Restringing a rotor: for dummies

[Hobart]

Alrighty so, a few days ago I ended up buying a Reynolds bass from DJ Kennedy, and it's a good horn.
However, I grew up with the luxury of mechanical linkages, and I'm trying to get the string linkage figured out.


Is this correct? I followed Yamaha's manual. It works most of the time, the problem is that it won't return fully back to the Bb position from time to time, it gets close but isn't all the way.
Do I need to loosen the string somewhere, or should I have the valve cleaned?

[BGuttman]

Can you manually push the lever back where it should rest? You may just have the loop on the actuator arm in the wrong location.

Loosen the small screw on the actuator part of the rotor (flat head) and move the string so that at the rest position of the lever the rotor arm is at the stop. Then tighten the string back down.

There is a good set of instructions on the Osmun Brass Web Site (you'll have to look it up). French Horn players need to fight with strings all the time and get really good at it.

[Hobart]

I can manually push the lever back to where it's supposed to rest, it gets all the way there 95% of the time, quieter than any mechanical linkage i've had, it's just that it sticks halfway sometimes.

[Elow]

I’m sure your local tech won’t charge for restring. The ones near me don’t and my shop doesn’t.

[Posaunus]

I’m sure your local tech won’t charge for restring. The ones near me don’t and my shop doesn’t.

Not true everywhere, unfortunately!

[Savio]

It looks ok. I think it's important what Bruce told, loosen that flat screw and pull the trigger a few times. Then tighten it. I had some trouble a while back because I didn't have the right string. Went to many sewing shops but none had the right string. Had to order it from a brass shop.
Leif

[Burgerbob]

Looks like it might be a bit loose. Also, typically the lever arm is a lot closer to the stop arm with string linkage. I wonder if it's bent away.

[flotrb]

Try this...be sure that the "over's" and "under's" are in the right directions:

[hornbuilder]

The lever arm is too far from the valve spindle. It really shouldn't be any further away than the thickness of the string. Have a tech adjust the lever, and then restring it.

[SteveFoote]

I think the fix is really simple. Looks like the lever is about 1/2 actuated and the valve itself is not actuated. Just loosen the string set screw and while holding it so it does not turn, and move the lever to a more not actuated position. Then tighten the set screw. Look at the diagram above. The set screw should end up about under the hole in the lever, or looking at it another way, there should be a longer length of string toward the bell end of the horn and less string toward the tuning slide end when the valve is not actuated. Yours is about in the middle. Doing this will put more tension on the spring and probably keep the string from rubbing against itself as the valve closes. It is a little hard to tell but it looks like the string is wrapped around the stop arm hub correctly. The string should not cross over itself as the valve moves. If it does the valve will be slow and the string will wear out very quickly.
Let us know how you get the issue corrected.

[Crazy4Tbone86]

The Essentials of restringing a rotor.....

*One of the best knots for rotor string is the quintuple half hitch. This knot actually gets wider the more you tug on it, so it will never slip through the hole even with excessive pressure.
*After starting with your knot, the string ALWAYS goes under any string that it passes.
*The lever position can be adjusted with the screw on the stop arm. However, the lever arm/lever position might need to be adjusted using duck bill pliers to create the proper axis of the the lever arm (see next item).
*For most efficient action, the axis of the lever arm should angled out slightly in resting position and angled in slightly in the engaged position. The lever arm should be perfectly perpendicular with the flat part of the valve casing when the valve is half-way engaged.
*The lever arm should be very close to the stop arm spindle but not actually touching it (also adjusted using duck bill pliers). Sometimes the string actually prevents the level from touching the stop are spindle.
*If the valve does not completely return to the resting position, the tension at the string set screw is too tight. Relax that part of the string the slightest bit so that the rotor can return completely to rest position (valve not engaged).
*There should be no "loss of motion" in a rotary valve action. In other words, if the lever is moving even 1/10th of an inch and the spindle is not rotating, something is too loose and needs to be adjusted.

If none of this makes sense.....take it to your technician!

[Vegastokc]

The timing of this thread (pun intended ) could not have been more perfect.
I ended up having to replace a string this weekend for only the second time in the life of the horn (or at least since I have had it).

[Crazy4Tbone86]

The old string rotor models get a bad rap (bad rep for the purists out there). Everyone assumes that the modern mechanical linkages are superior. I am not going to state which one is superior. However, I will tell you this......the action on a string linkage is more efficient. This is because the lever rod on a string linkage moves in one, straight direction. If you study the motion of every mechanical linkage, even on the best ones, there is some type of lateral motion in the action. In a mechanical linkage, the lateral motion is unavoidable because the stop arm must travel a small lateral amount to rotate the spindle.

There are a lot of pro horn (as in French Horn) players that went over to mechanical linkages (Mini-Ball, Uni-Ball, Ball and Nylon Socket, etc....) and then came back to the string linkages. The efficient action is the reason. That being said....a string rotor must be set up correctly to be effective. If a person says they "hate string rotors," they could have had one that was set up poorly.