Each head is a circular billet of aluminium with a rectangular hole machined in the side. This part has been black anodised. There is a turned brass knob in the top of one of the clamps. Both heads are secured to their respective timbers with brass machine screws.
Like most items from Lee Valley Veritas the item is very well engineered and finished. They simply clamp two pieces of wood 3/4" wide x 1/4" thick against each other. The below photos are from pictures available on the internet (my camera is away for repair!)
In practice you make two 1/4" thick x 3/4" wide sections of wood whatever length you want. Cut a point on one end of each piece. Then slide the pieces into two of the clamp heads and tighten both screws. Each point should face away from each other. Then to use you simply loosen the screws and slide the wooden lengths so they fit inside what you are measuring. It is great for comparing across corners of a drawer, casework, cabinetry etc to square for squareness.
Also you drill an 1/8" diameter hole about 1" from the stub end of one and the pointed end of another. In the holes you simply screw some brass threaded pins (supplied) and you can cover all internal dimensions from about 1/2" to just slightly less than the length of the gauge.
So the gauge essentially has a capacity from 1/2" to the extended length of the bar. Very impressive and a very simple, effective solution.
|View showing clamp heads|
|Using the threaded pins|
|What is in the box|
I made mine from a few pieces of scrap beech and oak I had lying around in the shop. I made two sizes, 1 pair at 19" long. 1 pair at 30" long. This covers most of the case work I do. If I need longer, shorter or intermediate sizes it is really easy to rip another couple of lengths. I finished them with a little left over oil based finish I also had lying around the shop.
In the UK the clamp heads are available from Axminster and cost £8.46 + shipping.