Buffer beams
Entry posted by Kenton
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Continuing with the footplate the next addition is the buffer beams.
These are made up of several layers laminated together. The front buffer beam is made up of five layers [8a-e] while the rear buffer beam is made up of 4 layers [9a-d]. the reasoning for the front buffer beam being thicker is so that more weight is added to the front of the loco. A lump of lead might have been easier and more effective? 
Do not remove any of the parts from the fret just yet as there are half-etched rivets to be punched out on the inner layers [8a,9d] for the reverse of the jacking brackets and on the outer layers [8e,9a] for the frame rivets.
There are half-etched dimples on [8b] but I don't see why as this will become a hidden inner layer, so these were not punched.
Time to get out the big boy's toy 
This rivet punch from G W Models is a wonderful tool to add to the bench. It comes with punch and anvils for 2mm, 4mm and 7mm rivets and can handle half-etched dimples or plain brass. With a table calibrated to 0.05mm in each direction it takes a bit of aligning - but once there you get great rivets. Beats a hammer and pin any day for consistent rivets.
It is always easier to perform this job while the parts are still on the fret as it makes the part easier to hold on the table. So while here I also punched the other parts on this fret [49.54,55].
Remove the parts from the fret and tidy up the edges. Remember the parts are not interchangeable and the front and rear parts should be kept separate from each other.
The outer layer does not have the handrail holes so building up the buffer beam sandwich is a two step process. Make certain that the beams are constructed correctly with the inner layer facing the correct way. When viewed from facing the outside of each buffer beam the hole for the brake stanchion should be to the right of the hole for the coupling (therefore the left when viewed from inside the frames). While holding the parts in alignment the inner four (three for trailing buffer beam) were soldered together. A small word of caution - take care not to fill the lamp bracket channels on the front buffer beam with solder.
Now fit the grab handles formed from 0.4mm brass wire to the front buffer beam only. Then clean up the inside face removing any wire protruding.
I am using the recommended Gibson buffers so the next step is to carefully empty the contents of the packet into a small component tray, after all there are springs involved. Then replace the springs and the buffers back into the packet, seal it and put it somewhere safe - they will not be needed for a long time.
If you examine the buffer holes on the beams you will see that the inner holes are larger than those on the outer layers. This has obviously been designed so that the bush that aligns and backs the buffer casing can still sit flush when the outer layer is added to the sandwich. So these bushes were soldered into the backs of the beam outer layers and the buffer casing soldered to the front - taking care that it was square.
Now the outer layer was aligned to the inner sandwich and soldered together. The edges were filed clean and square all round.
With the footplate bolted to the frames (it helps to keep them vertical), the buffer beams were tack soldered at the corners in position on the footplate. Care being taken not to solder them to the frames.
The frames were then unbolted and the joins were finished.
Well, that just seemed to take much longer than I was expecting - my eyes need a rest.
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