"Lost Motion"

jbtsax · Mar 20, 2018

"Lost Motion" is when a key moves but doesn't immediately contact another key that it is supposed to move. I'm sure British techs have their own names for this, but I can't remember what they are.

There are places on a saxophone where a bit of "lost motion" is ok---even desirable. This is done as a precaution so that the keys do not make contact and inadvertently hold another key open when it should be closed

Between the octave post and the ring of the neck octave key
Between the tabs extending from the G# touch going under the low B and C# touch
Between the front F mechanism and the palm F key

Places to watch for "lost motion" that is undesirable. This is not as cut and dried as one might think. A saxophone will play ok with some "lost motion" in the keywork, but it lacks a professional feel. The keywork is not as efficient when there is "lost motion" present compared to when it has been completely removed.

Where the B key closes the small C key above it.
Where the A key closes the small C key above the B
Between the A key and the Bis key below it
Between the low Bb touch and the tab from the low B touch
Between the G#/Bis adjusting screw and the lever from the Bis
Between the F and backbar of the F#
Between the E and backbar of the F#
Between the D and the backbar of the F#

Please add any areas that I may have overlooked.

Ne0Wolf7 · Mar 21, 2018

How about not wanting lost motion on the octave mechanism? I notice especaily on the older saxes from school that have had their octave arms (don't know what its actually called) bent down so its covers the little ocatave hole (also don't know what its actually called) have the big moving piece (you know the drill now...) not be very close to the vertical bar that pushes it feel mushy.

jbtsax · Mar 21, 2018

I think I know what you mean. That area needs about 1/16" of space so that the neck octave key doesn't accidentally open. More than that is too much IMO.

DartmoorHedgehog · Mar 21, 2018

jbtsax said:
"Lost Motion" is when a key moves but doesn't immediately contact another key that it is supposed to move. I'm sure British techs have their own names for this, but I can't remember what they are.
.

I've heard it called "double action" I think - not sure if that's a particularly British/American difference or just two terms for the same thing.

Colin the Bear · Mar 21, 2018

On a lathe or a chain drive bike it's called backlash. I don't know if that's appropriate here.

saxyjt · Mar 21, 2018

Excellent topic @jbtsax !

For a wannabe repairman like me, it's gold! So far, I've mostly dealt with issues as I encountered them. But I'd like to get to a point where I anticipate them.

I'm sure it'll take time, but I'ts worth it.

saxyjt · Mar 21, 2018

Oh, and for what it's worth, we call it 'jeu' (play) in French.

That's the allowance for movement between parts that are linked. Can apply to axles (both lateral and axial), hearing, you name it...

Any moving parts has some, otherwise they won't move! 😱

DartmoorHedgehog · Mar 22, 2018

Yes, "play" and "backlash" are both used as general terms for mechanical "slack" in (UK) English. When I mentioned "double action" I've only ever heard that applied specifically to keyed wind instruments, when there is excessive free movement of the key before all the connected parts of the mechanism start to move.

jbtsax · Mar 22, 2018

It is interesting how the British and Americans have different terms for the same things related to saxophones. A few I am aware of are:

Neck - Crook
Post - Pillar
Spring Cradle - Nipple
Lost Motion - Double Action

Even two different pronunciations for the same word:

Saxo-PHON-ist--------Sax-OPH-onist "Two different countries separated by a common language." George Bernard Shaw

Dibbs · Mar 22, 2018

I'm British and I've only ever heard it called lost motion*. As far as I know, backlash is a special case of lost motion that occurs when a drive changes direction, like in a gear train or leadscrew. A kind of hysteresis I suppose.

*Actually that's not true. Also slack and slop but they are more informal terms.

Pete Thomas · Mar 24, 2018

The crucial thing about the octave is that it's feasible to adjust it "perfectly so there is no play whatsoever, or at least no play you can actually feel. The problem then is that you might then put the neck on at just a very slightly different angle either left or right, and as there is no free play the neck ovtave key ring at a different angle is then forces the key open slightly. That can cause the the slightest leak. Also if there is no "give" then the slightest bending of the neck octave key ring.

Colin the Bear · Mar 24, 2018

And then there's the lost motion, on purpose, to mediate fudging squeaks. I was asked to have a look at a clarinet that had been in the shop a couple of times and still wouldn't play. I was quite bemused, for a time, by all the trill keys being locked shut. It turned out that there was nothing wrong with the clarinet but it needed adapting for unusually shaped fingers. A towel will help with a sloppy action. :rolleyes:

saxyjt · Mar 24, 2018

Colin the Bear said:
A towel will help with a sloppy action.

How so? Wiping the sweat resulting from a hard labour?

jbtsax · Mar 25, 2018

Pete Thomas said:
The crucial thing about the octave is that it's feasible to adjust it "perfectly so there is no play whatsoever, or at least no play you can actually feel. The problem then is that you might then put the neck on at just a very slightly different angle either left or right, and as there is no free play the neck ovtave key ring at a different angle is then forces the key open slightly. That can cause the the slightest leak. Also if there is no "give" then the slightest bending of the neck octave key ring.

Exactly. Another issue I have come across is the cork under the thumb key or under the arm that connects to the octave mechanism can compress when the player presses the thumb key a bit harder, this in turn causes the key to travel a bit farther opening the neck octave when playing G.

Stephen Howard · Mar 25, 2018

I've always called it double-action.

Another spot where it's sometimes beneficial is on the side C/Bb keys.
Much depends on the design of the keys and/or the linkages. If the Bb/C key cups are sprung and the levers aren't, some double=action is advisable to accomodate any settling of the pad over time.
On fork and pin connectors some double-action may be required to accomodate the changing angle of the pin in relation to the fork when the key is operated - else the action can feel slightly slow and stiff.

As for play - which usually describes wear in the action - some may be desirable in the octave key mechanism in certain circumstances. In the main this relates to cheaper horns, where less-than-precise build quality means that such mechs tend to bind or slow down if the mech is unable to move (very slightly) back and forth along its pivot. It's especially noticeable on cheap baritones.

jbtsax · Mar 25, 2018

Stephen Howard said:
I've always called it double-action.

Maybe that's where I heard that term.

Stephen Howard said:
Another spot where it's sometimes beneficial is on the side C/Bb keys.
Much depends on the design of the keys and/or the linkages. If the Bb/C key cups are sprung and the levers aren't, some double=action is advisable to accomodate any settling of the pad over time.

Good idea, I've see that design on some vintage saxes.

Stephen Howard said:
On fork and pin connectors some double-action may be required to accomodate the changing angle of the pin in relation to the fork when the key is operated - else the action can feel slightly slow and stiff.

Interesting. I am a fanatic about key noise---expecially on side keys. What often works for me is to polish the inside of the "fork" and to use teflon on the pin. I make the action quiet by closing the "fork" to be as tight as possible and still allow free movement of the key. The teflon tubing on the pin seems to allow a bit tighter fit than other materials, Sometimes it helps to tilt the fork slightly to get the best compromise between quiet action and free movement.

Stephen Howard said:
As for play - which usually describes wear in the action - some may be desirable in the octave key mechanism in certain circumstances. In the main this relates to cheaper horns, where less-than-precise build quality means that such mechs tend to bind or slow down if the mech is unable to move (very slightly) back and forth along its pivot. It's especially noticeable on cheap baritones.

I just got back from a clinic where Curt Altarac (Music Medic) described an octave key rocking mechanism with teflon balls on each end that fit inside an adjustable ring.

Colin the Bear · Mar 25, 2018

Teflon balls with an adjustable ring? So tempting >:)

saxyjt · Mar 25, 2018

Stephen Howard said:
As for play - which usually describes wear in the action

Shouldn't that be called 'foul play'... :rofl:

Here is what I found, looking at the English version of 'jeu'. FWIW.

Stephen Howard · Mar 25, 2018

jbtsax said:
Interesting. I am a fanatic about key noise---expecially on side keys. What often works for me is to polish the inside of the "fork" and to use teflon on the pin. I make the action quiet by closing the "fork" to be as tight as possible and still allow free movement of the key. The teflon tubing on the pin seems to allow a bit tighter fit than other materials, Sometimes it helps to tilt the fork slightly to get the best compromise between quiet action and free movement.

Another trick is to put a slight curve on the inner faces of the forks, but this isn't always practicable (or possible).

I just got back from a clinic where Curt Altarac (Music Medic) described an octave key rocking mechanism with teflon balls on each end that fit inside an adjustable ring.

Sounds very posh!