Stepper to Camera - Universal mounting plates
by limeyrock, published
A set of mounting plates and low profile modular dovetail adapters for attaching a range of cameras to a NEMA 17 Stepper Motor. Ostensibly for the purpose of creating a single axis gyro stabilised mount for all standard cameras. The 90 degree dovetails allow you to adjust the mount to adjust the axis of the lens to that of the motor, to avoid a swinging motion (or to add one, if that's your preference).
Inspired by Derek Leiber's awesome gyro mount for the Contour (http://www.revenanteagle.org/checksix/gyrocam/), I decided I wanted one that works on any camera up to small DSLRs, to this purpose I'm moving up to a NEMA11/17 stepper motor for extra torque, and building it as a universal system that could be used for other purposes, like automated panoramas.
Stepper motors are a bit jerky compared to servos so you'll ideally want a 1/16 microstepping driver like the Pololus used by the RepRap project. A 400 step (0.9 degree) motor should then yield a resolution of 6400 steps over the whole rotation. If this still proves to be too jerky a geared down stepper motor could easily be adapted (and provide even more torque).
UPDATE: The first draft of the 5mm shaft adapter is up, there have also been changes to the dovetails (some rounding and such). The motor mount has now been updated to use the mounting format of the other parts, this makes it possible to add an extra, positionable axis!
The male and female dovetail plates are joined to the shaft mount or themselves by epoxy glue or similar, using a short snip of 1.75mm filament in each of the four corner holes. These function as indexing and strengthening lugs. Being square they can either be built with the dovetails in the same direction or at 90 degrees to give two axis adjustment.
Still to come is a hollow to house an M3 nut between the plates so a grub screw can be used to lock them down.
The male dovetail is 0.25mm smaller than the female to allow easy mating. Still, I have found that they benefit from some smoothing.
It's probably best to print the dovetails with no bottom infill, to allow the epoxy to get a mechanical grip on the infill.