A HoVer KAP Rig


This page describes a HoVer rig for Kite Aerial Photography. An Arduino-based TX for it is described here (using 4:1 geared Pan Servo) and a TX with AUTOKap capability here (360° Pan servo).

The rig is essentially the same design as Cris Benton's latest rig (for his EOS M3) which you can see here. Since I had access to a laser-cutter, I cut most of the parts either from 3mm plywood or 3mm perspex (a.k.a. lucite or plexiglass). Windows Meta File plans for the rig parts can be downloaded here and the picavet parts here.

Here are photos of the finished parts and the partially-assembled rig (wiring not tidied up) along with the controller:

and here are diagrams showing the various parts that make up the rig and how they are put together:

and finally a list naming them:

  1. Hover bearing holder (2 off)
  2. Tilt Frame (two off)
  3. Pan Frame (holds tilt servo)
  4. Pan Frame tube strengthener (3 off)
  5. Pan frame tilt servo inner support
  6. Hover bearing inner (2 off)
  7. Pan frame tilt servo outer support
  8. Pan axle frame (2 off)
  9. Pan frame switch support
  10. Leg support (2 off)
  11. Tilt axis strengthener (3 off)
  12. Pan frame
  13. Camera support plate
  14. Pan and Hover servo tube supports (8 off)
  15. Tilt servo horn plate
  16. tube support strengthener (8 off)
  17. Hover axle gear (32 teeth)
  18. Hover servo gear (32 teeth)
  19. Pan servo gear (64 teeth)
  20. Pan axle gear (16 teeth)

The AutoKAP rig uses two 32 teeth gears (same as the Hover axle/servo) for the 360° Pan servo.

Some Construction Notes

I used 7.5mm Exel carbon-fibre tubes to hold the main and tilt frames together and the corresponding holes in the wooden parts are a tight fit for them (they needed a bit of reaming to allow the parts to slide). The pan frame tubes are 175mm long and the tilt frame tubes are 160mm. The legs are 6mm Exel tubes 180mm long.

The slots for the servos in parts 5 and 7 and the servo tube supports (part 14) are designed to fit TowerPro MG90S metal-geared servos). The holes in two of the gears (parts 18 and 19) are designed to take the servo horns for these servos as a push fit. The horns can then be screwed to the gears.

I used two small ball-bearings (4x12x4mm) to hold the HoVer axle - the two bearing holders (part 1) are tailored to fit these.

The one handmade part is the aluminium bracket that holds the camera. It was designed so the tilt/hover frame is properly balanced. The diagrams below show the key measurements but note that they are specific to an EOS M carrying the pancake lens (not the 18-55mm lens that Cris uses).

The picavet shown below is also made out of 3mm ply - two pieces glued together (necessary because some 3mm ply is too flexible and snaps under stress).

Weight of the Rig

Here's a table of the weight of the various components in grams:
Rig 170
4AAA battery 50
2.4GHz RX 10
5.8GHz Video transmitter + camera cable 42
Picavet (including hangups) 36
All-Up weight of rig 308
Camera (including pancake lens) 396
Take-off Weight 704

Version History

Comments, suggestions and bug reports welcome. Dave@zenoshrdlu.com.

For other SDM and CHDK-related stuff of mine, see here and here.