Trumpet DIY Repair Tips – Broken Waterkey spring

19th February 2014

Problem: Waterkey spring has broken!

This minor problem is easily repairable, all that is required is the correct parts, possibly a tool and some patience. It may not seem like a minor problem at the time, as the instrument will no longer be airtight and it will squeak and be wildly uncontrollable. Firstly identify the broken spring, and there can often be more than one. The water key will be flapping and have no tension to it.

What to do:

If you are in an emergency and cannot source a replacement spring, you can use an elastic band to temporarily tie the waterkey shut, but this should only be temporary as the rubber can eat away at lacquer and plating over time. Buying a spring should be very simple, as you can buy generic sizes or specific ones for particular brands. The fitting can be very fiddly, and the ideal tool is the spring installing jig (see here) Remove the water key, and place the new spring as shown, with the two legs facing forward.

Waterkey spring in jig

Mount the legs into the jig and draw them back as shown, this should feel very coiled and tensioned. Then, position the water key back in place and put in the screw, simple!

What not to do:

Do not attempt to glue the water key down, some glues can react with lacquer and plating and often need scraping off, resulting in permanent marks on your instrument. Sometimes a spring only has to break a little bit to lose its tension, but once it’s gone, it’s gone – do not attempt to bend or re-shape the spring to re-use it.