CNR 3737 :: ash pans and doors

Yesterday’s work session with my friend Andy Malette focused on the firebox of my CNR 2-8-2 project – specifically, the ash pans.

CNR 3737 ash pans and doors

The stock model has a pair of cast brass plates that run across the bottom of the firebox. These are screwed to the body of the model from underneath, as they must be removed in order for the motor slide into the firebox area. The plates project beyond the edge of the firebox but needed to be bulked up to better represent the bottom of the prototype. So I soldered some bar stock in place along the top of each plate, while they were still attached to the model – being careful to not solder them to the firebox wall. I then unscrewed the plate and shaped the bar on a bench grinder – working a little bit at a time and cooling the brass in a pot of water so that the solder would not melt and the parts separate.

Andy had prepared for the session by cutting some square tubing to create the frames for the four ash pan doors – two per side. I filed these to better fit against the curve of the base plates, soldered them in place, then returned to the grinder to finish them. A light touch was required, with regular checking to make sure I was grinding them so that their outside edge would be vertical when installed on the model. I finished these with a file.

Finally, when I was satisfied with the door frames, I made the doors themselves. These are simply pieces of styrene sheet cut to fit between the sides of the door frames, left long and soldered in place, then trimmed level with the top of the ash pan.

With these built, I test-fit the new ash pans in place. I had to gently bend some piping out of the way to get them to fit, but otherwise it went fine.

The last step was to add two blow-downs to the firebox, on the engineer’s side. These are spare castings from Andy’s CNR K3 Pacific project from a few years ago. I cut off a large discharge pipe on each. Then I drilled holes in the firebox side, soldered the castings in place, and added smaller discharge pipes that line up with the bottom of the ash pans. There’s a large hole from a removed casting that I’ll need to fill – the easiest way will be to simply solder a brass NBW casting or a piece of brass plate over it and be done with it.

There’s lots more to do, of course. But I have a busy couple of weeks ahead of me so we may not get back to the project until next month. Meantime, I’m putting together a list of details that I need to buy to continue this build.

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