More from the workshop

Carrying on from my last post, I thought it might interest readers to have a look at some of the other equipment that is used to create our models.
In the middle of the workshop is a George Alexander engraving machine. This was purchased nearly 25 years ago from a guy in Kent who had used it to die-sink the tools used to mould PECO's flexible track.  I use it in two ways: to cut out difficult shapes used in pattern making and as a copy milling machine in the production of small batches of models. A pattern is made of the required shape in Formica or plastic sheet. This is usually made twice as large as the finished object. The pantograph reduces this as you trace round the edge of your pattern.  A cutter head rotating at 12500 rpm holding a solid carbide cutter cuts the shape out. Because it is smaller by the ratio set, it is more accurate. These old machines are easily capable of achieving one or two thou accuracy.

The Alexander machine

The next machine is a Tom Senior Milling Machine, again, a lucky purchase since it was fully equipped for both horizontal and vertical milling plus it had the high speed vertical head shown in the picture. It had everything - rotary tables, boring heads, cutters, arbours ... The person who owned it had died in his workshop just after installing his new purchase. Once I had set it up, I nearly repeated the story. When I plugged it in, it immediately blew a fuse. Whoever had first installed it, had mis-wired the starter. Luckily, I wasn't touching it! I then rewired the whole thing with proper armoured cables and flexible conduiting. There is a cautionary lesson here. Anything that you buy, check. If you don't know how to, pay an electrician to check on your behalf. Senior Mills like this one were built with no expense spared. I have heard that the company lost money on every one that they made; consequently, they went to the wall.

Tom Senior Mill with vertical head

The last machine is a Britan repetition lathe. These were made by the hundred in the last war. They were used to produce items such rivets for the aircraft industry. They are copies (with many improvements) of a Boley (German) repetition lathe that had been in production since early last century. One interesting anecdote is the German lathe incorporated a waist belt with a hook on it that engaged with the lever that moves the cutting tool back and forth. It seems our German friends were quite happy to swing their hips to move their tools!

The Britan. The tool guard is on the high chair, the various operating handles can be seen and in the tray, above the number plate can be seen the thin operating lever of the hydraulic feed control

Britan added to the lathe a hydraulic system to move the cutting tools and the tailstocks if required and a pneumatic system to operate the bar feed. The Britan's method of using the cutting tools makes them simple to grind and extremely rigid in operation. It is a direct precursor of the modern CNC machining centre. We use it to manufacture all the steam fittings for our locomotives from gland nuts to regulators.

Britan again. The cutting tools are held in the rotating cassette. The stop tool against which the bar stock will come to rest is resting on the tool slide. It is this tool support that gives the machine its extreme accuracy and ensures the rigidity of the tool. On the right you can see the double tailstock which is simply swung over by releasing the catch. The upper tailstock is holding a Coventry diehead that threads - and the lower tailstock is holding a rotating cassette for drills etc.

If anyone is interested in more details, get in touch.