Today's blog entry was supposed to be about our Strobist model shoot from last Saturday...however the only people to show up were Captura, Lumpy, and myself. The model backed out and the rest of the Strobists seemed to be lame ducks. So we ended up having a Strobist barbecue and spent the afternoon playing with Lumpy's new beauty dish.
Since I wasn't processing pictures Sunday it gave me an opportunity to complete at least part of a personal project I've been thinking about. Earlier this year I bought a D-focus follow focus. I admit that I bought it because of it's affordable price and not the performance. Of course, that alludes to the fact that this follow focus has a few issues because of affordability compromises. The first, and easiest one to solve is the stiffness of the backbone. If you look at the original using the link above you'll see that the backbone is made up of four parts: an aluminum sliding mount, two L-shaped steel brackets, and a small Delrin platform. The weakest link of these are the steel brackets. The brackets flex when you put any significant downward force on the follow focus knob.
Enter the improvement pictured below. I took these four parts and replaced them with a single aluminum sliding mount (not anodized in picture). It's super stiff and strong. Amazingly simply to build once I figured out the CAM programming on our vertical mill. I just need to get it anodized now. My build notes are sitting below the follow focus.
The next step? Improve the drive train. I'm thinking about adding sealed cartridge bearings and metal beveled gears, as well as improving some of the logistics of the design. That's going to take a greater effort, so another month and hopefully I'm there.