Thread: making springs

I have just finished making a small spring as part of the water key on a trombone. I found that it was very difficult to get the exact shape I needed. I bent the metal so often that I thought it would snap. Is there a proper way to shape a spring, using heat, maybe?

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Hi woolyhead
Many of us ,including yours truly will have scant knowledge of trombone water springs.
It might be real handy for those members who might be able to assist if you provide more details.

What brand model ,size is the trombone. Why did you have to make the spring? Are there no spare parts available for your model?

I know there are some as I googled the water spring term and found Thief Bay had some.

What tools are you using to work and hold the spring?

There are some jewelry tools that could be suited to hold and bend wire. Such small section springs .

I think springs would be made by an automated machine process and I would avoid the heat as you may easily lose the temper in a thin section as these springs appear to be, from ebay pics.


Please! Give as many details as you are able.

Grahame

You could go either way, if you heat it to make it soft, you will then need to re harden it after you form it, a small spring such as that would normally be made in a hardened state by machine probably
thousands at a time. Making a one off you need to create a small jig that you would give enough mechanical advantage to bend it in one smooth operation as you have discovered constantly re bending will lead to breakage
Some thing like this could be used with a bit of fiddling and some pliers https://www.youtube.com/watch?v=g8O1PuvteG0

For a small spring such as you are making I would be bending it cold. There are any number of youtube videos on spring winding/making, this is one of the many.

https://www.youtube.com/watch?v=jAawhg6JtyY

From Amazon or other sources you can buy 1 lb coils (lifetime supply) of spring wire of the diameter you want. Having an endless supply of wire enables you to throw away the failures rather than try to rework them.

Spring wire and music wire is supplied as already springy ie not soft, and is bent/formed cold - once wound/formed into a spring it should be heat treated to I think around 450C, this I believe makes it more resistant to taking a set, if it is not heat treated it may still work ok in the application but may take a set if over extended. The local spring manufacturer I sourced some spring wire from told me that spring wire and music wire are much the same thing with music wire being a slightly better (more expensive) grade, all of their springs are bent cold and then heat treated.

Originally Posted by Grahame Collins

Hi woolyhead
Many of us ,including yours truly will have scant knowledge of trombone water springs.
It might be real handy for those members who might be able to assist if you provide more details.

What brand model ,size is the trombone. Why did you have to make the spring? Are there no spare parts available for your model?

I know there are some as I googled the water spring term and found Thief Bay had some.

What tools are you using to work and hold the spring?

There are some jewelry tools that could be suited to hold and bend wire. Such small section springs .

I think springs would be made by an automated machine process and I would avoid the heat as you may easily lose the temper in a thin section as these springs appear to be, from ebay pics.


Please! Give as many details as you are able.

Grahame

Hi Grahame. It is difficult to find a suitable spring for my trombone because it is about 140 years old and they are not made like this one any more. I have already shown a sketch of the spring form on this forum under the heading Removing Dents From Brass, or something like that. I think that part of my problem is that the water key is worn out and again they don't make water keys to this shape now. It sits on the very end of the slider tubes whereas on a modern instrument it has been relocated to the side more, to avoid it being knocked. As a result the water key is bent round to suit whereas my one is not. I have repaired the key as well as I can but the epoxy resin used for this is bulky and takes up room where the springs need to go. I considered soldering the bearing tube to the key instead of using epoxy but the cap on the end of the key is also soft soldered and I was afraid it might fall off. I know about using a water soaked rag as a heatsink but this job seemed more difficult to me than epoxy repairing. I also used a hard plastic tube with a 2.4mm dia hole and 4mm OD and 9mm long to replace what I assume is the missing brass tube. At the time I didn't know that all modern water keys use a tube like this to reduce the wobble of the key by increasing the length of the key's bearing on the 2.3mm dia pin. You might think that I could have bought a replacement water key but as explained all new type keys are bent and not straight. The piano wire used with new springs measures 0.9mm diameter and is quite stiff. So I used epoxy on the existing key and made a water key spring using fine nose pliers and a wooden dowell and some 0.5mm piano wire so as to get it into the space left by the epoxy repair. I got there eventually but it did occur to me that there might be better ways to make springs so I asked this forum.