Lengths of valve strokes

[Bill Bryant]

I remember that my old Claude Gordon Benge had a longer stroke than usual, and now I see that certain horns claim short stroke valves. Has anybody measured these differences and can tell us just how different they really are? Also, is this an issue to anybody?
_________________
"Johnny, that must be a terrible thing to live with day after day!"
"What do you mean, Mr. B?"
"I mean, to have all that music in you, and not be able to get any of it out!"

[Bill Bryant]

I just measured the stroke on my Bach 37 and on my old Getzen Eterna flugel. The Bach 37 appears to be about .625 (I'm eyeballing it with a dial caliper so it may be off quite a bit) and the Getzen is around .650.

For those of you unfamiliar with how to measure this, you pull out a piston and measure the distance from the bottom of a top port to the bottom of a bottom port, making sure you're using ports that line up with a hole that is used for both the up position and the down position, not the ports used to direct air into a crook.

I'm very curious to know just how short the valve stroke is on the Taylor, the Vintage One, and others that advertize a short stroke.
_________________
"Johnny, that must be a terrible thing to live with day after day!"
"What do you mean, Mr. B?"
"I mean, to have all that music in you, and not be able to get any of it out!"

[Tootsall]

Or just hold a ruler parallel to the valve and note the marking adjacent to a location on the valve button when the valve is "up" and when it is "down" and calculate the difference (no need to pull the valve from the casing). My Eclipse (bauerfine valves, same as Taylor and Destino?) measures 14.5 mm. My Schilke B1 is 15 mm. That is 0.570 and .590 inches respectively.

[LittleRusty]

Remove the bottom cap on your valve, use the depth gauge on your micrometer to measure the up and down distances.

My 1972 Bach Bb is .630 in, 16.mm
My 2003 Bach C is .640 in, 16.2 mm

[_Ford850]

.602" Conn Vintage One C
.643" Calicchio Bb
.597" Besson Meha .597"
.683" Getzen Renaissance Bb
.656" Getzen Severinsen
These should be fairly close.
_________________
Mark LaSavio
Calicchio R1S2
Duda modified F. Besson
Getzen Renaissance
Conn V One C
Getzen 3850S cornet

[Bill Bryant]

Any measuring system that looks at the actual travel could be thrown off by worn or oversized pads either on the up or down strokes.

Measuring the actual ports on a piston comes closer to letting you know about the actual design.

Of course, combining the two measurements would be a partial (and only partial) indicator of whether your valves were aligned. If the ports are, say, .600 apart and the measured throw is .650, there's no way the valves could be lining up on both positions.

(stuff for another thread)
_________________
"Johnny, that must be a terrible thing to live with day after day!"
"What do you mean, Mr. B?"
"I mean, to have all that music in you, and not be able to get any of it out!"

[LittleRusty]

Good point Bill. I took out a valve and measured the distance between the vertically aligned ports in the valve.

Theoretically this should result in the correct stroke length.

My Bb measures .626 this way, so the .004 difference could be my eye. (I could not use the step guage to check the valve ports, it doesn't fit)

The C is .655 measuring the valve ports and 6.40 measuring the stroke. Perhaps a valve alignment is in my C's future.

[Tootsall]

You are correct that dismantling and measuring the height difference from the valve ports will give the theoretical stroke. For "actual" stroke, you still need to have the valve fully assembled since "felt crush" IS part of the whole equation. This is where valves that use hard rubber or other, non-compressible pads, will maintain a consistent stroke for a much longer (if slightly noisier) length of time!

Great idea on measuring from the bottom of the valve, Rusty. I'll check the Eterna cornet tonight and see how it compares.