This is the build log for the 360° pan used on the Skywalker X8
(Click here for the Review video)
The goal with this setup was to get a really smooth, self centering 360° pan with great resolution. A pan that felt "natural" when moving, centered perfectly and had such high resolution that you can position it perfectly with the stick.
To achieve this I decided to use a 10 turn external potentiometer, modify a servo and gear it down.
This is the servo I used, a GoTeck GS-D9257 Coreless, digital, ball bearing tail servo.
The top taken off.
Most servos have some kind of mechanical stop that keep the potentiometer from being overturned and destroyed. Some servos have "better" stops than others. This particular servo has the "bad" kind of mechanical stop, in the form of "filled" in teeth on the gear.
I used a dremel with a cutting disk and simply made some teeth. It worked out great.
Some servos use the internal potentiometer as the stabilizing shaft for the output gear, which is not great as normal potentiometers have a build in mechanical stop. This particular servo didn't use the pot as a riding shaft. Instead the gear rests on ball bearings and all I had to do was to remove a little insert that connects the output gear to the pot and the problem was solved.
Normally the built in 1 turn potentiometer is used to sense where the servo horn is located. To get better resolution I decided to use an external 10 turn potentiometer. To connect this external pot I first had to desolder the old potentiometer.
For ease of installation I simply added a servo connector to the three pot solder pads. This way I can easily connect and disconnect the external pot without having to desolder anything.
The servo done. The 10 turn 5K linear potentiometer sitting in the foreground. (If you plan on doing this your self, make sure the potentiometer is a LINEAR not logarithmic)
Soldered the servo connector to the pot. The center leg is the important one to get correct. If the servo turns the wrong way you can simply swap the two outer leads by turning the connector around.
Hooked up some gear I had laying around for testing. When swapping the potentiometer in a servo always check the number of turns used on the pot by the servo. A servo never uses the whole range of the pot so this step is needed to figure out how many turns the servo defines as it's full range. In my case the servo only used 5 turns, which is half the range of the pot.
With that knowledge I went to the local hobby shop and picked up some gears. A Blade450 helicopter main gear which has 140 teeth and two RC car gears with 25 and 29 teeth.
I mounted the 25 tooth gear on the servo. This results in a gear ratio of 1:5.6 (The servo has to make 5.6 revolutions before the the camera turns 360°) The servo speed is 0.07 seconds per 60° of travel, which means that it's going to take around 2.5 seconds for it to make the camera go from looking straight back one direction to looking straight back the other direction. A nice, smooth speed.
I mounted the 29 tooth gear on the pot using a couple of brass tubes. The gear ratio on the pot is 1:4.8 which ensured that I got the full 360° range.
Time to make a simple mount.
A servo horn happened to have the correct hole spacing to use as the center piece for the main gear.
I used a 4mm screw and two ball bearings to mount the main gear to the tray.
Bottom view. The ball bearings ensure smooth, slop free movement.
A piece of balsa, zip ties and a Velcro strap mounted on the main gear to hold the gopro.
Tada! All ready to go.
Mounted on the X8
I'm extremely happy with the results. It's so smooth, precise and easy to use. Trouble is that it feels so natural to look around that I now miss having this feature on all my FPV planes.
Hope this guide was of use to you! Keep up the great suggestions.
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