The View Up Here

Random scribblings about kites, photography, machining, and anything else

Interchangeable KAP Bits

Posted by Tom Benedict on 29/05/2014

Now that the aimable helmet camera is finished I’m on to the next project: interchangeable KAP bits.

A kite aerial photography rig is made up of two main parts: a suspension and a camera mount. The suspension is the bit that connects the KAP rig to the kite line. The camera mount is the bit that holds the camera and lets the photographer aim it at the subject. Each of these can be as simple or as complicated as the rig builder wants them to be. In previous posts I’ve talked about a number of ways to over-complicate a camera mount. In the near future I hope to come up with some new ways to over-complicate the suspension. But in order to do the testing I want to do on the new suspension I need a way to swap one rig between a Picavet, a pendulum, a handheld pole, or what have you. This is what I came up with:

KAP Suspension Connector

I made these out of 3/8″ 6061 aluminum round. Square stock would’ve worked just as well and wouldn’t have required a lathe. The two bits are threaded to go onto a Brooxes Better Gear Guide pan axle and to take a Brooxes Picavet. Both of these use #8-32 screws. I used the same screw thread for the two screws that hold the two parts together. There’s nothing magic about the #8-32 screw. If your rig uses metric hardware you can use metric hardware for this part as well. M4 is a good size.

This probably would’ve worked with one screw, but I like backup when it comes to KAP rigs. Having a camera fall out of the air is never a good thing. Besides, by using them in opposition like this I was able to design the parts to be identical regardless of whether you’re talking about the camera end or the suspension end. The two halves are entirely interchangeable. In both cases the outboard hole is tapped #8-32, and the inboard hole is drilled for tight clearance on a #8-32 screw.

Between the two screws is another hole. I originally designed the hole to take a 1/8″ dowel pin, so these are drilled a few thou under the 0.1240″ diameter of my press-fit reamer. The idea was to ream one as a press fit and the other as a slip fit. But in the end I decided the dowel pin wasn’t really necessary, and having pins in some of the parts and not in others would’ve broken the nice symmetry I’d built into them. Which leaves the question: what to do with that hole? Easy! Safety tethers! Now there’s even more safety in case both screws fall out.

I’ll have the opportunity to try these out during World Wide KAP Week 2014. Meanwhile I’m building a slightly beefier version of this to use on the end of a 25′ painter’s pole. Once that’s done I’ll be able to use the same KAP rig on a Picavet, a pendulum, or a pole, just by popping out two screws.

– Tom

P.S. I typically write a post over the course of several days, editing at the beginning of a writing session and writing during the second half. In the middle of this post’s write/edit cycle I was approached at work about the possibility of doing some still photos using a cable cam. Only problem: we don’t have a cable cam at work. Hey, no problem! The suspension on my KAP rig is now interchangeable! So swapping it over to whatever cable cam system we build is a no-brainer. YAY!


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