This is a rather ambitious project and by ambitious I mean it might not work. On many occasions I have needed to adjust the height of something, usually a camera, in very fine increments. A tripod works really good for that and I have one... but a lab jack would be much better so I decided to build one. Also a lab jack is a nice thing to have!
There are three industry standard approaches to designing a lab jack. One is THIS where there is a scissor lift that has to slide in a track relative to the platforms. One disadvantage is that it becomes less stable as the height grows. Another design is the Dual Pantograph like THIS that is a bit more stable but requires a lot more linkage's. A much more stable design uses three linkage hinge's in THIS type of configuration. With this one there are two opposing linkages and a third to add stability. This last configuration is what I decided to build.
|Homemade Lab Jack|
The above picture shows how much progress I have made at this point. Not much! You can see the opposing hinge systems and the location of where the third will be. The wood that I am using is Baltic Birch plywood, the same wood that I used in my clock. There is a 1/4-20 all thread bolt running through the hinges and that was the tricky part of this project.