Nearly a week since any updates? Well, there’s not been anything of significance to report. There is a slight holdup with the brake gear, sadly, so I’ll have to roll with that until things resolve themselves. I won’t go into details, as there’s no need. There has also been a hiatus in workbench operations due to my insides deciding they didn’t like my food any more. That, thankfully, is mostly past, and I’m beginning to build up my strength again, albeit slowly. Why does it take longer to get back to full health as we get older?
So, rather than leave you hanging, and since the model is essentially within reach of handing off to the paint shop in a few weeks, I thought I would explain some of the smaller engineering tasks that went on a while back but mysteriously got ignored.
I wanted/needed the crosshead to be able to be disassembled should the need arise. I had hoped to allow for the tiny steel screw to be fitted on the inside face, and had countersunk the crosshead castings accordingly. However, the requirement to trap the driver's side crosshead in the slidebars with the air pump ram has meant I’ve had to compromise and insert the screws from the outside. I hope, once painted and weathered, they will be disguised sufficiently to look like the fitting I see on the photos. I think filling the slot with putty or plasticine will do the job nicely, while still allowing disassembly.
Aside from thinning the crosshead for clearance, the other task is to recess the leading crankpin nuts. These are the usual CPL type cast nickel silver ones. With the nut clamped in a pin vice, two tiny holes are drilled to allow me to insert the tips of a pair of needle nose tweezers so I can tighten them up on the pins, and a suitable tap run through the centre hole.
@simond has made a little spanner for this job, I believe. Sadly, my ability to drill holes correctly to suit a tool I might make doesn’t fill me with hope. The twin-hole idea is one that
@Dikitriki has explained in one of his many, incredibly helpful workshop threads. If I can muster the strength, I’ll attempt to find one and provide a link at some stage.
The hole in the coupling rod is recessed: I haven’t sourced a fancy D-shape cutter to achieve this, so I carefully run a 45 degree countersink in the hole to provide a little depth. The nut is then carefully filed until it’s slightly proud on the reverse, and then the front can be filed to give even more flushness. It's easier to do than explain.
(As I don’t really want to build many more locos, I don’t think acquiring a recessing bit will be worth my while now.)
I drilled 0.5mm holes in the tops of the coupling rods, and inserted NS wire to represent the cork bungs on the oil pots. It’s a detail I usually neglect, but as the cast connecting rods had this detail I felt duty bound.
The list of things to complete is getting shorter. Around the chassis, aside from the brakes, I have to fill the backs of the wheel balance weights and finally epoxy the crankpins in their holes. Around the bodywork, it’s mainly cab details that can be left until post-painting. One thing I will do after I stop futzing around here is to rework the cab roof fixings. I’ve never been quite happy with my original scheme. Although it worked, it wasn’t easy to do properly, and might risk damage to paintwork later on. I will probably go a more traditional route.
Right, even typing this has tired me. I think a few minutes' lying down will be necessary.