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.
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.
- Sharpie (for marking metal).
- Rubbing alcohol/Nail polish remover (for removing sharpie marks from metal).
- Battery drill.
- Bench vice.
- Speed clamps.
- Metal files.
- Pair of adjustable spanners.
- 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)
- 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.
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).
- 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).
- 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).