This is a top 'box. I know it looks very simple but this is one of the best I have built in a loooong while. And that is a lot of model railway gearboxes.
Why is it so good ?
Well, first the etch folds up properly. The designer has worked out that at the corners you need to work out what overlaps what. A half etch rebate allows the construction of a square corner rather than the "fun" of trying to force two bits of metal into the same place.
The axles holes needed quite a bit of reaming to accept the bushes but far better that way than trying to etch holes the right size and ending up with something oversize.
Best of all though, the motor can go in with the worm gear fitted and the holes for the mounting screws can be used without alteration. A little allowance has been left to move the motor up and down to achieve the perfect mesh. In the last few boxes I've built these holes and the one of the motor shaft have had to be enlarged in all directions just to get the teeth together.
As this is for the 7mm Barclay, the whole arrangement is wide enough that the motor screws are either side of the worm so you can remove it while still in the frames.
Other gearbox designers take note !
Update: Apparently this 'box was designed on a napkin in a restaurant years ago when those concerned were slightly drunk. Other gearbox designers please note !
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