Entry posted by D869
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In the previous installment the etches for the D600 bogies had just arrived in the post leaving me wondering whether I could actually build a bogie from them...
Thankfully it turns out that I can 
Some of you will have seen the partially completed bogie at the AGM on Saturday (and a jolly good day it was too). I had hoped to have two bogies built, painted and on the loco before Saturday, but the etches arrived rather later than I had planned so it was too big an ask. Instead D604 had to go on show (again) with its class 47 bogies but the competition judge still liked it enough to award it a pot, as did the assembled members. I'm now glad that I was talked into entering it - thanks Chris.
I'm now progressing at a rather less hurried pace. The first bogie is almost fully assembled. Here's a picture of it sitting near a photo of a rather bigger version.
I was worried about a lot of the issues in the various 'how to' guides - mainly whether the thing would actually prove possible to build. Actually most of the things I was worrying about turned out just fine. Partly this may have been because I printed the most critical artwork out at double size and stuck it to some 0.5mm card so that I could mock up the parts and test things out in three dimensions before sending the artwork off to PPD...
The main things that went wrong were those things that I didn't think about while drawing the artwork. I made the classic finescale mistake of scaling chassis components from the prototype and forgetting that our wheels need rather more clearance than the prototype ones, particularly to avoid short circuits. This was solved by building the sideframes using five layers instead of the six I had drawn. Then for some unknown reason while designing the front end of the bogie I temporarily forgot about the big lump of Farish plastic that was going to be sat in the middle of the bogie and put some bits of metal where the plastic would be and had to resort to chopping bits off the etch to rectify the problem. My test with the card didn't pick these problems up because I didn't have a twice real size Farish bogie to try it on.
Finally, a photo of it under D604. Sorry about the flash bounce (and the slightly non-level body) but at least you can see all of the springy bits this way. You can also see that the Farish bogie wheelbase is just a tad short. I knew about this beforehand and compensated by doing the etch to 2mm scale rather than 'N', but I didn't want to mess up the dimensions any further. It's been a lot of work to get this far, but I'm rather pleased with the results.
Update: I've been puzzling about the space between the back of the bogie and the battery boxes. There is stuff going on in there on the prototype but no detail is
visible in most photos. The rear air cylinders were also 'whereabouts unknown' - I was pretty sure that they should be there somewhere because they were present on the EM2 version of the Ivatt bogie and also on the 2 axle variant used on the class 22.
I think that I've now figured out what's going on - the back end is not (as I guessed when drawing the etch) a mirror of the front. The air cylinders sit on top of the transom facing backwards and tucked well underneath the body. They are just visible in the NBL factory photo if you look very hard. They should hide the retaining clip nicely. There is also a vertical rocker shaft outboard of these that I'll represent with some brass rod.
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