Bachmann Class 66: Subframes

This section describes the construction of the bogie subframes.

Annotated view of bogie subframe

Subframe mainframes On the Mainframe etches (S2), check that the slots in the sides are clear to take the etch thickness.

Make the two main longitudinal folds, each of which is in three parts carried over the transom sections under each axle slot. Ensure the folds are at a true right angle.

Subframe Seat-Ear etches Remove the spring Seat-Ear etches (S5) from the fret. There are two of each hand for each bogie.

Check that the small etched holes are clear to pass a 0.5mm drill.

Four tags folded Fold over the small tags at each of the corners of each Seat-Ear etch.

180 Seat/Ear fold Make the 180° fold, with the fold slot to the outside of the fold, at the centre of each Seat-Ear, to fold the two layers of the ear back on themselves.

Lateral ear Fold out the lateral restraint ear,…

Longitudinal ear … and the longitudinal restraint, from each Seat-Ear.

Seat/Ear Fold up Completed Seat/Ear fold-up.

Fitting Seat/Ear to Mainframe From inside the Mainframe, fit each Seat-Ear through the slots in the side of the Mainframe between the axle slots.

Soldering Seat-Ears Apply flux to the three laminations - etched holes are provided to facilitate this - and support them firmly together before soldering them in. Ensure that the slots and holes for the springs remain free of solder: use a 0.5mm drill to clear them if required.

Ensure each of the fold over tags along the top edges of the Seat-Ears is reinforced with a small fillet of solder.

Re-check that the main mainframe folds are at 90°, and then check against a flat surface that the eight secondary suspension seats are square and level.

Baseplate etches Remove the Baseplate (S1) etches from the fret and make the 90° fold at each end of each one.

Fitting baseplates Fit the Baseplates to the underside of the Mainframes (there are two different types, each of which will fit only the correct aperture) and solder in place.

Outer Stretcher etches Remove the Outer (S7)…

Inner Stretcher etches …and Inner (S6) Stretchers from the etch and make the two folds in each.

Some of the photos show an earlier version of the Inner Stretchers, without the two vertical slots.

The frames are not reversible. The 'two-spot axle' end of each frame is the outer, i.e. coupling, end.

Fitting Stretchers Engage the top parts of the stretchers in their slots in the Mainframe sides, support their lower ends against the Mainframe cross members, and solder them in place.

Finished Subframe, above Check that the whole assembly is square and true.

Reinforce each of the Mainframe folds with a fillet of solder. Take care to ensure that the region immediately around the axle bearing slots, for at least about 1mm around the edges of the slots, is kept free of solder.

Finished Subframe, below Clean off flux residues and tidy up excess solder from the outer surfaces.