Continuous rotation pan-servo hack

The ratchet pan system needed constant adjustment to keep operating so I decided to change to a continuous rotation pan servo with gearing.

Servos are designed to rotate +/- 30º to 45º but with a simple hack they can be made to rotate in either direction continuously. All that's required is to open the servo, cut out a couple of little plastic tags and drill out the inside of the lower part of the spline. Here's a full explanation of the hack from the KAPER e-magazine.

Gearing down is a good idea to reduce the speed of panning, so a large gear on the pan bolt is meshed with a smaller gear on the servo. This rig used 2:1 ratio but 4:1 is recommended.

One issue you may need to deal with is servo creep. Some continuous rotation servos will not stay stopped no matter how much you adjust the trim switches. James Gentles makes an antiCREEP unit that solves the issue for standard servos. It gives a wider "no movement" zone and slower rotation overall. Unfortunately I found the hacked Turnigy servos did not work well with antiCREEP. The "no movement" zone became too wide.

This three legged rig with continuous pan micro servo and standard tilt servo weighed 560g all up, but suffered from pan servo creep.

Another issue with continuous pan is that you can easily lose track of which way the camera is pointing unless you use a video downlink (extra weight and expense) or some sort of pointer on the rig that is visible from the ground.

KAP rigs - RC Carbon fibre tube

The Flickr KAP gear group is a fantastic resource for researching rig designs. There are many different styles of backyard and commercially made rigs but the one that really caught my eye was this one by Eric Kieboom.
Made for the Lumix LX3 using 4mm carbon fibre tube and various aluminium profiles it weighs almost 300g lighter than my first effort. As soon as I saw it I decided to ditch the heavy al rig and use carbon fibre tube. Back to the shed.

Lumix LX3 Carbon fibre tube RC rig - 600g

Here is my first version. The biggest challenge was finding the small aluminium extrusions. The square profile used on Erics corners and pan bolt support was not available in Australia. So I used 10mm tube which made accurate parallel drilling very difficult. Carbon fibre tube is available from Carbon Fiber Australia through their online store. 4mm x 1m tube A$5.95 each plus A$10.45 post.

Eric used CA glue (superglue) but I had some problems getting good adhesion so changed to epoxy.

I also bought a 4ch 2.7GHz radio from Hobbyking.com for A$28 (it works perfectly!) and added a mini servo for the shutter. The plastic mount for the shutter servo slots into the camera hotshoe and flexes when the servo pushes down. This prevents over stressing the servo.

This video shows it in action.

All up weight now 600g with 4 x AAA batteries. More weight could be saved by using mini servos.

KAP rigs - RC 3mm aluminium

At the other end of the complexity range is the full radio controlled rig which is heavier than a manual rig because servos, receiver and batteries are included.

Panasonic Lumix LX3 Aluminium RC Rig - 745g

This was my first RC rig, made from 3mm x 35mm aluminium resulting in a flying weight of 745g. (Flying weight includes everything hanging from the kite line)

The LX3 does not have an intervalometer or IR remote so the only way to shoot is by pushing the shutter button.
My existing Futaba radio was only 2 channel but I needed tilt, pan and shutter control. I devised this system using one servo for two controls, down to move the pan ratchet and up to shoot, with the other channel for tilt. I used standard Futaba S3003 servos and 4 x AA batteries resulting in a rig that worked but was way heavier than it needed to be.

A stiff breeze was required to lift the rig with  constant tweaking to keep the pan/shutter link working.

Building this rig was a good learning experience. The first lesson learned was that 3mm Al is way too thick. 1.6mm would be plenty strong enough.

Soon after completion I saw a carbon fibre tube rig and decided that was what I had to build next.