I was familiar with the adjustable coolant hose systems used to spray coolant at cutting tools in the machining industry and thought that would be a great place to start. I ordered various nozzles and hose segments from my favorite online machine tool supply company and started experimenting. This is what I came up with. While it still has plenty of room for improvement it has served me well over the last 3-4 years.
These arms can be placed into pretty much any position and they will stay there.
Another nice feature is that you can make all sorts of attachments for holding whatever you need to work on. So far I've made a circuit board holder, a clamp, a mount for an LCD, and an extraction fan for keeping fumes out of your face.
All you really need are some simple hand tools, a couple taps, a drill bit and a drill to make the basic version. If you have all the tools you need, it can be made for $20 or less.
Step 1: Getting Started
- Drill (A hand drill will work but a drill press would be better.)
- 3/8" drill bit
- 1/8-27 NPT tap
- 6-32 Tap
- A tap handle
- Center punch
Don't forget safety glasses!
- The Base:
I used a block of 1/2" thick aluminum (5.75"x2.5"x0.5"). Aluminum is heavy enough to be stable and is easily tapped. You can use whatever you want as long as it is at least a 1/2" thick and can be tapped. (Plastic, wood, MDF, steel, etc...) The lighter the material, the larger the base needs to be in order to remain stable. If the material is too soft the threads will wear out and the arms won't stay in. If you don't have a local source for the aluminum you can order it from an online metal sales company cut to length for about $6 plus shipping. I have used www.onlinemetals.com for other projects in the past.
- The arms:
The arms are made from coolant hoses and nozzles used in the machining industry to keep cutting tools cool and lubricated. I used the Snap Flow brand coolant hose system which I bought from www.use-enco.com. They sell a "Male NPT Hose Kit" that has 13" of hose and an assortment of nozzles and connectors. That gets you most of what you need to make a two handed Third Hand. I'd recommend buying two kits and a few extra nozzles and connectors. For around $12 you will have more than enough parts to make 4 arms.
For each arm you will need:
- One 1/8 NPT connector
- 4-5" of hose
- One 1/8" 90 degree nozzle.
You may want to consider buying the hose assembly pliers for $23. They are a little difficult to snap together by hand. I didn't buy the pliers but I kind of wish I had.
- The Hands:
Each hand is made out of a banana plug threaded into the 90 degree nozzle and an alligator clip. I chose the "Flexible Banana plugs (2-Pack)" from radio shack because it has 6-32 threads that will thread into the nozzle. The alligator clips are the standard 2" size.