This project was completed in May 2005, which predates my ownership of any digital camera, so be prepared for a lack of photos. I'll try to take some next time I have an opportunity to set up the jib.
My goal with this project was to build a small, inexpensive camera jib for use in independant filmmaking. The final cost of the BOM worked out to approximately $600 which is substantially cheaper than most equivalent entry-level jibs. This included four gear motors (only two of which were ever used), two two-motor motor controllers and AVR prototyping gear but did not include the cost of a Bogen tripod base which I borrowed from my university for this project or an assortment of ball bearings, shafts and other bits salvaged from several disassembled vintage Kurzweil document imaging systems. If you built this project without motor control and used thinner aluminum stock, it could probably be done today for less than $500.
The jib's base was built from a 6"x6" aluminum plate with an L-bracket bolted to the left and right edge. Two holes were drilled through each L-bracket, one at 3" above the base and one at 6" above the base, and fitted with ball-bearings. The bearings chosen had a flange that allowed them to be press-fit into the holes and secured with small screweheads that overlapped the flange. Not exactly precision engineering, but it worked.
I had originally intended to attach motor-drives for jib-arm pitch and yaw to the base. I built a mounting bracket for the pitch motor using a 2"x2" L-bracket, but never completed the control system to drive it. In hindsight I suspect the moment of inertia for the arm, even properly balanced, would've been too great for the cheap gear-motors I was using.
As with many budget camera jibs, my design used a parallelogram structure to hold the camera head in a fixed attitude relative to the ground. The bottom strut consisted of two 6' long, 2" square, 1/4"-walled aluminum square tubes joined together by a 1-1/2" square x 1' long aluminum blank. The bottom half of the strut mounted to the base at the 3' mark and had a steel tube for holding counterweights at one end; the top half of the strut had a pivot for the camera head on top. The top strut employed similar construction but used 1"x 1/8"x6' square tubing.
I constructed the camera head bracket from several pieces of 1" square tube left over from the top strut. I had originally planned to weld two 6" pieces of square tube together to form the bracket but ran into trouble with TIG welding aluminum -- it is not for the faint of heart, even if you have an experienced TIG welder mentoring you. In any case, the finished bracket was drilled to accept two bolts along the vertical portion which fastened it to the top ends of the upper and lower jib arm struts. The horizontal portion was drilled to accept another motor mounting bracket and the vertical driveshaft for the camera pan functionality.
The actual camera head consisted of two large L-brackets (6"x3" arms, 1/8" thick) connected by the tilt driveshaft. The top L-bracket mounted to the pan driveshaft and held the tilt drive motor and bearings; the bottom L-bracket mounted to the tilt driveshaft and was drilled to accept a standard camera mounting bolt.
My initial build suffered several serious design flaws: First, the gear motors I'd used to pan and tilt the camera head were far too loud to permit use during sync-sound recording. Other users have solved this problem by employing cable drive or hydraulic actuators. Additionally, I was unable to source suitable rotational encoders for the pan/tilt head and did not complete the AVR firmware intended to control same. In operational use, the camera head was driven by a simple switchbox. Since the pan/tilt features could not be used while filming due to the loudness of the drive motors, this in itself was not a major limitation.
Design ©2005-2007 R. Spicer / Alterscapes.
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