Richard Stevenson
I converted two sets of SECR birdcage coaches a few years ago. These have a similar metal bar but a shorter 32 mm (8ft) wheelbase, so are not identical to those on the mk2f coaches. I was able to bend the metal bars sufficiently to just clear the faces of EM wheel sets. Shorter axles, about 25.25 mm long, were required. I have a lathe, so this job was no problem for me. It could probably be done, with care, by mounting the axle in an electric drill and using a fine file. The plastic bogie side frames were carefully trimmed back to just clear the modified metal bars, ensuring that the same amount was taken off each side and cutting round the locating pegs. These must be preserved to maintain alignment of the wheel sets. The existing hole behind each axle box was widened to accommodate the dimple which forms the bearing. There was a real risk of breaking through either side of the axle box, so I would not recommend trimming the side frames back further in order to accommodate longer axles.
The result was very free running coaches, which were demonstrated on the test track at the Didcot Skills Day in March 2020.
At the time I did not think that this method was suitable for a manual sheet as I used a lathe and it required very precise and time consuming work. It was recently suggested that there may be scope for “advanced modeller” manual sheets!
More recently, Neil Knowlden has developed a method using inside ball bearings and a 3D printed bearing carrier. This is the subject of a forthcoming manual sheet. A possible disadvantage for some is that the bearing carrier may obstruct the fitting of my favoured Alex Jackson couplings.
A possibility that I have not explored is to use an MJT bogie etch (other makes are available) with the Bachmann side frames added cosmetically.
In short, no, I do not think there is an easy way of converting these coaches.
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This reply was modified 1 year, 5 months ago by
Richard Stevenson. Reason: General reference to Bachmann coaches deleted