On Friday, Andy Malette hosted me for another work session on the CNR 2-8-2 project – and we tackled a major modification: the smokebox front.
Our donor engines are USRA-designed light Mikados from Overland Models, which feature a smokebox front held in place with 20 dogs. Depending on the class of locomotive (and possibly the builder) Canadian National Railway steam engines featured either 10 or 12 dogs on the smokebox front.
We tend to notice these things, so it was obvious that the old dogs would have to come off and be replaced with new ones in the proper pattern. In this case, I would need 12 dogs – which means I couldn’t even cheat and simply grind away every other dog on the USRA smokebox front.
The Overland Models smokebox front is removable, but the dogs are cast as part of the face. So the easiest way to remove them was to turn them off on a lathe. I worked with very light passes, checking my progress frequently until I was happy with the results. After using the cutter, I finished up with progressively finer grits of sanding paper until all evidence of the dogs had disappeared. (This process also removed a portion of the hinges, but they will be relatively easy to replace with brass strip.)
Once the old dogs were gone, it was time to install new ones. Andy has some dogs cast by another friend of ours, but I would have to drill the smokebox face to accept them, then solder them in place. We moved the smokebox front from the lathe to the mill and added a 12-position indexer to evenly space the holes:
I started with a centre drill, then carefully drilled for the dogs, adding cutting oil for each hole. The last thing I wanted was a broken drill – Andy said he’s ruined a couple of smokebox fronts that way – and I’m pleased to report I drilled 12 perfect holes with no incidents.
Andy then locked the smokebox front in the vise and demonstrated how to solder these tiny dogs into place. He did the first one – I did the next 11. A minimal amount of flux, heating near – but not on – the dog, and a light touch with a thin length of solder on the side away from the heat was the key: Done right, the solder would melt onto the face of the smokebox than draw itself under the dog.
Here’s a composite photo showing the smokebox front, before and after the alterations:
I think it was definitely worth the effort.
As part of this work session, I also added a drain pipe to the feed water heater, which I’d somehow missed during last week’s piping session. It’s the smaller pipe in this next photo, just ahead of the large exhaust pipe:
There are still a few details to address – including the various appliances that mount on the smokebox front. But I now feel confident that CNR 3737 is heading towards the paint shop this year. I’m really pleased with the progress made so far this month and look forward to the next session…