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This is a DIY camera stabilizer in form similar to the MERLIN. I used mostly scrap or surplus materials. A piece of 1/8 inch aluminium forms the camera platform. Below that, separated by spacers, is a slotted aluminium plate to which the gimbal housing attaches, allowing front to rear balance adjustment. An aluminium torch was reconfigured to act as a handle. It's not an ideal shape for the hand, but the head allows the ball bearing of the gimbal to be held in place satisfactorily. A curved aluminium tube screwed to the camera plate holds the washers used as counterweights. The pictures here represent experiments over a period of time, and dimensions and balance configurations are different from time to time. For these experiments, I have been using a Panasonic NV-GS60 camera weighing a total of 600mg (1.3lbs) with the large battery attached. The whole system weighs about 3lbs. I have positioned the gimbal some distance below the camera to maximise the inertial effect of the camera's mass. The different heights of the counterbalance weights cause unequal centrifugal forces to be experienced by the system, and can cause tilt when panning.
Aerodynamics. July 2009 With the stabilizer so finely balanced, and the gimbal so low in friction, even a light wind can cause instablity, producing tilt and rotation. Wind coming from the front or the rear impacts on the screen, and this is difficult to compensate for. However, this is not too much of a problem, as my body shield the system from wind coming from the front or the rear.. I could never compensate for all air turbulence, but in a steady breeze, this modification is very useful.
Static & Dynamic Balance
The orange dots indicate the principle centres of mass of the camera and the counterweights. The yellow dot indicates the centre of the mass of the stabilizer with no counterweights or camera. .The green dot indicates the centre of the universal joint. The system is shown against a 5cm grid. In this setup, the camera has a mass of 500gms. The forward counterweight;s mass is 170gms, and the lower weightt's mass is 210gms. The remainder of the stabilizer (excludind the gimbal and handle) weighs 320gms, and its overall influence on the balance in this setup is relatively small, although not insignificant. The masses of the camera and counterweights (m) and dimensions (L) are represented in the diagram. I have excluded the mass of the stabilizer framework .During panning, the centrifugal forces of m1 and m2 will cause tilt in a contrary direction of that of m3. For dynamic balance, we want (m1 L1)+(L2 m2)=m3 L3. If these forces do not balance, the stabilizer will tend to tilt during panning. The above is a highly simplified representation of the dynamics. Interesting Tiffen Steadicam analysis of balance dynamics here
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July 2009
I have removed an earlier sliding balance weight in the plastic channel, and replaced it with a threaded wheel on a 4mm threaded length. The wheel has the outer ring of a ball bearing sandwiched between two UK pennies which have had the plating rubbed down. Inside the bearing ring, I have lead, as it is a heavy material.. I cut the supports from a transistor heatsink, and tapped a thread through the disc. This necessitated the repositioning of the rear spirit level. Gimbal modification. April 2009.
This coupling allows the panning ring to 'slip', allowing smoother pans. The vertical shaft of the gimbal is fixed to the centre ring of a ball bearing, and the outer ring is actuated by hand. Three short sections of soft plastic sit between tthe inner and the outer rings, and provide the necessary friction. The plastic grips the outer ring, and there is movement between the plastic and the inner ring. The ball cage has been removed. There is no lubricant in this design, other than a trace film of oil. Too much oil or grease produces inconsistent friction.
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I have designed and constructed my own gimbal system. I experimented with ball joints, and initially used one which I made up myself. It was good - smooth and fairly low in friction, but I was never really satisfied with it. Eventually I had the idea of a small universal joint combined with a ball bearing set into the top of the aluminium torch (flashlight to our American friends) which forms the handle. The bearing is a standard skateboard type - available quite cheaply in packs of ten. Conveniently, the head of the torch dismantles, allowing the bearing to be fitted in a very satisfactory way. The ball bearing is held in place by a threaded ring. Above the bearing in one design, I have a small wheel which will pan the camera with minimal effect on the camera's tilt. Using a finger on this wheel, I can also effectively lock rotation on the vertical axis to the handle, and contol pans by turing the handle. If the vertical shaft is off-centre in any way, the camera may display a tendency to turn when the handle is tilted, so some accuracy in construction is required. This is less of a problem with the ball bearing located above the universal joint Later designs use two bearings - one above, and one below the universal joint. Gimbal design #1
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.
I have tried replacing the original grease in the bearing with light 3-IN-ONE oill. This reduces friction in the bearing, but I'm not sure that it is appropriate for this application. It seems to produce uneven results. Gimbal Design #4 July 2009
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. An aluminium ring around the top bearing (shown on the left) aligns it with the interior of the gimbal housing. 4mm machine screws connect the ball bearings with the universal joint.
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