Documenting the mundane - part 3

In film the focal plane moves with the action, and sometimes without for effect. I really like this look and as I don't have a video camera I tried to achieve it in a time-lapse video.

I found that no matter how quick or slow I wanted the focal plane to move, it had to be made via completely even steps. Of course as I was doing this by hand it was very difficult. Just like a panning camera, the movement of the focal plane looks abrupt and jittery if it is not completely even. I expected I would be able to make a small change every other shot but this is not the case.

The best option would probably be to continuously turn the focus wheel with a very slow motor. I have since tried this with various small motors attached to elastic bands and have found that none of them deliver enough torque. On my most flimsy lens the focus wheel almost moves how I want it to, but it seems the elastic band absorbs the tension up to a point, then twists the focus wheel, then the process starts again. I don't want to get into chains and what not and so am trying to come up with some kind of string that is perhaps everso slightly elastic and abrasive enough to grasp the focus wheel. If I can get this balance right I may be able to get the results from one of the small motors I have already been playing with.