Counterweighted Parallel Arm Binocular Mount
Posted 09 June 2012 - 04:19 PM
One of the main features of the binocular mount is that the binoculars keep the same view when repositioning the height of the observer and can be used standing, sitting, or laying down. Shown here is the mount positioned for someone sitting or laying:
The binocular mount was made many years ago using only hand tools, 13" lathe, belt sander, and 14" bandsaw. This was a typical ATM project with materials used range from surplus cannibalized microscope mountings, linen filled phenolic composite, magnesium alloy, 3" diameter 6061-T6 aluminum tubing, assorted 6061-T6 aluminum flat pieces, a 1" diameter surplus aircraft control rod with tapered ends, cast iron body building weights, Thomas fluid filled camera head, and whatever was available that could be scrounged or bought surplus. Part of the process was to learn how to work with scrounged materials and at the time, to learn the skills of how to use my newly acquired 13" lathe.
The binocular mount was designed to be disassembled by one person for transport in a small car. This meant that the counter weight should separate from the main mount body, the mount body separate from the tripod and the tripod collapse into a transportable size. The tripod was covered in another post.
I decided on using 3" diameter 1/8" wall aluminum tubing I had on hand for the main structural component. This also meant that mounting counterweights on the thin walled tubing would have to be a bit different from mounting on a solid shaft. I solved that problem by making a double tapered sleeve that fit between two 8" diameter x 1" thick cast iron counterweights, turned from body builder's weights, and the 3" aluminum tubing. By cinching the two cast iron counterweights together using three 1/4-28 SHCS the counterweights can be adjusted and are firmly held on the thin walled 3" aluminum tubing without damage. Shown here is the counterweights on 3" 1/8" wall aluminum shaft:
Another issue was to have a threaded coupling so the counterweights and shaft could be removed for transport. I came up with the idea of using a male threads that were internal to the 3" tubing with smooth boss and female internal threads on the counterweight shaft. To prevent galling I turned the male threads inside of the 3" tubing from linen covered phenolic. Shown here are the female threads on the counterweight shaft and the male threaded boss inside the 3" tubing:
Note the flaking black coating on the counterweights and shaft. The shaft and counterweights were coated with a rubber coating, the kind one dips tool handles in. this turned out to be a mistake for over the years the rubber coating did not survive dings and bumps when being transported.
The next issue was the bearing for rotation around the tripod. This was accomplished by using the 3" aluminum as a shaft and phenolic material to bear against. Shown here is the tripod top with phenolic material used as a bearing surface:
The aluminum shaft that fits into the tripod is threaded at the bottom. A non-rotating aluminum ring fits onto a keyway cut into the 3"threaded shaft with aluminum nut are shown here:
The main body of the mount consists of a 3" diameter tube with parallel surplus 1" tapered aircraft control rod supported by four adjustable friction pivot supports. Each adjustable friction pivot is made literally from cannibalized microscope support stand parts. The adjustable friction pivots consist of two 1/2" SS cylinders with chamfered end with coaxially screw that bears against at right angles to a larger diameter rod as shown here:
Finally the binoculars are supported by a Thomas fluid filled camera mount as shown here:
Also note the Rigel Systems Quickfinder mounted on the 11x80 binoculars.
I have used this binocular mount for many years and it has worked very well.
Posted 20 August 2013 - 08:52 AM
Posted 20 August 2013 - 09:11 AM
What's the all-up weight?
Posted 20 August 2013 - 09:31 AM
Is that green finish a chromate primer?
I believe so. Came from the aircraft surplus on Sultana Ave down in Ontario that way. I typically have aluminum anodized though.
Posted 20 August 2013 - 10:21 AM
Wish I could work with metal as well as I do sometimes with wood.