# Item needed



## Tex-Shooter (Dec 17, 2009)

Does anybody here have the ability to make a torsion spring like this one that is broke. It is 5/8 inch ID and had a total length of 5/8. The old one was made with 1/8 dia. wire. but I would like the new one to be 7/64 dia. As I don't need that much pressure. It is off of on of my paper cutters. I would trade a slingshot for it. -- Tex


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## Rayshot (Feb 1, 2010)

Hope you find a replacement quickly.


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## Thistle (Jan 4, 2013)

I just emailed a friend. He's in a meeting, but I'll hear something back later. If he can do it, we're happy to help. No freebies necessary--as tempting as that is. 

I'll post back if one of our forum members can't cover it, or if I get a positive for ya.


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## Thistle (Jan 4, 2013)

Will have a confirmed answer sometime later today, Tex.

I might require a repeat of specs from you just to make sure I'm not misunderstanding the parameters, but wait until I get a positive. Apparently there is more to these things than just a coil of metal.

Old Parameters:
Inner Dia 5/8 in
Outer Dia
Wire Dia 1/8 in
Body Length (length of the spring coil) 5/8 in

New Parameters:

Inner Dia 5/8 in
Outer Dia
Wire Dia 7/64 in
Body Length (length of the spring coil) 5/8 in

Number of coils
Deflection angle


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## Crac (Mar 3, 2013)

I think we are heading the right direction... "Yeh please don't copy a spring" maybe there is a moral relating to slingshots in there...

For starter I can give you some references:

Machine Elements In Mechanical Design, Robert Mott (2004)

MACHINERY'S HANDBOOK 27th ED (2004)

Mechanical DESIGN Engineers Handbook, Edited by Dan B. Marghitu

Shigley's Mechanical Engineering Design, Eighth Edition edited by Budynas−Nisbett

Standard handbook of engineering calculations by Tyler G Hicks

If you can find it, the 'Kemp's' book is an utter gem.

The topic is well covered in many books so finding the basic theory shouldn't be a problem. Note most of these books are a few years out of data. But the problem these days is everything gets buried in a CD or encrypted into Matlab so presentation is ****ed ... I mean 'thrown' right out the window.

I might look at this for giggles laters...

Mean time check out:

http://www.leespring.com/

http://www.leespring.com/uk_torsion_spec.asp?springType=T&forWhat=Search

I think you should be able just to buy a standard part... it would be quicker.


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## Thistle (Jan 4, 2013)

Tex, I don't have good news. Sorry. It's not possible to do the torsion spring. Like I said earlier, it's not as simple as it seems.

Unless someone here can provide exactly what you need, I'm going to suggest taking a look at McMaster-Carr. You can search torsion springs and narrow it down to deflection angle (the photo you've provided looks like a 270°) to see if they might have anything close to the parameters that you require. They also make 'custom' torsion springs. Usually those require a minimum order, and you only need one, of course.

If you can find your size that best fits your application, but let's say the legs are too long. You could still grind those down to the length you need. Might be the least costly way to go.

Torsion Springs


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## Thistle (Jan 4, 2013)

@Crac

Thanks for your suggestions. I'll add those books to my must-read list.


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## Tentacle Toast (Jan 17, 2013)

I don't know if it'd work, but might a spring from one of those hand grip squeezers work? Not sure about the diameter of the metal used, but I do know they're available with varying levels of resistance...they sort of look like the pic, too...


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## SHTF Slingshots (Feb 4, 2013)

I could ask my school's workshop teacher.
He makes metal and wood stuff.
I could ask if this spring would be possible for him to make for me.


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