Turning back to the A7, I've a couple of weeks to finish as much as I can before the project gets boxed up at the end of the month.
So onward with the bogie.
Unlike the B1 this is a much simpler affair, primarily the LNER rebuilt version without brakes or equalising beams, and no, there are no plans to replicate that version I'm afraid.
At the moment no side control is built in, the bogie is very narrow with the axle boxes being on the outside of the frames, which makes my standard set up too large to fit. I'll not loose any sleep over it at the moment, besides the bogie pivot is actually a radial affair, rather than running in line left and right it follows an arc much like a radial truck; modelling that will be a challenge for sure, but I have some ideas bouncing around
As one can see a rather simple affair which uses individual axle boxes for springing and here in lines the bear trap. The Finney7 white metal LNER one is a very close match.....there's a couple of webs between the spring and horn cheek, which probably wouldn't cast for certain every time and the spring beam across the top is plain and does not have the split shaft to the axle box on......., certainly for development purposes, however it is tailored to suit the smaller 5/32" axles in the Slaters range.
Problem is, the correct wheel in the Slaters range runs with a 3/16" axle and in this case quarts do not go into pint pots. There are of course several options, ream out the castings to accept the larger axle, which will loose the locating lug on the rear and make the axle box walls quite thin
Develop new castings for the larger axle but again it'll have thin walls to the axle box so that'd probably need over scaling to compensate.
Try and get a 5/32" axle fit a 3/16" wheel, either open out the square hole in the wheel and ram in a 5/32" shaft or turn down a 3/16" to 5/32".
The last option is feasible mathematically but practically how much shoulder is left and is it sufficiently strong enough to hold the wheel square and tight, well as it happens, yes it is
There's very little shoulder left and the square hole in the wheel is beginning to show on the wheel boss, but it does all tighten up and hold firm and square.
The option does allow the test build to progress and use existing components, but for the future then lets hope Slaters see Nicks and my NER engines and perhaps run up a batch of NER bogie wheels with 5/32" axles
MD
- I assume the locating lug alluded to is a rim on the rear of the axle box which locates in the frame as it's not evident from the photograph since all the axle boxes are facing upwards. As suggestion going forward - is it worth turning one of the axle boxes face down so the reverse can be seen to enable those not always in the know to see what is being referred to? (This could also apply where there is more than one similar component in a kit)
