OO9 Ruston Proctor part 5 - couplings, a new chimney, and a repair.

Couplings on OO9 locos are always going to be a compromise between being prototypical and functional. Of course using the usual Bemo type of couplers limits our choices, but to me choosing the right style can either make or break a loco. I feel that the best aproach is to try and follow the protoype as closely as possible, within reason. Several styles are available from the trade, in whitemetal, 3D printed and etched, but nothing that comes close to the type fitted to these locos. To my knowledge two types of coupling gear were fitted to Ruston Proctors, either two dumb side buffers with a pin and link between, or a central buffer with a hook either above or below. In either case the buffers are formed from flat bar.

I decided to make up a central buffer from scrap etch. First job was to find a piece of etch with a suitable section that can be cut out (to save a lot of filing...), like the section marked out in the photo below;

Then I made a sketch of the coupler followed by a rough prototype, to prove the design. After refining the design its simply a case of filing the off-cut to size, drilling a couple of holes (.4mm), then bending the brass to shape. For the ninety degree folds I followed etched kit practice by using a triangular file to make a fold line. The curved bends are formed with round nosed pliers. Here's one made up and the other still flat;

I've started using a pair of spring dividers for marking out, as seen in the (very poor) photo above. That pair came from China via eBay, and are as cheap and nasty as they look. Still, they do the job. I've replaced one point with a piece of brass rod, so they can be used as odd-leg or Jenny calipers for marking out a line parallel to an edge.
The couplings have been chemically blackened with Birchwood Casey Brass Black, which has taken so nicely that I'm going to leave them in that state and fit them after painting. Here they are blu-tacked onto the 'beams;

Note the scrap couplings in the photo above, I don't always get it right first time...

I've given the body a light squirt of acrylic car primer as I've started to smooth down the print, using rubbing sticks, files and a three-sided scraper(!). Whilst doing so I managed to damage the cab rearsheet. Handles are cut-out either side, which look far neater than the handrails fitted to most locos. One the right hand side I managed to break the handle, the print being quite thin and fragile in this area. My solution was to file away material above and below the damage, and then cyano a piece of brass rod into the filed area, which in turn is blended in with a file;

Both sides don't quite match, and a little filler is needed to blend the repair in further, but hopefully it won't look too bad once painted. Frosted Ultra Detail is an odd material to work with, its quite brittle and hard, feeling more ceramic than plastic. I'm not sure that I like the stuff.

Printed boiler fittings never look right to my eye, even if they're the right shape there's always an issue with surface finish, so I turned a new chimney on the Unimat. Actually I turned two, as the printed job looked pretty good I made a straight copy, but when I compared it to photos of the real loco it didn't look at all right, so I turned up a second chimney after making a sketch from the drawing in the Parkinson book. Its actually quite a subtle shape, convex above the lip and concave below. Another lesson learn't, when making new parts don't automatically copy the part thats being replaced but go back to the prototype. Here it is fitted;

Of course it isn't really a chimney but a vent for the engine cooling hopper.
To improve the running I've replaced the .315mm phospher bronze pick-up wire with 36swg (.193mm) wire, which obviously is springier.

The next job is to sort out axleboxes etc., as well as finish off the interior.

Paul.