expandable wiring

Is there such a thing as expandable wiring? We have an expandable arm and we need to run some pneumatic 4mm tubing and wiring up to a motor on the end of our arm. Or arm extends about 3’ and we don’t know how to run our tubing and wiring up to the top of our arm. Any advice?

You could coil your tubing using a heat gun and piece of pipe then ziptie the wiring to the tubing.


For the pneumatic portion, squirrel has a great idea below my post.

For the elctrical portion the following applies:

The only effective way of dealing with this scenario that my team has used in the past is to have as much cable as you need to use to extend the full length, and then arrange it (very neatly) in some wire loom material or whatever so all the cable is covered from damage, and then use some sort of spring (surgical tubing or whatever) to hold it so it stays in a safe place when your arm is retracted to the minimum length.

Basically do anything that works, but also keeps the cables away from any pinch points, and use enough cable to not pull the cable out when you are fully extended.

I don’t know of any cable that has “bungee” qualities as of yet.

And, this is not only coming from a team standpoint, but from someone who works in a cable assembly department at an Engineering firm.

We use so many cable types, it’s unbelieveable, but as I said, nothing meets that magic “bungee” requirement that would be the best way to run cable.

Interesting idea, coiled plastic air hoses are pretty common, why not make your own?


Our Triple Play robot had a similar design problem. After much debate and trying a lot of different ideas, we ended up using a retractable lanyard mounted to the arm just behind where the extension began. We had a couple loops of wire & tubing attached to it together. The loops allowed us to get 3’ of extension from an 18" lanyard. It worked very well for us. I could only find a couple of pictures of it, but hopefully they give you an idea of what we did.



Also consider using the igus “energy chain” from the KOP

You can use surgical tubing to fold the wire bundle as the arm retracts. A few short pieces work better than one long piece. It the tubing proves to be too strong, you can cut it length wise (using one half or one quarter the circumference). This is more commonly known as “accordian” because it looks and acts like an accordian when the arm retracts.

you can purchase coiled tube for pneumatics we are using it and it works great from mcmaster-carr

we just left from our workplace, and we discussed how we were going to run the wires and hoses to our manipulator, and we decided that the energy chain would work really well.

We have the same problem, but we are going to go with the IGUS chain that came in the kit of parts. It does a great job if you mount it correctly and it has enough space to fit the pneumatic tubing.

Look at your telephone cord…


yea, we will be going with coiling our tubing and wiring around something springy, maybe a slinky. But to bad they haven’t developed some wireless wiring, or a tiny compressor that is only 1 inch square.

also look in the box of leftover pneumatic parts from last year, there is a red/blue coiled pneumatic hose assembly! this won’t help rookie teams this year, though.

my team is thinking about using a tape measure like device where it retracts onto a spool when our arm restracts. Our arm reaches about 8 feet, so ours would need to be a bit more extensive. And we have 48 hours till ship.


The real easiest way to make a coiled pneumatic tube is to wrap it around a steel rod of the right diameter, nice and tight, and then submerge it in boiling water for 10 minutes or so. Comes out looking just like the stuff from McMaster. We do ours in the school chem lab every time we need coiled tubing.


Teams have used this type of device in the past. The ones I have seen are commercially available cable reels. You can easily make your own by using a spring driven drum, and attach the midpoint of your wiring to the drum and place the drum so it is halfway up your elevator when it is fully extended. As the assembly comes down, both the upper and lower portions of your wiring will wind onto the drum. If you must keep the drum mounted on the robot and only pay out wire as the elevator rises, then you need a device that has an internal slip ring assembly.