Thursday, August 7, 2014

Canopus: Fitting the Boiler

After a fair amount of filing and fettling I thought I was happy with the boiler, smokebox and saddletank castings. Turns out it still wouldn't all fit together properly.

If you remember back to the previous post on Canopus I mentioned in passing that the smokebox needed a hole drilling and tapping but that "this was easy to do as there is a dimple in the casting to aid correct positioning". Unfortunately I didn't actually check the dimple was in the correct position before drilling and tapping the hole. It turns out that the dimple wasn't correctly positioned on the casting so when the smokebox was screwed to the footplate it was about a millimetre to the right of centre (when viewed from the front).

Now a millimetre might not sound like much but on a model that is only 26mm wide it is quite a lot. What is more annoying is that I didn't spot the problem during the numerous test assemblies I did, only after the parts were glued together did I spot that they were out of line.

At first I thought I could live with the problem, but the more I looked at it the worse it seemed. Fortunately it was easy to break the two superglued joints to allow me to separate the parts and refit them. Unfortunately there was no easy way of moving the tapped hole in the smokebox casting. If it had just been a hole I would have filled it and drilled a new one, but I wasn't sure if that would work. Instead I slightly opened up the hole in the footplate that the screw passes through allowing a better positioning of the part; I will need to do the same to the matching hole in the chassis at some point.

With the boiler fitted, I attached the chimney and smokebox door handle (both of which are nice brass castings) although from these photos there is clearly still some work to do to hide the join between the chimney and smokebox, but I'll do that when I've finished the rest of the body. Currently the saddletank is only rested in place as I need to drill holes in it for handrail knobs etc.

It may have taken a while to get right but it is now looking like a really interesting little steam engine.


  1. You really have a great deal of determination and patience. It looks as though it will all be worth it in the end though.

    1. In retrospect fitting those parts was easy compared with the part I'm currently fixing after I managed to break it. Drilling 0.45mm holes into tiny cast brass fixings is a slow and tedious process!