Back in 2011, I built a DIY motorized time lapse dolly that would work on a standard extension ladder.  I used some standard skate wheels, some plywood, and a few parts from  The biggest problem was portability, and I wanted to be able to use different ladders.  I have 2 extension ladders, but they are not standard width.  I also have access to a third extension ladder at my 2nd job that is also a different width.  I had ideas in the past on how to resolve this, but not until I saw the new Actobotic parts from ServoCity that I figured out a better solution.  Here are the links to my original build.  You’ll see that I have recycled some of the components.
Here is the completed dolly with attachments for multiple cameras.  I will normally only use 2 cameras on the rig, but thought that I would show how versatile the Actobotics channels are, as you can use multiple camera mounts.
The Actobotics 1″ Tube Clamps, I was able to use PVC pipe in the structure of the dolly.  Loosening a couple of screws allows me to adjust the width of the dolly to fit onto different extension ladders.  You could technically use other rails, such as 2×4’s.  Once I figure out the maximum width of my biggest ladder, I’ll cut off the extra PVC, but you can at least see that with the current configuration, I could go a couple of feet wide.
Parts list:
3 x 15″ Aluminum Channel (585458)
1 x 1.5″ Aluminum Channel (585440)
1 x Channel Bracket A (585484)
1 x 90 degree Single Angle Short Channel Bracket (585506)
4 x Center Hole Adapters (633118)
1 x Quad Hub Mount E (545452)
8 x 90 Quad Hub Mount D (545324)
12 x 90 Degree Quad Hub  Mount (545360)
2 x 90 Degree Dual Side Mount (585470)
1 x 90 Degree Hub Mount B (545404)
2 x 3/8″ Bore Pillow Block (535154)
1 x 0.5 RPM Gear Motor (638142)
4 x 1/4-20 Round Screw Plates (54546)
5 x 1/4″ 6-32 Socket Head Machine Screw
8 x Dolly Wheel Drive Plates B ( 585536)
8 x 90 Degree Quad Hub Mount B (545424)
8 x 8mm Flanged Standoff A (585488)
10 x Aluminum Clamping Mount (555116)
2 x 3/8″ Aluminum Set Screw Collars (9946K13)
2 x 1″x2′ PCV Pipe
1 x 12V Rechargeable Li-ion battery
I reused the skate wheels, bearings, and gear sprocket from my old dolly.

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