Radio Controlled Cable Dolly for Small Format Cameras

Using some relatively simple construction techniques and off the shelf RC parts, you can make a small, fast, reliable cable dolly to carry a small format camera, and get you footage like this:

and this:

and this:

At lower speeds, it suffers a little bit of wobbling. Having a second person would eradicate some of this by enabling me to pull the line tighter; the rest, I can design out with the next version. I'm quite proud of having successfully sent it over a cliff! There are many problems I've already solved with various prototypes.

This instructable won't just show you how to make a cable dolly, it'll show you my research, errors and process too. By the end of it, you'll be able to anticipate common problems, and design one to work with whatever hardware you choose. There are many possible upgrades, which I talk about a little in step twelve. For now, I'm sticking with a simple cable dolly, with variable speed forward and reverse control.

After tools, materials and design, steps 5 - 9 will cover enough for you to make an unpowered gravity dolly, then we'll go into motors and radio control. Most prototypes of this dolly were made by hand with aluminium. The DXF used to make the CNC milled version is attached in step 5.

Step 1: Tools, Materials and Components.

A cable dolly, even a powered one, is quite a simple thing to assemble. Getting all of the little things right, designing and tweaking it to work well is the complex part. You'll probably run into all kinds of problems such as undesirable swinging, not enough wire tension, and insufficient contact between the drive wheel and the line. Don't be discouraged, you can iron these out.

I'm going to show you construction of my first ugly prototype, then take everything I learned to make a neat looking CNCed and improved version. In some steps, I'll be doing more than I really had to. This is either because parts were not available, or it was late, hardware stores had closed and I had to work with what I had to hand.

This instructable is focussed mostly on making the dolly with hand tools, since they're what more people have access to, but I did use some bigger machines to better the results and speed up the process. You can cut out a whole load more of those tools and steps if you have access to a three axis CNC mill.


Tools:

• Sharpie (for marking metal).
• Rubbing alcohol/Nail polish remover (for removing sharpie marks from metal).
• Battery drill.
• Hacksaw.
• Bench vice.
• Speed clamps.
• Metal files.
• Pair of adjustable spanners.
• Molegrips.
• Metric tap and die set (if making or adapting your own axles for pulley wheels).
• Soldering iron.
• Third hand tool.
• Wire snips.
• Wire strippers.
• Calliper (For precise metalwork, and determining your motor's footprint if diagrams aren't readily available)

Optional:

• Drill press/Pillar drill: Much more precise than than drilling by hand.
• Grinding wheel: If you cut down steel bolts, you could just file them, but this with the bolt held in molegrips is much faster and give a better finish. n.b. don't use this for aluminium, it'll clog up the wheel surface).
• De-burring tool: Easy to use, makes your metalwork much nicer.
• Benchtop belt sander: With the right belt, this can neaten up your cuts into aluminium no end.
• Lathe: For making wheels. You might be able to find stock ones you're happy with.

I used all of these things, and they made the job a lot easier.



Materials and Components:

(Not all shown in photos)

• Aluminium strip or polycarbonate sheet (4mm thick seems about right).
• L bracket and/or aluminium strip (to hold tripod head below dolly)
• Pulley wheels with axles.
  • Alternative: Nylon rod + lathe
  • Alternative: Inline skate wheels + lathe (This is what I went for).
• M3, M4, M6, M8 machine screws/bolts, washers, spacers and nuts (depending on the size and types of your wheels and motor fittings).
• 10mm aluminium square rod (Will vary according to the motor/mount you get).
• Threadlock
• Rapstrap (Soft, stretchy zip tie stuff. Not necessarily easy to find, but usually on ebay. Good for attaching stuff to the dolly temporarily).
• Compact tripod ball head (I favour the Joby BH1: Well built, compact, sometimes available for as low as £20, has quick release plates, and secure enough for small format cameras in most circumstances).
• 3/8"- 16 UNC bolt (To fasten tripod head to dolly).
• PVC clothesline (steel core), steel wire rope, or 5mm static line.
• Ratchet strap (For tensioning the line at each end).
• RC transmitter.
• RC receiver.
• Power source (LiPO or NiMH battery).
• Charger for battery.
• Electronic Speed Controller (ESC) with battery elimination circuit.
• Deans Connector if using LiPO and your ESC didn't come with one.
• Motor and gearbox (370 motors and gears are inexpensive and can shift relatively heavy loads).

Optional:

• Nylon bolts, nuts and spacers (For holding the body of the dolly together if using standard pulleys, extra fixings also give rigidity to polycarbonate body if you go that route. They don't necessarily have to be nylon, but nylon fixings are nice to work with by hand).
• Cable ferrules and thimbles (Vital if you're using steel cable).
• Sugru (If you're using a metal drive wheel and want to give it extra grip, though it's not made for this kind of application: higher powers will wear it away).

Comments

[oberpriller]

Great instructable. My only thoughts for improvement would be that you might be able to learn something from Kite and KAP (Kite Aerial Photography) sites regarding stabilization, balance, and attaching the rigging to a line. They seem to be dealing with similar concerns. I have seen a design similar to yours where one side of the bracket is removed to mount and dismount the camera rig to the line. However, kites deal with different line tensions.

[redsunmtm]

NICE, i am VJ, and was thinking making one of these, but i would deffinitely add pan, tilt and zoom, via wireless RS485 to be able to focus on a defined point while mooving ! (using an HD CCTV and RS485 controler) but sure, as i won't implement a way to keep that focusing point automaticaly (i don't know how to), i will need an extra help to control entire system :)

[kedwa30]

You can use a couple of foot pedals to control the cable dolly and that frees your hands to control focus, tilt, zoom, etc. Easy as riding a bike! :D
There might even be an 'ible on making your own pedals. Hmmm....
You could possible rig some Guitar Hero pedals to do the job.

[Nachimir]

Good idea. I'd love to give it a first person view and a gas pedal! :)

[AndyPipkin]

I was thinking about making one of these a while back from an old RC car, the idea was to hang it from my really long telephone line... but then I cut that down as it was in the way of rocket launches from the back garden, BT sucks and I'm on cable!!

[criggie]

What about twin parallel lines? There have also been remote controlled cameras at rugby games which run on two crossed cables.

[captain Jack]

nice project. I especially liked your "failures" section. Most projects people just write about the successes. Once can learn a TON from the failures, too!
Well done.

[FuzzyBearGeek]

Yes!!!
very nicely done!

[JamesRPatrick]

I tried making a similar dolly(unpowered) using channel Al and steel wire for the line. Those things sure do make a racket when you play back the video. I also found that the thing was a pain to aim/balance.

By the way I really like the wheels that you made.

[batman96]

I believe in the go pro video the gyroscope is connected to the wheel, so that it serves dual purpose, both as a gyro, and as a device that keeps the camera dolly from going over a certain speed.

[Nachimir]

Oooh, that's a really interesting idea. Thanks.

[stephenniall]

Definitely will be making one of these ! Probably not an RC Version though.

I'll post a video of the footage took with it, Although weather Permitting in sunny britain...

[Nachimir]

Tell me about it. I'm trying to get outdoor shots at the moment, but it's too windy :)

[1dog789]

if there was a master title you have surely earned it