This is my version of the Plus Four Wristlet Route Indicator which was a device from 1927 worn on the wrist like a watch that had a small paper scroll of printed driving directions in it.
The driver would turn the little knobs to scroll through a little list of directions to their destination. In car navigation before GPS!
It occurred to me (and others going by the comments in the link above) that you can easily make a list of directions like that using Google maps. So I gave that a try. I selected a route and plugged it into Google maps and produced a list. A little editing in something like Openoffice and you can print out a nice shopping list of directions. All I needed was something to use them in.
I went out to my shed and rummaged in my box of brass bits and pieces and threw this together.
The body is all hand soldered from brass modeling tube. There are two cylinders, each with a slot cut along one edge. They are soldered to a flat back plate that the strap is threaded though. The ends are made from more small pieces of brass. On the front are some flat pieces and rods that the glass window press up against. The window is made from a glass microscope slide I cut down and glued in place with some windscreen sealant. The strap was just a scrap of green leather I had with a buckle attached to one end. I made the strap large so the watch can be worn over your sleeves so you can see it when driving.
The far end of the cylinders are plugged with small turned pieces I machined up on my mini lathe. The scrolls are made from long 1/8 inch brass machine screws. The ends were machined on the lathe and they are a nice, smooth fit into the cylinders. They are soldered onto the screw leaving a about 1/8 inch of thread on the far end for the knobs to be screwed onto.
The knobs on the end were made from acorn nuts and a piece from a binding post screw. Those are used to bind loose pages together into a booklet. I drilled out the centre of the binding post screw and pushed that down over the top of the acorn nut and soldered it in place. This gave me a little knurled knob with a domed end that can be screwed onto the end of the scrolls.
The directions are printed out onto a 35mm wide strip of paper and then simple taped and wound onto the scrolls. The scrolls need to be would into an ‘S’ shape. This is so that you can advance the list by turning the top knob clockwise and you reverse the list by turning the bottom knob clockwise also. This is very important! Because the knobs both use a standard thread you turn them clockwise to tighten them. If you turn them anti-clockwise the knobs unscrew! There is enough friction in the scroll and paper that turning the knobs backwards will cause them to unscrew.
To load the device you unscrew the knobs and insert the scroll into the watch ensuring the paper slides nicely through the slot in the left hand end. The threaded ends of the scrolls will poke out the right hand side of the watch. You then screw on the knobs which then prevent the scrolls from sliding back out.
The glass window, an improvement on the original device as far as I can tell, stops the paper getting wet in the rain when you are driving your convertible sports car with the top down.
The amazing thing is it actually bloody works! You can easily fit the length of an A4 sheet of paper into it which will provide around 25 different directions when printed at the size shown. Of course you could simply shrink the size of the text and fit many more.
Here are more pictures of it in action. Oh and the beauty of this device – it is silent!
Update: 22 August 2010
Just a quick note for all those interested in this. It isn’t Steampunk! At least I don’t call it that. It’s just made of brass. Also the car is an MGB.