Decided the thick plate was too thick for the main footplate at 1.2 mm and found some ,5mm brass instead. which is flat plate as well, and can take a strip of the .5 mm in a groove along each edge cut on the milling machine, This acts as the side strip valence, complete with the profile at the front, but the steps at back will be soldered on.as a solid piece with steps would be wasteful of material.
The ends have 5x5 angle brass soldered on to take the buffer beam bolted on, This is confined to within the frames width so that frames use the angle strip as location.
Both the sides and the buffer beam have been drilled for rivets using brass pins. The head is reduced with a fine needle file, fixed to a jig so that the pin rests on the wood as it is rotated by a Dremel type drill The wood rest guide forces the same diameter on each one, then the head is rounded with finr emery paper glued on to a board.
On soldering the side valence on, the pins are fitted with solder paste and heated in one go to secure them, same for the buffer beam. Cupalloys do proper solder paste. All Soldering is done with Bakers fluid flux, with pure tin solder and 60/40 lead solder plus lower melt solder for details
Once solid with the valence and buffer beams the space over the frames under the boiler can be cut out by fretsaw or more likely on the milling machine.
The opening is just narrower than the frame inside back to back, but goes full width at the firebox end, and stops at the backhead position. This gives clearance for the cladded firebox. but leaves an over hanging edge around the motion area.
No cut out is used under the smoke box, which has a brass plate bottom, drilled and tapped to be screwed down to the footplate.
Next is the front plate of the cab, again fitted with brass angle on each side to bolt down.
The centre line of the boiler is determined by the back of the smokebox and checking on the drawing, and then the front cab plate can be marked and a disk fitting the tube bolted on.
The boiler can be adjusted level at this stage, and the disk soldered up solid.
The area of the tube in the firebox can be half cut away. to get motor space.. An end plate is added.to the boiler with tapped holes to assemble it into place.
The front just rests on the smokebox ring disk, no need to secure really, although a bolt into the smokebox back could be used, accessed via the smokebox door.
By now the main structure is complete and the sides of the cab. with soldered on front and top can be added. and a box made in brass for the coal area, again bolted into place on the footplate.
The backhead can be cut out to shape and bolted to the cab front plate. The roof can be attached with an angle iron strip to locate it and be bolted on with screws from inside, filed flush outside later in finishing.
By now the body is approaching completion. and the work moves back to the chassis.
The profile is cut out and frame spacers marked in and axle positions drilled, using the frames as jigs to mark out the rough connecting rods..
In this case the inner frames are drilled with the other parts. but then the outer frame holes are re-drilled 2mm larger to allow the inner chassis to pivot. Once the inner chassis is on its frame spacers and checked true, it is attached to the outer frames with clamps, and held in line by dummy axles, the pivot points is drilled each side, tapped in the outer frames, the inner opened up to take a shouldered screw.
The inner chassis is removed and fitted with bearings, and then assembled ready to have the wheelsets added, in this case pushed on.
Once quartered the rough rods can be added and running checked for binds.
One of the frame spacers on the main chassis should align with the bogie pivot and allow a post to be fitted to take the bogie bolster. The bolster hole in the bogie should be a slot to allow a bit of side movement, with a phosphor bronze spring to centre it on straight track. The whole frame spacer should be made from Tufnol to insulate the bogie from the chassis and body. washers cab be used to level up the chassis, fitted on the post. A nut and light coil spring retains the whole bogie. allowing a little rocking play under pressure.
Next is adding the motor on a frame attached to the inner frame, and connecting to the gears.
At this point the body and chassis should run, and then it is taken apart to add all the detailing.
An important point is the inner chassis must clear the mainframes by about .25mm to allow painting. on assembly, with washers being added which prevent the paint rubbing.
All the rest is a lot of detailing all round from boxes to hand rails, coal rails, whistle and backhead detail, plus any edging and polished brass parts like dome and safety valves
The brake gear should be attached to the sub chassis and move with the wheels as it pivots.
Buffers will be sprung, made in stainless steel.The bogie will be all brass and nickel, with milled axleboxes, and turned leaf springs made in a ring and sawn up. Stainless steel disc wheels will be fitted on 3mm axles with outer 2mm stubs to fit the ballraces on. Insulation by tufnol centres on one side.
Plain DC 12 volt operation, no chips or complex DCC here.
About a months work, but health problems might slow it down a bit. At least underway, with wheels to be ordered on Monday.
Posting as work proceeds with photos.