Torsion springs

Electronegativity

I am comtemplating my first robot, and it seems like torsion springs might be a useful way to add flexibility to a joint.
They are the ones that look like a coils with the ends straightened out.

Does anyone know a good source for small (~1/8" - 3/8") torsion springs?
I tried a company called Century Spring, which has a great selection but wants 2 or 3 dollars for one tiny spring.
That is way too much, especially when I want to try out a bunch of different ones to see what could work.

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I wonder if this wire is hot...

Beau Schwabe

Your mileage may vary, but your general hardware stores are NOT created equal. I have seen several of these at one ACe
Hardware store and not any at another. Sounds like a good weekend to go hunting around your various local hardware stores.


www.vanel.com/torsion.php?lang=english&sessionid=24159966243100982dbbb7946592349731270204758585

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

LoopyByteloose

Make your own. Tiny springs are usually no problem as the bending can be done by hand. It is the big, heavy springs that need a foundry.

Get a vise and some appropriate spring wire from a hobby shop or piano tuner. [noparse][[/noparse]steel guitar string offers another choice]Take a rod of suitable diameter [noparse][[/noparse]or a bolt] and wrap it around the shaft for several turns. You can expect it to unwind a bit, so make the rod much smaller than the finished size.

Alternatively, set up a drill press at its lowest speed, put an appropriate drill bit in the chuck. Start the wire by inserting an end into the chuck somewhere and turning by hand until you get a few turns.

If that is not enough, turn on the power and carefully feed. You might find that you can do better without turning on the drill press and just doing the whole operation by hand. A lathe will work too, but most of us don't own one.

I really find that we neglect the mechanical side of robotics a great deal. As the robots get larger, suspension becomes important to reduce vibration and impact. Inflatable wheel barrow tires are useful. R/C Model airplanes have similar, smaller tires.

You can even heat treat and heat bend with a small torch - if you understand your metal and how to temper with oil or water.

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G. Herzog in Taiwan

Post Edited (Kramer) : 8/28/2005 3:42:20 PM GMT

Paul Baker

While I haven't specifically looked for torsion springs, look at www.smallparts.com . They have many small mechanical parts and may have what you are looking for.

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·1+1=10

Electronegativity

Good suggestions all around!

I decided to combine Kramer and Paul's ideas by purchasing wire from smallparts.com.
When it comes I will try to make the springs myself.

Kramer: I don't understand how to temper with oil or water.
Do you have any advice?

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I wonder if this wire is hot...