The BOT8Fs Part 2 from Irwell serendititiously has a couple of excellent close up photos of cab doors on 48133 and 48131. I'd turn them into art prints and hang them on the wall if I could. Browsing lots of 8F photos reveals that there were several minor variations of the cab doors, mostly to do with rivet positions and the extent of beading (if it is really beading, it looks like wooden wear strips in some photos) around the edges. Since I've no idea which details were present on 48142, I've chosen a combination that I'm happy to model.
Comparison of drawing dimensions and photos with the etched kit parts persuaded me to make some replacements from scratch. The signature features on the doors are the hinges. They're very chunky and held together with battleship rivets. The first job was to sketch the hinge parts in CAD and establish sizes and rivet positions. Since they're such small parts there's not chance of adding rivets accurately to finished hinges. Therefore several hinge rivet patterns were pressed into a scrap of NS using the (t)rusty GW rivet press. It doesn't get used much, and hardly ever using the graduated slides, but this time it was just the right tool for the job. It doesn't take many rivets before I start wondering if there's a better way. And waddaya know, there's dude in the US who has actually made a CNC rivet press...
Computer Controlled Rivet Embossing Machine
Door blanks were cut from more NS (0.27mm I think - didn't measure, just felt about right), and we have some parts to start work.
The cutting of hinges from the pre-rivetted strips was a trial, and you need several of them. I made a few spares of course - there'll soon be enough parts in the vacuum cleaner to build another loco. The vertical strips appear to be a half round section, and they were made from brass wire filed half flat. All the fussy soldering was done with the RSU and tiny chips of 145 degree solder. Here's one door compared with the kit parts. Scribe lines are regrettably heavy, hopefully I can buff them out.
There's some vague provision on the kit parts to hinge the doors using (I assume) wire. They can't be rigidly mounted to the cab because the rear edges will bear on the tender (...yeah...the tender eh?...) at some point and there will be relative movement between loco and tender to accommodate. Low wattage light bulb moment - I used some phosphor bronze strip behind the doors to act as springy hinges. The strip is only spot soldered at the rear end and the middle of the forward door section. That leaves a reasonable length of strip free to flex. Sorry about those lower door rivets - freehand innit?
I discovered at this point that the hinge positions I'd estimated were a little at odds with those of the kit. Since there's an etched notch in the cab wing plate for the door hinges I need to make a wing plate overlay to cover them up.
Having fitted the wing plate overlays (and neglected the opportunity to add some missing rivets to them before soldering - duh!), the door assemblies can be fitted to the cab.
The downside to this approach is that the hinge strips show inside the cab. Hopefully they won't be too sore thumb when the loco's painted and the crew are drawing attention to themselves. They spring inboards and return quite nicely with little force needed. Another potential problem is that the loco body now needs careful handling to avoid damaging the door hinges. There's not a lot left to do on the loco body now, so hopefully they'll survive.
Bonus material - maybe.
Files. One great distraction activity, when I'm faced with a modelling task that I'm not too enthusiastic about, is wasting time on You Tube pretending to look for useful information. For once, at least, it bore fruit. I came across some horological wisdom on files and filing here...
. Since we tend to do a lot of filing it's worth a watch. Something I'd not thought about before is 'safe edges' on files. Not
safe as in 'occupational health & safety', but
safe as in a surface that won't cut. Armed with that nugget of information, I took the small Vallorbe escapement file out the the workshop and ground one of the edges smooth on the cutter grinder. Heresy, I know. It made filing some of the hinge internal corners a whole lot easier. Rubbish photo, but you get the point. Recommended.
Flux and soldering cleanliness. I pay a reasonable amount of attention to cleaning up parts before soldering. Wet & dry, scratch brushes, wiping clean with IPA, and all that. I use Fluxite paste flux for a lot of work - stays where it's put, good fluxing action and is easy enough to clean off afterwards. The tin of Fluxite I have was inherited from my late father, and goodness knows how long he'd had it! I remember it being part of his tool kit when I was a little boy. It occurred to me that the murky dark brown paste in the bottom of the tin was actually quite filthy. Filled with grit, solder blobs, dust and 60 years+ of accumulated workbench detritus. I guess I'm emotionally attached to the tin, so rather that throw it away I cleaned it out and refilled it with fresh paste from a new tin of Fluxite (they still make the stuff). Surprisingly fresh Fluxite is a pale yellowy colour, not a dark brown. Unsurprisingly fresh, clean flux works much better than old, mucky, degraded flux. Who have thought it?
RSU electrodes. I have an old Exactoscale RSU. Bought it on an impulse at a show a long time ago. Less than full price, and quite possibly Bernard Weller's prototype unit! Utterly unsophisticated, but it works well. I also acquired a small plastic bag with a dozen or so copper coated carbon electrodes for the probe. They don't get used up very fast so they've lasted a long time. They're not the sort of thing you come across when you're out shopping, so when I stumbled across some on eBay I thought I'd restock. The eBay electrodes turned out to be a revelation. They're much denser and harder that the Exacto originals (closer to the charcoal end of the spectrum!), and that makes them much easier to shape to a point and much less prone to crumble in use. It's made soldering of tiny details much easier with a properly pointy point. Wish I 'd discovered that years ago.
Hopefully 48388 will be in part 3.
