How do I make a simple, flat torsion spring? (in stainless?)

Muzzer, It is possible what he means is that they take a set (perhaps KWIL can confirm? ). Being involved in spring manufacture for automotive then you will undoubtedly been aware of the term "scragging" which refers to loading a spring element cyclically a number of times after manufacture to take away the initial set the end user would see otherwise.

Mark

I sympathise with the concern about the apparent cost of these springs, but this sounds very dodgy to me - do you have any parameters on these springs - under what conditions should they be able to work and so on? and to risk untested 'home-made' kit as part of the brakes on your car. Hope I don't live anywhere near this you. Bite the bullet and buy the correct parts, rather than take the risk.

Hugh Craig Harpsichords is a good fast supplier of music wire, all gauges.

http://stores.ebay.co.uk/hughcraigharpsichords/

Obviously you need to write in to Machinery's Handbook and complain that their extremely useful guides for mandrel sizes for winding compression and tension springs from piano wire have been misguiding engineers since 1914.

Alternatively you could buy a copy and learn how to wind some springs without heat treatment

There is a limit to the utility of some piano wire spring sizes but you should not be under the impression that winding soft and heat treating after is the only way to skin this cat, just because it's the only way familiar to you :D

I make some gun springs from Piano Wire because they work better and last longer than OEM springs so this is by no means a simple subject and there is no one right way to make a spring without testing, 

- Nick

Edited By Nick Hulme on 17/01/2017 19:02:59

I must admit, I thought this was the only way to make a proper spring and so a big thanks to all that contributed, I have made the springs, they are significantly better than the OEM ones which were more like cheap chinese paperclips.

An Other, perhaps you didn't read my original post describing the item and its purpose - and if you did, fair enough, I guess your one of those that has your brakes completely refurbished, because the garage told you they "needed doing" - I got told that once, and they had only just been done 3000 miles previously - but the worlds awash with fools silly enough to pay - I'd be surprised if some garages did even half the work they claim.

Beryllium-copper wire seems to be perfect for this job. Corrosion resistant, easily formed in the annealed state - you just need to soak it at 310C for 2 hours to develop the springiness which, sadly, is just too hot for a domestic oven but fine if you have one of these

Rod

Edited By Roderick Jenkins on 17/01/2017 20:52:17

Rod thanks, I'll keep that in mind going forwards.

I have an oven quite a bit larger than that in the lab at work, along with a small benchtop box furnace and some other useful heat treatment kit, they're frequently left on for significant amounts of time, just a case of waiting for something to come up at the same temperature.

I'm more "one of those who's been doing their own maintenance since their teens"

All the caliper systems I've dealt with with springs acting on the pads have had new springs included with an OEM spec pad set, so on the odd occasion where a spring has failed before a pad set change I've made one in the knowledge that it will go in the bin at the next pad set change,

- Nick

Edited By Nick Hulme on 18/01/2017 09:38:34