Replacing a broken clockspring

[MartyNeilan]

The clockspring on the 2nd valve on my Cerveny F tuba broke. This is one of the horns that has the individual screw tension adjustements on each valve. Where do I begin?

P.S. I am very happy with the current setup and do NOT want to convert.

[Chuck(G)]

I don't know if the adjustment mechanism makes this clockspring any different than the non-adjustable ones, but to replace the non-adjustable ones, you'll note that the little cassette is actually a 2-piece affair and is usually just held together by a friction-fit.

I separate the parts by placing the cassette on padded open jaws of my bench vise, then giving the axle a light tap with a rawhide mallet. Comes right apart--and will go back together with a little bit of pressure.

The clockspring's usually held in a slot in the axle and a similar slot in the outer body. You may still be able to order new springs, but if you can't, no big deal. I drop by the local antique clock shop and ask for old mainspring. They give me all I want for nothing, since they routinely replace old mainsprings in wall and table clocks.

Ends can be formed by using a pair of flat-jawed pliers as a heat sink and heating the part that needs to be bent to red heat in a torch flame.

Wear gloves when you wind the spring up, these things can really chew your fingers up.

[Mark]

I also agree with the gloves bit; thick, leather ones . . . slashie, ouchie!!

If you forget to wear gloves and the spring does chew up your fingers, will you ever be able to play the viola again?

[windshieldbug]

I thought those litle wheels had gerbils running in them!

[MartyNeilan]

Well I finally gave it to the pros and it got taken care of (correctly).
I had all four clocksprings replaced; the 5th and 6th valves used spiral springs. Harley's Bandroom in Nashville did the work and ordered the specific Cerveny springs from a supplier. Here is a pic of the original springs. Note that the other three springs are still in excellent shape despite being possibly three decades old. Brent, the repairman, said that it looked like somebody kept overtightening the adjustment screw until the spring snapped. My two-year-old likes to go over and play with the valves, she probably just kept turning tension knob one day.