EE 6-wheel Bogie; Brake Detail

These instructions deal with fitting of the brake gear components supplied on fret F011. We recommend fitting the brake details at this stage, because the details are fixed to the subframe's traction outriggers and there is, therefore, some interaction between adjustments made to the outriggers, to fit the bolster, and the relationship of the brake shoes to the wheelsets.

The fret has been designed to assist in drilling and folding operations. We advise that you do not remove components from the fret until indicated in these instructions. In many cases, small components are folded 180° on to larger ones on tags which assist with alignment. With the fret supported on a firm, flat surface, you can make these folds with two small, flat-bladed screwdrivers, or similar implements, one pressed on to the tag to define the position of the fold and one acting on the smaller component to drive the fold over.

central details With a 0.35mm drill in a hand pin-vice, check that the drill will pass through all the fully etched round holes in each component, drilling them through gently if required. To help prevent distortion, hold the parts against a hard, flat surface while drilling.

There is fine detail in the etch which can easily become obscured by solder. It is perhaps as well to tin all components with a thin film of solder now, to avoid bringing excess solder on the iron to the components when assembling. Run through the holes with the drill again after tinning.

central brake detail Taking the central brake details (items 5, 6, 7, 8 on the Component Map), fold over (180°) the shoe detail laminations. Pass a short length of 0.31mm wire through the hole in the shoes for the centre wheelset, and solder the laminations together. Trim the wire flush with the back of the shoe detail, but leave a short stub protruding from the front to represent the end of the cross rod.

A useful jig is a piece of tufnol with a 0.35mm hole drilled close to one edge. The component can be rested on the edge of the tufnol, with the face of the brake shoe over the edge, and the wire passed through in to the hole. Solder may then be applied to the face of the shoe and allowed to flash through the joint, at the same time infilling the laminations at the front face of the shoe, whose surface may then be finished with a half-round file.

Orientation terminology This image shows the terminology we have used below to identify the brake gear parts, and which lower boss shapes go where when you come to fit the central details. Note that the bogie subframe is inverted in the image. See also the Component Map included in the F011 pack.

Folding bosses Taking each central brake detail etch in turn, fold up (180°) the bosses at the lower ends of each brake hanger (hold the fret against your hard, flat surface with the flush face of the half-etched fold tags facing outwards).

central detail Align the bosses with the blind end of a 0.35mm drill, and remove the component from the fret. Solder a short length of 0.31mm wire into the bosses of the hangers facing the outer and inner axles (i.e. those whose shoes do not have the wire cross rod end detail) and trim it to protrude about 1mm or so from either side of the detail. The tufnol jig is useful again for this. Secure the other bosses with a touch of solder; there is no need to fit 0.31mm wire to them (although we did do so in the photo here), unless you intend to fit the centre axle's pull rods (see following note).

There are 20 pull rods on the etch, enough to fit inside and outside rods around the inner and outer wheelsets of each bogie, and to fit outside rods to the centre wheelset. To allow sideplay, on a working model, we suggest that the centre pull rods be omitted altogether, as they are virtually invisible in service. There is a fold-over boss spacer at the end of each rod, to provide ample clearance between rods and wheels on the inner and outer axles of a working model. For a finer appearance, you might wish to experiment with omitting the spacers.

Check, with a piece of scrap etch, that the slot, at the back of the shoe facing the inner or outer axles, which forms a halving joint with the subframe outrigger, is clear to the material thickness. If required, open it up with a 0.4mm or 0.45mm drill, used as a file.

Remove and clean up the half-etched fold tags at the bottom of each brake shoe. It's probably as well to leave the upper tags in place, as they're invisible when fitted and help prevent the detail from coming apart during subsequent soldering. They might, later on, need a little nip with a file to avoid interference with vertical movement of the wheels.

outer fold Make the outer folds in the central brake detail. Apply flux carefully to this fold only, and touch the iron against an outside corner of the fold to allow solder to flash into the fold and reinforce it, without filling the half-etched lines for the adjacent folds.

inner fold Make the inner folds. The outer folds should not distort as they have already been soldered. Reinforce the inner folds in a similar manner.

Taking one of the bogie subframe assemblies, assign each of the four central brake detail etches to its correct position on the subframe (see above). Locate the detail etches in the slots in the top of each of the subframe's outriggers. Each slot makes a halving joint with the similar slot in each brake detail etch.

Assembling central details to subframe Support the detail etches in the correct alignment and solder up the joints, taking care not to let excess solder flow into the detail. It is convenient to invert the assembly and support the detail etches on two parallel blocks, as shown. Check that the etches are parallel with the subframe both horizontally and vertically, reheating and realigning if necessary.

Test fit wheelsets Test fit the wheelsets to check that there is sufficient clearance between the brake shoes and the wheels over the operating range of the suspension (the design static position of the wheelsets is with the tops of the bearing carrier ears level with the top of the subframe sides, with dynamic deflections of ±0.5mm service, ±0.75mm max, from there).

The brake gear is designed to give a minimum clearance between wheel (15mm diameter) and shoe of 0.5mm. With natural variation in assembly, clearances can be tight, especially with a full 15mm wheel. We suggest tweaking, if necessary, of the detail etches and subframe outriggers to get clearance for the shoes against the centre wheelset, then, if required, filing of the shoes facing the inner and outer wheelsets (they're invisible once the bogie is fully assembled).

check bolster fit Any adjustments to the outriggers will, in turn, affect the fit of the bolster between them, so check that fit and either make any adjustments required to the bolster, or look again at your initial tweak to the outriggers and/or brake detail. Also check that the brake detail etches do not foul any parts of the bolster secondary spring detail over its normal range of movement relative to the subframe.

End shoe guide detail If you have not already done so, make the two joggle bends in the brake shoe guides at the ends of the subframe stretchers as shown. Try to avoid any 'stretcher outrigger droop', as exhibited to the left of the photo! Test fit the wheelsets to ensure clearance between the inside faces of the shoe guides and the outside faces of the wheels.

Now we turn to the end brake shoes and their hangers, parts 1, 2, 3, 4 on the Component Map. Each shoe and hanger assembly is made up of an inside and outside lamination. Note that, for more efficient use of fret space, the inside laminations (1, 2) are etched adjacent to the outside laminations (3, 4) of the opposing pair.

fold over shoe detail Fold over the shoe detail (180°) of the outside laminations (3, 4). Align the folds using the blind end of the 0.35mm drill through the holes in the shoe.

end shoe upper bracket Cut through the tag holding the top bracket detail, as close to the detail as you can, and fold over (180°) the bracket, aligning through the upper pivot holes with the 0.35mm drill.

end shoe, lower boss folds Fold over the lower boss detail (180°), this time folding the larger part of the component over on to the small boss, as far as you can with the component still on the fret. Then cut the remaining tag, as close as you can to the boss, and complete the fold, again making the final alignment with the 0.35mm drill.

Similarly fold over the top brackets and lower bosses of the inside laminations (1, 2), ending with them removed from the fret.

end shoes Take a pair of inside and outside laminations (1, 3 or 2, 4) and apply flux to their shoe and lower boss areas. Thread the pair together on a length of 0.31mm wire passed through the holes in their lower bosses.

end shoes, second wire Thread a second length of wire through the holes at the other end of the hangers.

soldering end hangers Insert the first wire into the hole in the Tufnol jig, with the inside lamination face down against the jig. Press the laminations together and solder up the assembly. While the solder is still molten, withdraw the second wire. You should find that, when it cools, the solder forms a small dimple at the location of the hole, which can then be redrilled 0.35mm. Trim the free end of the first wire to about 1mm.

A better alternative, which we haven't yet used successfully, might be to use a length of 0.3mm pencil lead rather than the second wire (a trick borrowed from Mike Clark). Check the exact diameter of the pencil leads before starting and drill holes accordingly before removing parts from the fret (our 0.3mm leads turned out to be 0.4mm diameter).

drilling centre of end shoe Drill the hole in the centre of the brake shoe detail 0.55mm, to allow the 0.5mm brass wire supplied in the kit to be inserted freely.

Clamp the component in a vice, and gently finish the edges of the shoe and hanger with files to reduce the laminated appearance. Remove the folding tags from the top and bottom of the shoe. Keep the folding tags on the lower bosses and upper brackets, for now.

Repeat the above for the remaining seven pairs of laminations.

pull rod folds Returning to the fret F011, place the fret on a hard working surface such that the flush sides of the half-etched folding tags of the pull rod bosses are facing upwards. Apply a light smear of paste flux to the boss surfaces and fold the bosses (180°) over onto the rods, finally aligning the folds with the blind end of the 0.35mm drill.

Cut through the tags to separate the pull rods from the fret.

Rigging end brakes Cut two lengths of 0.31mm wire, each long enough to span between the outer end of the subframe stretchers and the vertical sides of the subframe. Take the end brake shoe/hanger for one side of the inner end of the bogie (the end without the guard irons) and, on that side, thread one of the wires through the hole in the stretcher end, then the top hole of the brake hanger, then the hole in the end of the vertical side of the subframe.

As you insert the wire from the outside, use small, flat-bladed screwdrivers to steer the wire through the holes.

Take one of the pull rods, orientate it with folding tags facing downwards and the end with the half-etched 'slot' detail towards the end of the bogie. Thread the pull rod on to the 0.31mm wires protruding from the lower bosses of the end brake hanger and of the central hanger facing the inner axle.

Aligning end brakes Align the end brake hanger with the slot etched in the upper flange of the subframe stretcher, and use the wheelset to check for clearance. If fitting 3'7" (~14 - 14.3mm) wheels, you might consider making a closer fit by opening up one of the half-etched holes in the pull rod, separating and repositioning the fold-over spacer, and fitting that hole over the wire at the central hanger. When satisfied with the fit (if a touch tight you can file away a little from the shoe, once fixed), solder the pull rod and end shoe detail in place.

end brake cross rod On the other side of the bogie, thread the brake shoe/hanger onto its wire as before. Align the end brake hanger with the slot etched in the upper flange of the subframe stretcher. Cut a piece of the 0.5mm wire exactly to length to span between the two brake shoes, protruding just slightly from the detail on each side.

Use a vernier to capture the dimension then cut the wire against that.

Thread the 0.5mm cross rod into place through the end brake shoes. Fit a pull rod to the unfixed side, choosing the correct hand and orientating as above. Solder the cross rod into the shoe on the side already fixed. Back to the unfixed side, align the brake shoe/hanger with its slot in the subframe stretcher, then solder the hanger and pull rod in place.

end brake cross rod Test clearances against the wheelset once more and, if necessary, file the shoe faces to fit.

fitting inside pull rod Fit the inside pull rods over the inside-facing ends of the 0.31mm wires. Solder the outer ends only…

clipping inside pull rods …then cut the rods just short of the axle centreline. Remove and discard the inner ends. Bend the remaining part of the rods to clear the inside faces of the wheelset.

outer end detail Repeat the above for the end brake detail at the outer end of the bogie. Here you have the additional factor that the 0.31mm wires, from which the end details hang, also must be threaded through the holes in the guard iron ribs. This path rarely turns out to be straight, but the wire is flexible enough to be guided/steered through and provides effective strengthening once soldered in.

Assembled brake gear To finish off, trim off the excess lengths of 0.31mm wire, leaving short stubs protruding to represent the ends of the securing pins. Dress the components with a file to remove the fold tags and to reduce their laminated appearance, though perhaps don't overdo it, as on the prototype the pull rods and hangers are also assembled as a laminated sandwich of components. You can also now dress the guard irons to remove the etching cusps from their edges and tidy them up.

That concludes the fitting of the brake gear details and, indeed, the assembly of the brass bogie components. If you wish to chemically blacken the bogies, this is a convenient stage to do so.