Public Lab Research note

Pierre's plastic Picavet

by cfastie | April 15, 2014 16:19 15 Apr 16:19 | #10311 | #10311

I have been positioning the Redstone Rig as an upgrade to the soda bottle rig for holding cameras for aerial photography. By itself, the Redstone Rig allows easier mounting of the camera, more reliable aiming of the camera, better access to the camera controls and LCD, and modular attachment to different suspension systems.

A Redstone Rig suspended from a kite line by a Picavet system.

When the Redstone Rig is paired with a Picavet suspension system, there are additional advantages. The Picavet system was first described by Pierre Picavet in 1912, but was little used until its rediscovery was described in a 1988 article. It is now the most popular camera suspension system for kite aerial photographers. The Picavet has two points of attachment to the kite line and thereby reduces swaying along the axis of the line. The suspension has four points of attachment on the camera rig, and thereby greatly reduces rotation, or spinning, of the rig. The suspension lines slide freely through the four attachment points, and this allows the hanging mass of the rig to keep itself level even as the angle of the kite line varies. This combination of damping and leveling provides a much smoother flight in typical kiting conditions, and results in more photos of the intended subject and much less motion blur.

Sketchup was used to design the cross. The star on top allows the shaft to be locked in eight positions to aim the camera.

The Picavet cross I designed for 3D printing is about 8.5 inches long. It has a long and a short dimension, and the rig tends to be more stable when the long arm is perpendicular to the kite line. A short shaft below the cross serves as a moment arm to help the mass of the camera level the rig. The shaft attaches quickly to the Redstone Rig with two cotter pins. A star of slots at the center of the cross allows the rig to be pointed in any one of eight directions for aiming oblique photos.

The Picavet Kit includes the 3D printed cross and all the hardware to assemble the system and attach it to a kite line.

Files to print your own Picavet cross are available for free download at Thingiverse. Tips for printing are here. A kit of the required hardware for building the system is available at the KAPtery, and a complete kit including the 3D printed Picavet cross is available. A parts list and assembly instructions are also available.

I just manufactured a bunch of these laminated carbon fiber shafts which will be included in the full Picavet Kits.

Assembling the kit originally required lots of epoxy and some careful drilling to make the 12 cm laminated carbon shaft. I have made several of these and am now including them ready to go in the full Picavet kit. Assembly now involves mostly screwing in four eyebolts and threading the Picavet line. The $10 hardware kit (without the 3D printed cross) still has the parts for the shaft and requires gluing and drilling.


I've tried printing this rig a few times now and every time, now matter how I set it up first, it always comes out at about a quarter inch? I've tried rescaling it in Sketchup, and Tinkercad plus in Repetier and Cura. I always make sure to convert to Millimeters first and ensure it fits on my build plate. Yet it always comes out like it was designed for Smurf Kites...

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I'm not sure what the problem is with that Picavet model. It was designed in Sketchup, and it is scaled correctly in Sketchup, so it is 22 cm long. But when it passes from Sketchup to Meshlab to Netfabb to Makerware, it becomes 8.7 mm long. That's not a problem in Makerware because it lets you enter an absolute dimension. So I make it 22 cm long and all is good. This happens with other models too. I don't know what I would do without Makerware's ability to apply an absolute dimension. I can send you the model in another format, but I don't know what you can use (Sketchup [skp], Collada [dae], Makerware [thing]) or whether it would help.

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