009 couplings - type 2.

Having previously decided that machining my own 009 couplings, at least for locos, is a good way of personalizing a model, as well as being an interesting diversion and a good machining practice, I decided to make some more to a different design.

The first step was, as always, to knock up a back-of-an-envelope sketch, then from that machine up a prototype. This helps me in a couple of ways, I can see how the finished part will look and make any changes that I deem necessary, and work out the best way to machine the final design.

Once I was happy then I could make a new, better drawing. 

Of course the size and shape of the coupler 'head' (the business end), the base (where it is joined onto the bufferbeam), and the shank (the part that locates in the bufferbeam) can be altered to suit, the lengths however shall remain constant. For these couplings I made the head 6x3mm, the base 3x3mm, and the shank 1mm dia x .4mm long (to suit a brass loco. For a whitemetal or plastic bufferbeam I might make the shank longer and/or larger).

The first job was to turn the basic shape;

As the base and head are square and rectangular respectively I had to work out the distance between the corners, then turn down to suit but leaving on an extra .1mm;

Now a .45mm hole could be drilled just behind the head (for the coupling pin);

Note the pin chuck being held in a collet.
Then, with the .45mm hole set square, the flats were milled, using a dividing head;

Each coupling could then be parted off;

Next, the working surface of the head was filed to shape, an Eclipse vice being used to hold the parts. The final operation was to broach out the .45mm holes to accept .5mm brass wire, which was soldered in place;

As the centre line of these couplings is 1.5mm below the operating height I used a simple gauge that I made previously to scribe a centre line on the loco's bufferbeam;

A hole could then be drilled in the bufferbeam to accept the coupling's shank, and the couplings soldered in place;

Paul.