Valve alignment question

[abracadabra]

Hello folks

I'm finally getting around to doing some work on this old Barcon mini sousaphone I picked up.

I don't usually work on valve instruments (clarinets, strings, trombones mostly) so this is new for me.

I aligned the valves per the Erick Brand method, in his book. I used the little gauge that I stuck down the valve casing, measured the cork/felt size for all the valves. I double checked #2 valve visually (the only one I could really see through a tuning slide)

Then I checked the downstroke on #2 visually and adjusted the other valves.

Now, #1 valve came out a little lower than the other two....shouldn't they be even? I checked and rechecked with the measuring tool. I can't see down the tuning slide to check visually. But the finger button on number one sits a bit lower than the others.

Unfortunately I can't do a real play test as I'm re soldering a new water key and the bell is unsoldered as well. That might tell me something.

Thanks for any help!

mark

[Dan Schultz]

Did you check to see if the piston stems are the same length?

[SousaSaver]

That method works but it isn't terribly reliable because the tools used to measure can slip or sometimes things just aren't built properly.

Your best bet would be to use a scope of some kind or some kind of dental mirror with a little LED light. Visual inspection is the best way to go if you can.

Believe it or not the valve stem lengths don't always line up when the valves are properly aligned. Many do, but some don't.

Just my opinions, I could be wrong...

[abracadabra]

Did you check to see if the piston stems are the same length?

Oh! I will go check this right now.

[abracadabra]

Well well, the 1st valve stem is in fact shorter than the other 2. Didn't even thing to check that!

thanks!

mark

[abracadabra]

Of course now it hits me that the downstroke for valve 1 is going to be off.

I just checked out #2 and then used the same felt thickness for the other valves, but course since the 1st valve stem is shorter, its not going to go down as far to begin with let alone with some felt in there. I wonder even with all the felt out of the cap it would be enough, its literally .105" shorter than the 2nd valve.

What can I do here?

mark

[pgym]

The only way to know is to try it.

If the shorter stem is original, the mfg likely took that into account when locating the ports body of the piston.

[Dan Schultz]

Of course now it hits me that the downstroke for valve 1 is going to be off.

I just checked out #2 and then used the same felt thickness for the other valves, but course since the 1st valve stem is shorter, its not going to go down as far to begin with let alone with some felt in there. I wonder even with all the felt out of the cap it would be enough, its literally .105" shorter than the 2nd valve.

What can I do here?

mark

If you can get the port alignment 'right' on the piston with the short stem... then you can just shorten the other two stems to match it. If not... add a spacer made from a piece of brass round stock under the button of the stem that is too short. Of course... this shim would have to be the same diameter (or maybe a bit smaller than the existing stem).

You never know what you have with a used horn. It could have been and out of several hands before it got to you. Often... stems are replaced willy-nilly by novices and as long as the results are acceptable... the horn goes back into service.