Bachmann 'Peak': Bolster

This section describes the assembly of the Bogie Bolsters, taking one at a time.

Peak Bolster annotated

Pivot components Collect together one each of the supplied 12BA screws and nuts, one of the smaller brass top-hat bearings, and one of the smaller etched tag washers (P5) from the fret.

pivot assembled Remove one of the Bolster Frame etches (B2) from the etch.

Check that the slots in the etch are clear to pass the material thickness.

Place the washer and top-hat bearing (flange towards the washer) on to the 12BA screw. Apply a smear of grease to the lower face of the bearing and to the projecting screw threads. Pass the screw through the pivot hole from the plain side of the etch, thread on the nut and tighten the assembly.

pivot nut soldered Apply a generous fillet of solder around the sides of the nut, keeping the etched fold lines clear.

Trim the pivot screw to length so that it projects no more than about 1mm below the nut. Keep the screw in place to secure the nut during subsequent soldering.

Folding Bolster Frame Make the two folds in the Bolster Frame etch.

Inserting Frame into Base Remove a Bolster Base etch (B1) from the fret.

Check that the slots in the etch are clear to pass the material thickness.

Fit the Bolster Frame into the Bolster Base. Start by fitting the cross-member of the Frame through the widest part of the aperture in the Base…

Springing legs of Frame into Base …then spring the outer and inner legs of the Frame into the aperture, and manoeuvre the Frame into position.

Frame in position in Base Push out the sides of the Frame to reset the folds to as close to 90° as you can get them.

Locate the tags at the inner and outer projections of the Frame firmly into their slots in the underside of the Base and solder them up. Keep solder away from the other parts of the frame for now.

Inner Leg etch Remove one of the Inner Leg etches (B3) from the etch.

Check that the slots in the top edge of the etch will pass the material thickness.

Inner Leg sideframe support, first folds Make the first fold in each sideframe support foldover, and reinforce the folds with solder.

Inner Leg sideframe support, second folds Make the second folds in the sideframe support foldovers. Check that the foldovers are parallel with the rest of the etch, and reinforce the second folds with solder.

Inner Leg, top stiffener bracket Fold up the small stiffener bracket at the top of each leg.

Inner Leg, leg back folds Fold in the outside of each leg.

Inner Leg, top plate folds Fold down the top plate of each leg.

Inner Leg: sideframe support foldbacks Fold back the sideframe supports onto the outer face of each leg. These folds are made at 180°, with the etched folding tags on the insides of the folds.

Check that the foldbacks are aligned parallel with the edges of the legs, adjusting the folds if necessary.

Apply flux to the joint between the foldovers and the outer faces of the legs, crimp the 180° folds firmly closed and solder them up.

Completed Inner Leg foldup The completed Inner Leg foldup. The lower cross piece is a spacing and alignment jig which will be removed later.

Outer Leg etch Remove one of the Outer Leg etches (B4) from the fret.

Pay attention to removing the tag in the centre of the lower edge of the cross member, so that the edge is straight and true.

Outer Leg, sideframe support, outer fold Make the outer fold in each sideframe support, and reinforce the folds with solder.

Outer Leg, sideframe support, inner fold Make the inner fold in each sideframe support and reinforce the folds with solder.

Folding bracket Fold in the small support brackets at the tops of the legs. Support them well to prevent them from distorting.

Outer Leg, folding leg sides Fold in the side of each leg. Again support the folds well to avoid distortion.

Folds at top of Outer Leg Fold up the ends of each secondary spring retaining tab. Support the etch to prevent it bending where it narrows around the hole.

Make the inner fold in each secondary spring retainer.

Fold in the stiffener plates at the top of each leg.

Folding back outrigger Fold back each sideframe support outrigger against the outer face of its leg. These are 180° folds with the half etched folding tag to the inside of the fold.

Check that the foldbacks are aligned parallel with the edges of the legs, adjusting the folds if necessary.

Soldering Outer Leg outrigger Apply flux to the joint between the foldovers and the outer faces of the legs, crimp the 180° folds firmly closed and solder them up.

Inner Leg foldup in Bolster Support the Bolster assembly inverted between two flat, heatproof blocks. Fit the Inner Leg foldup into position on the Bolster assembly.

Soldering Inner Legs Apply flux to the mating surfaces between the Inner Leg etch and the existing assembly, to the folds of the legs themselves, and to the joints between the Frame and Base up to the gap in the middle of the bolster.

Hold the Inner Leg etch firmly in place, correctly aligned and with joints pushed fully home, and hold closed the joints between Frame and Base. Apply a generous amount of solder to the top of each leg, allowing the solder blob to conduct heat into the joint, lingering with the iron until the solder is sucked in to the joint and flashes around the folds.

Keep solder away from the inward facing surfaces of the legs, as these slide against the lateral control ears of the Subframe.

Outer Legs fitted Fit the Outer Leg to the Bolster assembly, ensuring that the small tabs and slots are engaged. The cross member is a jig piece for distance and alignment, and will be removed later.

Soldering Outer Legs Apply flux to the mating surfaces between the Outer Leg etch and the existing assembly, to the folds of the legs themselves, and to the remaining unsoldered joints between the Frame and Base.

Hold the Outer Leg etch firmly in place, correctly aligned and with joints pushed fully home, and hold closed the joints between Frame and Base. Solder up the Outer Legs and Frame.

Turn the Bolster assembly the right way up and check that it sits truly on a flat surface, with the legs vertical and joining tabs tightly home in their slots. You can re-melt the joints and adjust them if necessary.

Cutting away jig pieces Cut away the transverse jig pieces between the Inner and Outer Legs. Put them to one side as they are used later when fitting the Pivot Frames to the loco.

Bolster Legs finished Tidy up any remnants of the jig pieces using a file.

Pair up the bolster with its subframe, as designated by the presence or absence of the etched triangular marks on the Bolster Frame and the Subframe Mainframe. Orientate the Bolster and Subframe correctly - the 'pointy' end of the Bolster faces towards the outer end of the Subframe.

Check the fit of the Bolster on to the Subframe:

A tight fit can be addressed by light filing on the radiused edges: they have been drawn to be slightly over-size with half-etched guide marks to help preserve the correct shape.

That completes the brasswork for the bogie bolster.