# Spring steel?



## Baldhead (28 May 2013)

Hi

I need to make a small spring as in the picture, what sort of metal do I need?


BH


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## marcros (28 May 2013)

Spring steel!


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## spinks (28 May 2013)

You can just use mild steel round bar of the correct diameter but it would need tempering afterwards....I am sure you could buy a spring of the correct size for not alot of cash on ebay or similar......If all fails drop me a message I have a friend who works quite high up in a big spring firm and I am sure he could "acquire" something for me to send you!!


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## Limey Lurker (28 May 2013)

I'm pretty sure that you could find a small-engine valve spring that would fit.
(You can't make springs with mild steel; you'd need tool or silver steel which would need to be 
annealed, shaped(coiled), then re-hardened and finally tempered.)


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## DonJohnson (28 May 2013)

Mild steel will not be much good for making springs. 

The correct material is Patented Carbon Steel Wire - sometimes called Piano Wire or Music Wire. After winding the coil around a mandrel of suitable diameter, the spring will need to be heat-treated at 250 degrees C for about 30 mins, and allowed to cool *without* plunging into water or oil. (Spring Steel is used for springs made out of flat material, and usually requires hardening by heating to red-heat and quenching in oil, then tempering to 'blue' or 'straw' colour followed by air-cooling)

Note that there will be some change of size after heat-treatment - to make a single spring would take even an experienced 'hand coiler' several trial runs to get the sizes exact, so if you can buy a box of assorted springs and find one that does the job it would be a lot easier.

If you *have* to make a 'bespoke' spring, and can calculate the force - or 'load' - at a couple of positions, you could use a program I wrote many years ago to find the correct size of wire, number of coils, etc. for the diameter needed.

It is still available to download on my old company's web site at http://www.goss-springs.com/spring_program.html - click on the picture of a spring, and run the .exe file that downloads (You may need to download the VB40032.DL file also).

The program will give an indication of whether the spring is viable - i.e. whether the stress at each loaded length is within limits for the material, and whether the 'solid' length (when totally compressed) is less than the shortest loaded position.

The program also can calculate for tension and torsion springs.

I hope that someone might find the above useful, but if not, this reply gave me a chance to show off some of the knowledge I gained whilst working at a spring-making company for 30 years !


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## Richard T (29 May 2013)

Thanks to people like Don it is very easy to find coil springs ready made. Much easier to search for one of the right dimensions (I'd start with ebay) than to attempt to make one. 

+6 mild steel is not heat treat -able.


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## Phil Pascoe (29 May 2013)

Go to a motor factors and buy a bag of mixed springs - you'll find one that'll do the job.


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## Keith 66 (31 May 2013)

Whats the diameter & length & thickness of the wire? some years ago i needed four pressure springs for the feed rollers on a Multico planer, i used a couple of cut down old airgun mainsprings & they were just the job.


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## Baldhead (2 Jun 2013)

Thanks for the help guys, the picture is of a bench disc/belt sander, I was given one but the tensioning for the belt is missing, I asked if anyone could send me a picture so i knew how the belt is tensiones, this picture was sent to me by a fellow member, I will try some car accessories to see if they can help.

BH


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