Type 4 couplings

I wanted to design some easy to make 006 couplings for fitting to locos and larger wagons, styled rather like my type 2 couplings but made from square styrene section for convenience. I chose to use 3mm material, and prepared a sketch on the back of an envelope (literally);

As I use link and pin couplings for 006 work there's a .4mm hole drilled for either a pin or split pin. The front face is filed to a curve.

The advantage of these is threefold, they're quick and easy to make, I can hold the material in a self-centring 4 jaw chuck, and, I can drill the pin hole by hand rather than set the machine up. 

Here's a batch that I've made (there were 6 but 1 didn't cut the mustard);

Note the front two coupled together. And that white plastic is a pig to photograph.

As these are 3mm square and I'm using a coupling height of 6mm a centre line needs marking on the bufferbeam of any vehicle they're fitted to, using a 4.5mm gauge that I made to use with my earlier couplings;

Once the height is marked a 1mm hole can be drilled and the coupling temporarily fitted;

The photo shows a 'link' coupling.

Like all of my 006 work these are an experiment, so I need to fit them to a pair of waggons to see how well they work.

Paul.

Type 3 couplings

This style of coupling is based loosely on the type fitted to many Hudson Hunslet diesels, albeit simplified by making it with a single slot rather than two.

I started with my usual rough sketch, which after making a couple of prototypes ended up being re-drawn in something-angle projection;

(With no apologies to any engineers, real or model, who've stumbled upon this page - I make things rather than worry about proper method.)

With the Unimat 3 set up as a mill and a piece of 6mm dia. brass set up in a dividing head the basic shape can be milled;

To mill the slot I use a .5mm slot drill with the work held in a collet chuck clamped to the saddle;

A .4mm hole, for the coupling pin, is then drilled, but left blind;

The last machining operation is to turn a 1mm dia. locating spigot on the rear and then part-off;

Before each part is parted-off the buffer face needs to be filed to a gentle curve. Here's the almost-finished result;

Now they can be fitted with a pin, .4mm brass wire cyano'd in place with 2mm left protruding.

After much deliberation I've decided to use a coupling height of 6mm for my 006 stock. To set the height for these couplings I first turned a 4.75mm height gauge to mark the centre of the coupling (coupling height minus half the coupling, 1.25mm);

Once a 1mm hole is drilled on the centreline the coupling can be tried in place;

And checked with a second gauge, turned to 6mm;

The finished coupling is a result of quite a lot of work, but to my mind the right coupling can make a loco.

These are destined for 006, for 009 the coupling needs to be lengthened to 3mm.

Paul.

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.

OO9 couplings - type 1.

Recently I decided that making my own loco buffer/couplings might be a nice little project, and a good way of personalising a model. So as a start I've machined up some couplings for my Saltford Models Audley. I have a few different coupler variations in mind, so I'm calling these my type 1 for future reference. (The main reason behind this blog is to record my work for my own use.)

The first job was to make a fag packet sketch (quite difficult when you don't smoke!), then from that a prototype which I wasn't overly happy with. So after a quick revision I set to work.

The first job was to mount a length of 6mm bar in a machine vice on my Unimat SL and drill a .6mm cross hole about 2mm from one end;

To position the drill in the middle of the bar I made a mark on one side with a permament marker pen. Then the drill was lowered and moved across until it just touched the bar and left a witness mark (which can be seen in the photo above). Then with the drill raised up again the vice was moved over by half the diameter of the bar plus half the diameter of the drill (3mm + .3mm = 3.3mm). This positioned the drill exactly on the centreline of the bar, and a hole could then be drilled through.

Now the bar could be transferred to my Unimat 3 and the basic shape turned;

The head is 5mm dia. x .9mm long, the shaft dia. 2mm dia. x 2.2mm long and the coller 3mm dia. x .6mm long. There's also a 2mm dia. stub to fit into a hole drilled in the loco's bufferbeam. I carefully machined the shaft with a grooving tool making sure that the .6mm hole sits directly behind the head, machining the head to length after all the basic turning is done. Finally the head is rounded off with a file and emery paper,

At this stage its not unlike a normal buffer.

Back onto the SL next, set up in the vice with the .6mm hole set vertical, done by placing a drill into the hole and checking with a square. Then 1mm is milled from the top of the head,

The final machining operation was to part the coupling off in the U3. Then the end of a length of .6mm brass wire could be tinned and soldered into the hole, being trimmed to length afterwards with 2mm sticking up;

I machined up 3, just in case I made a mistake!

Now, normal OO9 coupling height is set at 6mm above rail level. The centreline of these sits at 4.5mm above the rail top, so I machined up a 4.5mm thick gauge so that I could mark the bufferbeam for drilling;

Here's one coupling in place, after drilling a 2mm hole in the bufferbeam;

It suits the loco, sits at exactly the right height and should work rather well. Quite a satisfying little job.

Remember that clicking on a photo brings up a larger image.

Paul.