TromboneChat

I can usually figure this stuff out, but this one has me stumped. I replaced both the bearings, which were seized. I put very soft bumpers on it. After lubricating and putting it back together, it makes this horrible noise on the return stroke. Can't figure out why. Is the spindle just worn out, maybe? It seems to fit snugly into the bearing.

It is hard to tell, but is the link hitting the pipe on the return stroke? Does it only happen when you release the valve fast?

I have a Shires that makes a similar sound, it when I push it down to fast/hard…

mbtrombone wrote: ↑Fri Dec 29, 2023 8:34 pm It is hard to tell, but is the link hitting the pipe on the return stroke? Does it only happen when you release the valve fast?

I have a Shires that makes a similar sound, it when I push it down to fast/hard…

No, I don't think the linkage is hitting anything. If you hold the lever and let it return slowly, it doesn't make the noise.

Just as a test if you swap the bumpers or turn the one on return around 180 degrees does the sound still happen?

Is that a bit of grunge next to the lower bumper, or is the plate cracked?

It really looks like the mini ball linkage is hitting the F tube. Maybe put some paper against that tube and see if the sound changes.
Try and push the spindle arm against the bumper and see how much clearance is between the F tube and the mini ball linkage. It’s a little hard not seeing it in person
My Olsen valves are at a different angle

brassmedic wrote: ↑Fri Dec 29, 2023 8:42 pm

mbtrombone wrote: ↑Fri Dec 29, 2023 8:34 pm It is hard to tell, but is the link hitting the pipe on the return stroke? Does it only happen when you release the valve fast?

I have a Shires that makes a similar sound, it when I push it down to fast/hard…

No, I don't think the linkage is hitting anything. If you hold the lever and let it return slowly, it doesn't make the noise.

It bounces and hits the tube... watch the video at quarter speed. A harder bumper might be enough to stop the overshoot, or not

ithinknot wrote: ↑Fri Dec 29, 2023 9:38 pm

brassmedic wrote: ↑Fri Dec 29, 2023 8:42 pm
No, I don't think the linkage is hitting anything. If you hold the lever and let it return slowly, it doesn't make the noise.

It bounces and hits the tube... watch the video at quarter speed. A harder bumper might be enough to stop the overshoot, or not

I just watched it at quarter speed, too. Both heads of the linkage arm are hitting the tubes. Put a piece of paper around each tube and the clink sounds will change.

…. or use a dry-erase marker on the linkage parts to show contact (like layout dye).

Put some harder bumpers in there so it doesn't bounce, and also has a solid stop point.

hornbuilder wrote: ↑Sat Dec 30, 2023 8:21 am Put some harder bumpers in there so it doesn't bounce, and also has a solid stop point.

I think this is a good idea in any event. A few years ago I spent some time trying softer (silicone) bumpers on a couple of my instruments. But I went back to the harder rubber ones because the softer ones compressed more (duh!) and so resulted in more noise. It was just difficult to impossible to get them adjusted so they would provide the correct valve position on open/close and not compress so much that they wouldn't click/clank. The harder bumpers had "seemed" somewhat more noisy to me, but in fact (because of the results of compressibility) the softer ones ended up causing more (and more irritating) noise.

I will try some harder bumpers today.

I put on a piece of that really hard neoprene that Allied sells. Much better. And it's not bouncing anymore. Thanks, everyone.

Just saw this, it does lol like the lineage is hitting, as everyone already figured out -- why is the linkage so wide??

harrisonreed wrote: ↑Sat Dec 30, 2023 5:11 pm Just saw this, it does lol like the lineage is hitting, as everyone already figured out -- why is the linkage so wide??

I checked the Instrument Innovations website, and that's how big it is, and the attachment point is right at the point like that.

The stop arm is shaped like that because it allows the linkage to maintain a "straighter", more direct or linear plane of action. Notice in the video how the orientation/position of the linkage is basically the same in open and activated position.

hornbuilder wrote: ↑Sun Dec 31, 2023 12:52 pm The stop arm is shaped like that because it allows the linkage to maintain a "straighter", more direct or linear plane of action. Notice in the video how the orientation/position of the linkage is basically the same in open and activated position.

Huh? If you place a point a specific distance from a point of circular rotation, the resultant path will always be circular. That stop arm can be shaped like a pretzel, airplane, bass clef, literally anything, and it doesn't change that.

But it's 3-dimensional geometry involved, and the action may not take place in a single plane and may not be precisely circular (think conic sections). I've had to shim my valve control arms because of the -- let us say -- "less than optimal" design/implementation on my Chinese clone. Without the shims (very thin brass or plastic washers), the linkage can bind or at least make some noise. I'm getting around to replacing some of that and making everything coplanar, but the Rube Goldberg shim approach actually works pretty well and involves no labor.

This is what I get for reading before I had my coffee. I retract my previous statement, didn't catch that it was regarding the influence on the linkage.

Well, to be fair, I had had my coffee and am on my second cup.

Still, the linkage in this case, the piece that we're talking about anyways, only rotates in one plane -- it does not have to stay exactly as wide as the screw / bearing it is attached to for it to do that job. Narrowing it or putting in a curved cutout to account for the diameter of the F tube would not change how it moves on that plane.

That linkage, by design, doesn't allow for compression of the bumpers.

LIBrassCo wrote: ↑Mon Jan 01, 2024 7:15 am

hornbuilder wrote: ↑Sun Dec 31, 2023 12:52 pm The stop arm is shaped like that because it allows the linkage to maintain a "straighter", more direct or linear plane of action. Notice in the video how the orientation/position of the linkage is basically the same in open and activated position.

Huh? If you place a point a specific distance from a point of circular rotation, the resultant path will always be circular. That stop arm can be shaped like a pretzel, airplane, bass clef, literally anything, and it doesn't change that.

Resisting the urge to have a pretzel-shaped linkage made.

Matt K wrote: ↑Mon Jan 01, 2024 10:10 am

LIBrassCo wrote: ↑Mon Jan 01, 2024 7:15 am

Huh? If you place a point a specific distance from a point of circular rotation, the resultant path will always be circular. That stop arm can be shaped like a pretzel, airplane, bass clef, literally anything, and it doesn't change that.

Resisting the urge to have a pretzel-shaped linkage made.

Matt don't joke, I'll totally do it

brassmedic wrote: ↑Fri Dec 29, 2023 8:15 pm I can usually figure this stuff out, but this one has me stumped. I replaced both the bearings, which were seized. I put very soft bumpers on it. After lubricating and putting it back together, it makes this horrible noise on the return stroke. Can't figure out why. Is the spindle just worn out, maybe? It seems to fit snugly into the bearing.

This noise is from bumpers. As Mr. Walker said.

No. The noise was from the ball joint hitting the tube. The soft bumpers were the reason why the ball joint was able to hit the tube, as they compress and allow the rotor to go beyond correct alignment, then bounce back a few times. The harder bumpers reduce bounce, and also ensure better alignment.

There is a way we measure the hardness of rubber (or other elastomers) called "Durometer". There are two scales for measuring: Shore A and Shore D.
Most rubber we would want to use is measured in Shore A. Shore D is for materials that don't compress easily like plastics (polyethylene, for example)
A very soft rubber might be 50 durometer, a medium rubber 70 durometer, and a hard rubber 90 durometer. Harder rubbers don't compress as much so the return spring may cause a slap. This is what we want to avoid with replacement bumpers. I'd bet a medium durometer rubber (or urethane) like a 70 would be soft enough to absorb the shock of the return spring but not so soft as to compress enough to let the stop arm actually hit the tubing.

Yes. I have a selection of material covering several durometer (what is the plural of durometer??) And use different hardness materials based on the particular application.

The soft silicone I use is 50A. Something I didn't consider is the Infinity valve has a very low profile - you have to cut the bumpers very thin in order for the stop arm to pass over them. Thinking about it now, that means there's less material and they will compress even more than normal. So I don't doubt the stop arm could have been hitting the tube, although if it was it was happening too fast to actually see it. It is not hitting the tube on the upstroke, though - if it looks like it is, it's a false perspective due to the angle at which I filmed it.