The etches work! Which is a relief. There were a few modifications that I had to make along the way and I had to learn how to put them together, the instructions supplied left a bit to be desired, but they work. There are bits that worked well, some mistakes and some overambition in places but nothing that couldn't be corrected. The photos are of the second bogie I built to which I made a couple of modifications in light of the experience of building the first. These changes are being included in a revised set of drawings along with one or two other improvements. Work on this is already well underway.
The hornblocks are the now standard High Level 2mm variety. I had the bright idea of actually using the Bachmann drivetrains to set the axle centres instead of a jig. Have no idea why I didn't think of that before! In the original design I intended to etch holes in the sideframes in order to pin the hornblocks in the right place but for some reason they didn't come out on the phototool. Hopefully they'll be there on the next lot.
Class 37 Bogie Etches 1.JPG
The primary suspension is a simple fold up affair that's riveted to the main bogie etch with 1mm brass rod.
Class 37 Bogie Etches 2.JPG
Everything is added to the bogie while it is still attached to the fret. It was always the intention to solder the hornblocks in place while the etch was still in the fret, indeed use is made of the outside of the etch to ensure the hornblocks end up square, and it proved to be best to attach everything else at this stage as well.
Class 37 Bogie Etches 3.JPG
Class 37 Bogie Etches 4.JPG
The bogie was removed from the fret and folded up. The circular bolster flange is a neat fit in a recess in the top of the bogie (this bit was really pleasing!).
Class 37 Bogie Etches 5.JPG
Once soldered in place the bolster flange was cut out to enable the drivetrain to fit. Secondary suspenion bearers were added to the top of the hornblocks. I made these from brass L section as the ones on the etch were too short. My error entirely! Springs are 9 thou guitar wire.
Class 37 Bogie Etches 6.JPG
The bolster plate was araldited in place and then the bit that wasn't needed was cut out using the half etched lines as a guide.
Class 37 Bogie Etches 7.JPG
Secondary suspension pins and coil springs were made and the bogies placed under the chassis. Some packing was added to the bolster plate and under the coil springs to bring things to roughly the right hight. The setting is a little low (intentionally so) and final adjustment will be made when the body is done so that everything can be set in accordance with the buffer centres. This picture illustrates something that I said elsewhere on this forum about bogies needing to be able to pich and roll. This is an extreme case (the ruler that the bogie's partially sitting on is 1mm thick!) but shows the pitch of the bogie in relation to the body. It was rather pleasing that the bogie coped completely with this cliff that I pushed it off and all the wheels remained firmly in contact with the table and the ruler.
Class 37 Bogie Etches 8.JPG
A Bachmann sideframe postioned in front of a bogie which has almost completely disapeared except for the bolster flanges and the secondary suspension (which is supposed to be there). Things have been designed so that when the top of the cosmetic sideframe is lined up with the top of the sprung bogie the axles centres are in the correct position in relation to the axleboxes. This means when attaching them you only have to worry about lining things up in one plane rather than two. Which I didn't on this occasion!
Class 37 Bogie Etches 9.JPG
Even with the process of rewriting your own instructions as you go along and the modifications needed they went together relatively smoothly. It's certainly been a learing experience but an enjoyable one. As I said earlier there are improvments to be made to the etches in light of the build. These should be completed this week then it's back to the etchers for the Mk2 version.
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