Source For Spring Wire

[Discord]

I was lucky enough to have a jewellers, wire draw plate thrown in with a load of old watchmakers tools, bought about twenty years ago.

Never had a use for it until I needed to replace a concertina spring recently. They sell draw plates quite cheap on ebay these days.

Got some soft brass wire off ebay and drew it through the reducing holes until it was the same diameter as the corroded original springs.

The process of drawing down the wire to the correct thickness hardens the wire. Works perfectly.

If you don't want to buy a draw plate for a couple of springs ask around and find a friendly ( I think I mean cheap working) amateur or proffesional jewellery maker, they should help. They will probably have the brass wire in their bits and bobs box.

Cheers.

[ttonon]

This is a very interesting thread giving the preferences that makers/repairers have in choosing materials to make concertina springs. But apart from price and availability, I didn’t see many technical reasons given for these preferences. Perhaps the technical reasons are pretty well understood by this community and not worth mentioning? But I would be very interested in these. Would someone please care to elaborate?

 

Best regards,

Tom

[Don Taylor]

Tom

 

I started this thread because I want to lighten the action on my Peacock and found it really difficult to adjust the stainless steel springs.

 

It takes a lot of force to get them past their elastic limit and it is very easy to overdo it and then have to try to partially revert them.

[Discord]

Hello Tom

I hope I have understood your comment correctly.

My technical reasons are as follows.

 

The springs that are in my English Wheatstone are brass and the helpful chap at Wheatstone in the UK still supplies brass springs to this day.

My brass springs could be the originals of around one hundred years of age.

To replace a couple of springs with spares from Wheatstone would not be very expensive but I have my eye on a wreck that I fancy renovating completely, so making 48 springs of my own seems the cheapest option.

A lot of brass wire on the market today is sold in a soft or semi hard state. When you bend it , it stays bent and has no spring in it, just like a wire paper clip.

Wire that has been already hardened is very difficult to find in the UK, a lot of basic industries have vanished, closed and the machines sold off to places like India.

The machines are reassembled and the goods from them sold back to the UK. It happened with our cotton mill looms, car parts manufacturers and even the tiny local factory making engineers files closed in Prescot , Lancashire and sold its machines to India. I think that was in the 1980s. Prescot was once world famous for watch and clock making and file and tool making, and even wire making. All long gone.

As I said in my earlier post, the action of thinning the wire by drawing it through smaller and smaller holes in the draw plate actually hardens the wire into spring wire.

Wire that can be bent but will spring back.

 

Basically my technical reasons are not very technical.

I needed hard brass wire. That was the original spring material in my instrument.

The amount of springs required for my planned project would be expensive, and it would be satisfying to say " I made every spring in that concertina"

I couldn't find hard brass wire.

I had the tools and the knowledge to know about drawing wire from my clock making activities.

Lastly, I love making and repairing things.

 

Cheers.

[ttonon]

It takes a lot of force to get them past their elastic limit and it is very easy to overdo it and then have to try to partially revert them.

 

Hi Don, I have found similar behavior. I’m not sure I saw it in the thread, but I sometimes use guitar string to make springs, and there are other musical instruments that use different materials for their wires (dulcimer, zither, and others). You might give it a try if you haven’t so far.

 

In the worst case, I found it necessary to take out most the springiness in steel spring wire, though it should work for any heat treated spring metal. To do this, I made an annealing apparatus that would very evenly heat the wire along its length for a specific time and heating current. On a plywood mounting board, I screwed in an anchor to which one end of the wire is attached about 3/4 inch above the board. I screwed in another anchor at a convenient distance away, depending on what length wire I wanted to anneal. I used an anchor here with a round cross section, then doubled back the wire to an ending anchor at its beginning location, providing two lengths of wire. If you want more lengths, simply move in a zig-zag way across the board. The two end anchors had electrical connectors, to which I attached the outlet of a Variac (also called autotransformer), which you plug into your AC wall outlet, and the AC outlet voltage of the Variac goes from zero to 100 % of outlet voltage (some makes provide 140%), depending on the position of the dial on the top of the instrument. These devices are usually fixed with 10 amp fuses (for 115VAC input). For me, I wanted to take out most the springiness, and with a little practice, I selected a convenient Variac dial setting and counted out the right amount of seconds. (For a more sophisticated apparatus, you could add an ammeter and a timing plug to accurately control these parameters.) The wire got to a dull red, better visible when room lights were switched off, and it took about 4 – 5 seconds. My guess for you, a similar red color for perhaps only one second. For a given cross section (gauge) the same current will produce the same anneal temperature (neglecting heat losses), and the anneal time will depend only on the anneal temperature. At the end, it’s best to bring down the wire temperature gradually, to prevent hardening, although this would apply only to high annealing temperatures and certain heat treating alloys.

 

Basically my technical reasons are not very technical. I needed hard brass wire. That was the original spring material in my instrument. The amount of springs required for my planned project would be expensive, and it would be satisfying to say " I made every spring in that concertina" I couldn't find hard brass wire. I had the tools and the knowledge to know about drawing wire from my clock making activities. Lastly, I love making and repairing things.

 

Hi Discord, It seems to me you require a technical feature of “workability,” but the fact that makers have been using full-hard tempered brass that lasts for a hundred years certainly points to its advisability.

 

If you’re serious about pursuing the use of brass for your springs, it may be helpful to understand some of the basics. I agree that the method for making hard brass is by mechanical deformation, and for springs, the degree of hardness is one important property, most commonly described as zero hard (annealed), half hard, and full hard. From your description, you are probably in need of full hard brass. But also important for springs is the alloy composition of the brass, which is part of the full designation of the spring material. Concerning material properties on a more basic level, the yield modulus is the property of interest for springs. A spring needs to withstand high stresses and not bend, and this is what this property measures. Although Young’s modulus describes the spring constant of the intrinsic material, it doesn’t change much with different degrees of hardness for a given alloy, but the yield modulus – as you’d expect – does undergo significant change.

 

I suggest you go to matweb.com, a premier site for property values of all kinds of materials. A page there that describes “spring brass” is: http://matweb.com/search/QuickText.aspx?SearchText=spring%20brass. On these pages, springiness is described as “spring” or “extra spring,” probably correlating with the more common terms, half hard and full hard. Clicking on the names of these alloys brings you to a page that describes their uses (at the top), and property values. If one of the uses is for springs, it will say so, and from that info, you can see that the corresponding yield modulus needs to be a little above 100,000 psi for extra spring quality. Minimum useful values appear to be below 80,000 psi.

 

I find that there are still several companies in the US that make what they call spring brass, and a web search works well. You can correspond with these companies on what they really mean by “spring brass” and if they make it in the diameters you will need. They may recommend procedures for buying what you need (through the company, or distributors). My guess is that small hand held spools with different diameter wire shouldn’t be too expensive, if you can find them, without large minimum orders. Once you know exactly what you need, you can also go to Ebay, Amazon, banggood, and other web outlets. Good luck, and I’d be curious to know what you find.

 

Regards,

Tom

[Chris Ghent]

Recent arrival from the US, around $25 per 1/4lb spool. The manufacturer is malinco.com/industrial-wire.html

 

[ttonon]

Hi Chris, interesting that the material is phosphor bronze. Is this the traditional material going back a hundred years or so?

 

Regards,

Tom

[Chris Ghent]

Tom, the short answer is, while I suspect not, I don't know. My recollection is a pb spring will bend many many more times before it breaks compared with brass. But all of my understanding on this topic is received from Dana who really understands so many materials and machining things and I anticipate he will see your query and respond to it before long.

[Dana Johnson]

Speak of the devil.

There are few things spring tempered brass ( by work hardening ) is better for than spring tempered phosphor bronze. Brass has been around a lot longer, so has a history in things like concertinas. P Bronze as Chris says, is more durable ( and corrosion resistant ) in any spring application than brass alloys. It is very close in its spring properties to brass spring wire and is useable in similar gages as well as being widely available. Keep in mind that commonly available brass wire is not an ideal spring alloy which requires a more elastic formulation like cartridge brass. Concertina springs are hardly a critical application though and a lot of different things will work.

Concertina springs ( the traditional sort ) are designed to increase in tension very slowly when pressure is applied. This keeps the button feel constant in it's travel. All concertina springs require a bit of pre load so they are under close to full tension when the button is in its up position. Trying to reduce the tension by reducing the pre load works to a degree as long as you are still applying enough preload to keep the pad pressure sufficient. If you are getting anywhere close to that line though, the spring is improperly designed. If you want a lighter spring, there are three things you can do. First is to use a lighter gage of wire, second is to add a coil, and third is to increase the coil diameter. Long ago, I was designing my springs and found the typical coil diameter for traditional springs caused them to fail after a few hundred thousand cycles. I switched to winding my springs around a .125 inch mandrel and stopped counting after 4 million cycles. The springs were still fine. The larger coils did not have the compression fractures on the inside of the coil that the small coils created. This is a proportional thing though, so smaller wire can take a sharper bend.

When you are thinking of adding coils or increasing the coil diameter, you are just spreading the deflection over a longer piece of metal. You can think of a concertina spring like a long diving board with most of the length coiled up. Adding coils or increasing the diameter just makes it longer ( and easier to flex over the same distance ). More coils creates a more even feel, heavier wire does the opposite other factors remaining the same. Too fine a wire requires you to reduce the coil number, creating less ideal stacking of force, and higher stress on the wire or use a lot of preload to get enough tension. I find that 3 coils is a good number for my wire, but use 2 for the air button which also uses a gage thicker wire for the extra tension the large air pad needs. Since I feather the air valve all the time, I need it not to be super easy to open all the way, so as long as it doesn't hurt my thumb, I like the extra tension.

I like to use stainless steel spring wire which is more easily formable than music wire steel and corrosion resistant in the bargain. If you are going to use brass or P Bronze, try adding one coil or increasing the coil diameter to reduce the tension but keep the initial preload enough so you don't risk a drop off Shen the button is at the top of its travel. Springs can have a nearly infinite life span in terms of cycles if the stress is kept below a certain level. Above that and their life can drop off quickly.

Dana