produce smoke.

NEXRWAS TO transfer back some of the electronics in the tank and start clearing the table so that I can start work on the hull roof.

Started slowly putting in the electronics in the hull following the layout that is suggested in one of the photos of the Motion Control Module.

The Audio Module and the Motion Control Module are stacked on each other. The batteries are also stacked on each other. I put a rubber sheet between the lower battery and the battery tray and another one between the two batteries. With this configuration the batteries just miss the engine deck support.
Decided to continue with the mechanical part of the build. I was really looking forward to start work on the hull roof. The first thing I did was to fit the turret turn mechanism with the big bearing and gear. Everything went smoothly. I even put on the turret base to see how it looked and to check for fitment.
I also fitted the gear to the turret turn motor. Obviously I put the roof on the hull and tested the turret turn mechanism. Turns really smoothly.
Then I thought how about checking the fitment of the roof with the engine deck installed?

This is where I encountered a problem. The rear of the hull roof would not fit properly because the turret turn bearing was fouling with the engine deck support.

It seemed like that there should be a rectangular cut-out in the bulkhead (see red line in photo below) so that the bearing will fit in it.
I decided to cut the rectangular notch in the bulkhead. According to my measurements it needs to be at least 4mm wide. As I am lucky to have a milling machine, I milled it out.
I milled it 6mm deep instead of 4mm just to be sure. Using a drum sander in the Dremel I also touched up the semi-circle in the engine deck so that the hull roof will fit easier.
After the turret turn mechanism was sorted, it was the turn of the turret joint protector (bullet ring). Earlier I had made these (actually only drew them in CAD and then somebody else laser cut them) following the pattern of a real one. I drilled the holes in the roof using the segments as templates.
Fitted the speaker tray and fixed with some Velcro. Also fitted the speakers with some Velcro to the tray. I put them facing upwards. Did some more tidying of the wiring.
I started taking out of the boxes some turret components for deburring, cleaning and checking for fit. I immediately encountered a minor problem were the tongues of the turret front do not fit in the slots of the turret wrap.
Continued with the preparation process of more turret components. Some hand fitting was required but nothing major. This also helped me in getting a better mental picture of how things go together.
Test assembly of the turret. Lots of hand fitting required plus a good dose of patience. I have to admit it was frustrating at times. I align it on one side and lose alignment somewhere else. During those times I would drop everything and come back after a couple of hours which seemed to help.

Finally, after some compromises, I managed to assemble it to my satisfaction.

After I inserted the turret base I found that compressing the turret wrap was the best solution so that the screws would align with the holes.

Part 16     Part 18 here

the only free and the only weekly magazine for model engineers. 

Editor: David Carpenter