BS006. Post-1936 'middle period' NZR couplers
These couplers are dimensionally accurate, scale representations of the real
thing, and conform to the proposed standard published in the April 1999
NZMRJ
. They should perform satisfactorily with any other coupler to this standard.
The coupler is designed to fit a small headstock opening. Sufficient sideplay
is obtained because the mounting is close to the rear face of the headstock.
Instructions
Separate the couplers from the sprue with a piercing saw. Clean them up with
appropriate abrasives and open out all holes to 0.7mm.
The hooks should be fastened in the hole furthest from the coupler face using a
0.7mm diameter pin. I form a head on a piece of brass wire by holding it in
the drill chuck and forcing it against a steel surface with the drill running.
I then file a notch where the prototypical hinge in the pin would be. Fit
everything together and make a bend at the notch to retain. Check that the
hook moves freely, and if not, relieve the hole in the hook until it does. A
pin also needs to be fitted in the hole nearest the face of the couplers
without hooks.
To achieve centreing, solder a 0.008" guitar string tail to the coupler
boss and retain this loosely on the wagon centre line about 50mm or so from the
headstock. The shorter the distance between coupler and retainer, the stronger
the centering force will be.
Mount the coupler so that the centre line is 11.5mm from rail height, and the
buffer face is 6mm from the headstock.
I suggest finishing the couplers with gun blue (Birchwood Casey Perma-Blue -
from a gun shop). The instructions say it won't work on non-ferrous metal, but
it does - for our purposes anyway. Just dip the coupler in for a second or two
and then wash in water or wipe dry. If it isn't dark enough, repeat. Easy,
cheap, quick and very effective! The resulting colour isn't quite right, but
you'll have a dark, robust coating as a base for further cosmetic colouring.