Building a "O" scale Brisbane FM Part 4

The only thing about this kit to give me any concern was the solid roof casting. It mates accurately with the two ends but being solid it was very heavy. As I intend to have a powered truck at one end only, a black beetle, I want to keep the finished model as light as possible. I have also found in the past that a top heavy model tends to be unstable and wobble excessively.

As I had the roof piece I decided to try to hollow it out. The roof of a FM was double skinned and the ceiling cavity was 6" in the centre and 8" towards the sides. So a final thickness of around 3mm to 4mm sounded about right. I set up the stop on my drill press to stop the drill 3mm above the table and then proceeded to drill dozens of holes with a 3/8" drill until the underside looked like a piece of Swiss cheese. Rocking the roof section all the time making sure that the roof was always supported directly under the drill bit. For the next stage I went outdoors with a sanding wheel in the dremel and removed all the web left after drilling then smoothed it off with a rough round file. This last part was very messy.

It's weight is now one third of what it was before after having removed 100 gms of polyurethane. It is now close to the prototype roof and it hasn't distorted with all that work. So I'm very happy at the moment. Everything seems to be going well. The interior roof photo is of FM 400 which is currently under restoration at the museum and has had the lining removed.