- Messages
- 7,850
- Locality
- Near Lutterworth, Leics.
This thread follows on from this one: Saxophones - Conn 7M - G#/C# linkage "discovered"
I pulled the 7M out at last to have a look more closely at the removable linkage described in my previous thread, the one which supposedly makes C# feel a little mushy.
Removing this linkage, which I did for the first time today, makes little difference as it's the C# key alone which is the issue and not the extra burden of the G# key. I replaced it.
This short video shows the set up from touch piece to key cup...
View: https://youtu.be/ctxy5rjf9W8
I've observed the following:
1/ The C# actuating rod end in the fork near the C# key cup is very close to the fulcrum with little leverage on it. If it had been at the open end of the fork there would be far more leverage and control.
2/ Applying light pressure to the C# touch piece in the pinky table there is a tiny bit of movement in the rod end before the key cup starts moving.
3/ Once the key cup is fully open there is no mechanical "stop" to the key so my tendency is to keep pressing the C# touch piece until the attached G# foot (felted under) meets the body tube and I can press no more. This extra travel to the C# touch piece at the pinky table is 4mm. That's 4mm of extra stubborn movement which my finger tells me it should be pressing until it comes to a stop, whereas the key cup was fully open 4mm ago. As I continue to press after the key cup is open the long connecting rod deflects perhaps 1mm to take up the strain and then returns to normal once pressure is removed. This extra pressing of my finger against the springiness of the long brass rod is what I believe is causing 95% of the "mushy" feeling. And of course it's totally unnecessary to press it this far. It explains precisely the feeling through the touch piece.
4/ The fork and pin linkage is dirty with contaminenents and needs cleaning.
What's my best solution to these? Is there any other issue you can see?
I think...
1/ I can't change the mechanics.
2/ Remove the fork and insert a closer fitting cork surrounding the rod end. Too close fitting and it will bind. I think it's probably just right at present.
3/ I can't see where or how I could place a "stop" to the C# rod. But a mechanical stop would solve the problem as it would limit my ability to press past the maximum key cup opening. How could this be done? Or should I just learn that I don't have to press so hard to fully open the C# key? This may be the ultimate solution.
4/ Clean and re-lubricate. I usually use gear oil as @Stephen Howard recommends but is that best on a corked rod/fork arrangement?
Any other observations and suggestions please?
More photos under...
I pulled the 7M out at last to have a look more closely at the removable linkage described in my previous thread, the one which supposedly makes C# feel a little mushy.
Removing this linkage, which I did for the first time today, makes little difference as it's the C# key alone which is the issue and not the extra burden of the G# key. I replaced it.
This short video shows the set up from touch piece to key cup...
I've observed the following:
1/ The C# actuating rod end in the fork near the C# key cup is very close to the fulcrum with little leverage on it. If it had been at the open end of the fork there would be far more leverage and control.
2/ Applying light pressure to the C# touch piece in the pinky table there is a tiny bit of movement in the rod end before the key cup starts moving.
3/ Once the key cup is fully open there is no mechanical "stop" to the key so my tendency is to keep pressing the C# touch piece until the attached G# foot (felted under) meets the body tube and I can press no more. This extra travel to the C# touch piece at the pinky table is 4mm. That's 4mm of extra stubborn movement which my finger tells me it should be pressing until it comes to a stop, whereas the key cup was fully open 4mm ago. As I continue to press after the key cup is open the long connecting rod deflects perhaps 1mm to take up the strain and then returns to normal once pressure is removed. This extra pressing of my finger against the springiness of the long brass rod is what I believe is causing 95% of the "mushy" feeling. And of course it's totally unnecessary to press it this far. It explains precisely the feeling through the touch piece.
4/ The fork and pin linkage is dirty with contaminenents and needs cleaning.
What's my best solution to these? Is there any other issue you can see?
I think...
1/ I can't change the mechanics.
2/ Remove the fork and insert a closer fitting cork surrounding the rod end. Too close fitting and it will bind. I think it's probably just right at present.
3/ I can't see where or how I could place a "stop" to the C# rod. But a mechanical stop would solve the problem as it would limit my ability to press past the maximum key cup opening. How could this be done? Or should I just learn that I don't have to press so hard to fully open the C# key? This may be the ultimate solution.
4/ Clean and re-lubricate. I usually use gear oil as @Stephen Howard recommends but is that best on a corked rod/fork arrangement?
Any other observations and suggestions please?
More photos under...