Having got the skip frames sorted it was time to root out those Gnomy skip bodies and do something with them. I decided to erase all the surface detail and the pivots on the ends. The pivots were sawn off and the stumps sanded off; the thickened rim on the sides was sawn off too, and the sides rubbed vigorously on a large sheet of sandpaper taped to the workbench to remove the rest of the raised detail.
Once the skip bodies were smooth the new detail went on. I glued 3mm plasticard strip around the rim of the sides and ends, and added little L-shaped reinforcing pieces on the corners. Pieces of 3mm L-section plastic strip were then glued along the sides some 5mm below the rim to represent the reinforcement that most types of skip had in one form or another (an example of which I had just sanded off).
Two views of skip bodies: l-r as bought, detail sanded off, and detail added:
The next step was to make the pivots for the tipping action. As I had made the top of the mounts in the style of the Rugga skip I had to shape the pivots accordingly. I took 3mm slices of 3mm plastic tube and glued them to 3mm strips of thin plasticard -- in an attempt to get six with vaguely the same spacing I made a little jig to space the tubes 7mm apart. Another jig was made to assist in gluing the results onto the ends of the skip at a standard height -- about 9mm above the bottom.
Jig to get the pivots spaced semi-accurately:
Jig to get the pivots fixed to the bodies at a standard height:
The skip bodies now tipped as required, but the mechanics of the movement around the pivot now reared their head. In the prototype, when the body tips from the horizontal to the vertical, the pivot on that side rotates a quarter of a turn, so the point of contact when the body is horizontal must be a quarter of the circumference of the pivot from the stop. In the model case, with a 3mm diameter tube pivot, this should be about 2.3mm, but I had allowed rather less than that, so the pivot rubs against the end stop -- not a problem, given the lightness of the model and its low friction, compared with the prototype.
However, when the body returns to the horizontal the pivot rolls the full 2.3mm, and that puts the body off-centre on the mount -- indeed, if I had allowed a bit less distance it would put the opposite pivot outside the end stop. In order to keep the body centered when returning to the horizontal I therefore glued two Cambrian Models rivets (which are quite large) to the mounts inside the two pivots -- when the pivot rolls back to the horizontal it reaches the rivet and goes no further, rotating against it until the body reaches the horizontal. Sounds complicated, works a treat, and isn't very noticeable.
Skip frames with body horizontal and tipped to the vertical. The locating rivets can be seen when the body is tipped:
The other fitting I put on the skip bodies was a pair of brackets at one end to hold a tipping arm -- when I get round to building the layout these are supposed to run on I want to have automatic tipping by a sloping bar at the side of the track, and automatic return to the horizontal by a wire overhead, and the arm can be fitted to tip on either side. As I will have to adjust the length of the arm by experiment, this method of fixing allows different length arms to be tried.
To make the skip frames look as if they are fixed together by something other prototypical than Plastic Weld I glued tiny slices of 1mm hex plastic rod in strategic places -- what seemed like hundreds of them, although the maths indicates that it was only about 120. I also substituted 10.5mm disc wheelsets (Bemo, I think) for the 12mm Hornby ones I bought to replace Helmut's, so that the frames now sit at the same height as Sidelines underframes.
All in all, the resultant skips look quite reasonable, and a bit different from what I started out with. Was all the work worth it? I suppose I could have had something very similar by buying the Slaters skips, and the cost would have been much the same -- ah, but the sense of achievement! Now what will Helmut think when I show him what I've done to his beautiful frames?
Now all I have to do is paint them -- you know my methods, Watson.