Stabiliser Gimbal Design
August 2008 onwards

I have designed and constructed my own gimbal system, now much copied around the world. I see aspects of my design appearing commercially in the BLACKBIRD stabiliser. I initially experimented with ball joints, but determined that they would always be unsatisfactory for this purpose. I developed the idea of combining a small universal joint with a ball bearing. In my designs, I have usually placed the ball bearing below the universal joint, fixing it in the top of the handle. Other models have two bearings, one below and one above the universal joint. Around the universal joint shaft, in some designs, I have a small wheel which can control stabiliser panning.

Gimbal design #1, Autumn 2008

An early design. I felt that the yokes in this joint were not substantial enough.

Gimbal Design #2, March 2009

This design employs a Traxxas 1951 universal joint, or 'half shaft'. These are used in radio control model cars. This represents an improvement over the first joint I used in August 2008.

The Traxxas joint, left is superior to the red joint initially used. It is stronger and has lower friction properties. The Traxxas joint here has been pared down at the edges to improve the angles over which it operates. Sometimes these joints have an element of friction, and I have used a drill bit to ream out the locating holes in the yokes. This has removed a very small amount of material, but sufficient to make the joint virtually friction free.

Traxxas 1951 universal joint half shafts

The top of the joint is located in the gimbal housing. A collar, cut from the female shaft it located around this male end.

Gimbal Design #3, March 2009. A design with two ball bearings

Gimbal Design #4, July 2009. A stronger Traxxas joint and two ball bearings.

This is essentially a re-make of design #3, but using a more substantial joint - the Traxxas TRX-5151. In addition, I have taken measures to ensure a more accurate and adjustable alignment of the parts, and have allowed for easier disassembly. 4mm machine screws connect the ball bearings with the universal joint.

The Traxxas 5151 universal joint. This is a more substantial joint than the smaller 1951

Basic assembly using two ball bearings and a Traxxas 5151 joint between them. The top bearing is shown here with an aluminium ring around it for location in the gimbal housing.

Gimbal Design #5, February 2010

This gimbal is similar in form to the #4 design. The principal difference is that the top bearing can be locked. This means that the bearing will not rotate, and I can pan the stabiliser by turning the vertical shaft of the gimbal.

A Traxxas universal joint and two ball bearings. This assembly fits partially inside a metal tube which forms the gimbal housing. The slipping panning ring is fixed on the vertical shaft.

The horizontal 3mm screw can be screwed out to locate in the gimbal housing to stop rotation of the to bearing. The gimbal housing viewed from the top. Below, an external view showing the screw in the locked position.

Below, a illustration of the gimbal #5 mechanism - simplified and not precisely to scale. Shown with handle 30 degrees off vertical.

Panning Ring, January 2009

I have developed the idea of a ring fixed to the vertical shaft of the gimbal between the bearing and the universal joint. This allows the system to be panned without upsetting the level of the camera, but only with gimbals that employ a single bearing below the universal joint.

Friction slip ring, April 2009

This allows me to pan the stabiliser. Finger pressure applies torque smoothly because there is slippage. Achieving the right degree of friction is quite difficult. I found that too much lubricant can produce uneven results, and that just a trace amount is best - just enough to protect the steel from corrosion.

Panning ring design with pressure sensitive variable friction operation. February 2010

The slipping ring is intended to smoothly impart torque to make pans more even and controllable. The design employs a ball bearing with some of the balls and the cage removed. A metal washer is fixed to the outer race. Pieces of plastic tubing serve as spacers. Pieces of synthetic rubber sit between the races and serve as friction pads, determining the minimum level of torque transmission between the races. This level of transmission can be increased by applying, with the fingers, pressure along or across the axis of rotation. Without this pressure, the balls do not rotate, and serve only locate and guide the races. With pressure applied, there is increased engagement between the races and the balls. The balls now transmit torque as their rotation is resisted by the friction pads. This resistance determines the maximum degree of torque transmission.

Alternative arrangement for a slipping panning ring. A ball bearing, containing a specially formulated viscous grease, allows some slippage so that torque is applied smoothly. Finger pressure is applied to the outer race of the bearing. This is very useful where there is not much inertia around the stabiliser's vertical axis, and a very light touch is necessary for panning, as in stabiliser design #2.