Replacing Valve Guides
I've read a book on how to replace valve keys. But I have neither clipping pliers nor a pillar file. So, I wanted to ask those of you who have done it before for your technique, and the tools you use.
I have a set of pistons that have been re-plated, and I want to change the keys (guides) and then lap them in.
The book talks about using clipping pliers to shape the key, which is a round head on a threaded base, trimming the head so it is slightly larger than the keyway, and then using the piller file to bring them down to size.
Reply #3 - Nov 14th, 2005,
I use a Dremel (in my case it was marketed as a fish scaler and sharpener) but the idea is the same.
I have a few different bits. one real rough that can remove a lot of brass - fast. The others gradually get down to a white one that you need to sit there for a while to get anywhere.
Remember to take the sides off equally - assuming it was correct in the first place.
Reply #4 - Nov 15th, 2005,
So, are you building the key entirely off the valve? Or are you finishing it up on the valve?
Reply #5 - Nov 15th, 2005,
Valve guides vary between manufacturers, but there are some main principles.
The guide is a short screw (inserted in the piston). It can be removed with parallel pliers, or flat pliers. It is important that the jaws of these do not have grooves or slots.
A new screw can most often be made from a brass screw that fits the tread. Here the manufacturers are different again, so what I tell you may not be possible with a specific instrument.
A suitable brass screw is mounted in the hole and tensed gently. The position up/down, as well as permittable height is marked on the screw's head, and it is removed again. A file can now do the work and reduce the screwhead to a slim notch that fits into the guide down in the valve housing.
Lapping is not necessary, just make sure that the new screwhead has no sharp edges that could cause damage to the groove down in the valve.
The width of the screwhead should make out no more than 9/10 of the width of the groove in the valve housing.
Reply #6 - Nov 15th, 2005,
OK, so you do all the fitting off the valve. The manual talks about cutting the screw head to where it is just slightly larger than the keyway and then putting it in the valve and doing the finish work on the valve.
Reply #7 - Nov 17th, 2005,
I mount the screw that will become the valve guide, and make the necessary markings on that screw, to make sure that the tread stops the screw head in the right position, and to make sure that the size will be OK. Then I remove it and work on it in a file clamp. If the file slips away, it will just scratch the file clamp, not the sensitive piston surface.
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Replacing Valve Guides Posts
Replacing Valve Guides
Apr 14th, 2006,
I thought I had this trumpet back together when I discovered a problem with the 2nd valve.
It would play fine for a while and then it would stick. Finally, I figured out that the guide was backwards. (i.e., the wide side of the guide, needs to align with the narrow keyway for the air to properly go through the valve.) But it won't go in the other way.
Now, it appears that the upper cage has been re-attached. And I'm not sure what these valves are made of. They almost appear to be billet aluminum.
I tried touching the solder with the torch, but they didn't come loose, so, I don't believe it is soft solder.
So, what recommendations would you have for fixing this problem.
Reply #1 - Apr 14th, 2006,
Take the floating guide out and make the necessary changes to IT so that it will fit in the cage the way it should. If the cage doesn't want to come off, don't try it anymore. If the guide isn’t modified, just find one that will. From the images you show, it looks like the one that's there is close to working either way, anyway.
Reply #2 - Apr 14th, 2006,
To modify the guide, to go in reverse, I'd have to narrow the wide side of the guide. I don't know if I want to do that. But I could drill the top hole in the cage a bit larger to get it to go in. That may be the way to go.
Reply #3 - Apr 15th, 2006,
Yes, I'd drill the top in a second. The guide (should) never go that far up in use, so it shouldn't matter.
Reply #4 - Apr 15th, 2006,
I'm also thinking about putting a drop of glue on the spring before setting it in the guide. That way it would hold the guild straight and be less likely to get thingy-eyed in the slot.
Reply #5 - Apr 16th, 2006,
Make as little changes to the cage as you can. Be sure there are no sharp edges pointing inward at the sides of the slot. They will remarkably reduce the spring lifetime.
The guide ought to have something that centers the spring, but it might be turned upside down too, so that the spring rest points downwards to the valve. If you work on the guide, try to screw the valve stem out of the cage, it should be able to. If it cannot, then instead try to fix the spring in upper position with a thin copper wire, so that you get both hands free for handling the guide.
Reply #6 - Apr 16th, 2006,
I guess because I'm a lower brass person, I've always preferred the simplicity of the bottom sprung valve.
But what is it about the top sprung valve that makes it popular? Is it supposed to have some advantage?
Reply #9 - Apr 17th, 2006
No valve guide traveling up and down with every depression of the valve.
-therefore-
no guide to stick, wear out, replace, and no casing wear.
no spring whacking the sealing surfaces.
(they've tried to minimize spring/port wear with conical springs, but guide/casing wear is still an issue; you can minimize it with plastic guides, but you must replace them more often. But everything is susceptible to cause a valve hang)
With a top-sprung valve, it’s all happening ABOVE the sealing surface, and out of the way.
(plus, I'm sure that the fact it's more complicated, has more parts to replace, and has more to market is not lost on the manufacturers)
Reply #10 - Apr 17th, 2006,
Valves with top springs do also come without the travelling valve guide in the cage.
My old master said that top spring valves would perform better compared to bottom sprung, as the top sprung valves are dragged back, giving a smoother run, while the bottom sprung are pushed back. No matter what, the valves are always pushed down, so why is that not a problem!?
If someone will make a big advantage of spring location, it is marketing stuff. The craftsmanship is more important.
The Marketing departments’ tribute to keyed instruments:
"The light action keys allow fast scales, keys will always be faster than valves, they require no valve oil, and never let you down in cold weather, like valves do. Keyed instruments are able of playing chromatic, having no 3rd valve offset problem that requires you to correct the tuning while playing! Make your next trumpet a valveless keyed trumpet from......!!"
Apr 14th, 2006,
I thought I had this trumpet back together when I discovered a problem with the 2nd valve.
It would play fine for a while and then it would stick. Finally, I figured out that the guide was backwards. (i.e., the wide side of the guide, needs to align with the narrow keyway for the air to properly go through the valve.) But it won't go in the other way.
Now, it appears that the upper cage has been re-attached. And I'm not sure what these valves are made of. They almost appear to be billet aluminum.
I tried touching the solder with the torch, but they didn't come loose, so, I don't believe it is soft solder.
So, what recommendations would you have for fixing this problem.
Reply #1 - Apr 14th, 2006,
Take the floating guide out and make the necessary changes to IT so that it will fit in the cage the way it should. If the cage doesn't want to come off, don't try it anymore. If the guide isn’t modified, just find one that will. From the images you show, it looks like the one that's there is close to working either way, anyway.
Reply #2 - Apr 14th, 2006,
To modify the guide, to go in reverse, I'd have to narrow the wide side of the guide. I don't know if I want to do that. But I could drill the top hole in the cage a bit larger to get it to go in. That may be the way to go.
Reply #3 - Apr 15th, 2006,
Yes, I'd drill the top in a second. The guide (should) never go that far up in use, so it shouldn't matter.
Reply #4 - Apr 15th, 2006,
I'm also thinking about putting a drop of glue on the spring before setting it in the guide. That way it would hold the guild straight and be less likely to get thingy-eyed in the slot.
Reply #5 - Apr 16th, 2006,
Make as little changes to the cage as you can. Be sure there are no sharp edges pointing inward at the sides of the slot. They will remarkably reduce the spring lifetime.
The guide ought to have something that centers the spring, but it might be turned upside down too, so that the spring rest points downwards to the valve. If you work on the guide, try to screw the valve stem out of the cage, it should be able to. If it cannot, then instead try to fix the spring in upper position with a thin copper wire, so that you get both hands free for handling the guide.
Reply #6 - Apr 16th, 2006,
I guess because I'm a lower brass person, I've always preferred the simplicity of the bottom sprung valve.
But what is it about the top sprung valve that makes it popular? Is it supposed to have some advantage?
Reply #9 - Apr 17th, 2006
No valve guide traveling up and down with every depression of the valve.
-therefore-
no guide to stick, wear out, replace, and no casing wear.
no spring whacking the sealing surfaces.
(they've tried to minimize spring/port wear with conical springs, but guide/casing wear is still an issue; you can minimize it with plastic guides, but you must replace them more often. But everything is susceptible to cause a valve hang)
With a top-sprung valve, it’s all happening ABOVE the sealing surface, and out of the way.
(plus, I'm sure that the fact it's more complicated, has more parts to replace, and has more to market is not lost on the manufacturers)
Reply #10 - Apr 17th, 2006,
Valves with top springs do also come without the travelling valve guide in the cage.
My old master said that top spring valves would perform better compared to bottom sprung, as the top sprung valves are dragged back, giving a smoother run, while the bottom sprung are pushed back. No matter what, the valves are always pushed down, so why is that not a problem!?
If someone will make a big advantage of spring location, it is marketing stuff. The craftsmanship is more important.
The Marketing departments’ tribute to keyed instruments:
"The light action keys allow fast scales, keys will always be faster than valves, they require no valve oil, and never let you down in cold weather, like valves do. Keyed instruments are able of playing chromatic, having no 3rd valve offset problem that requires you to correct the tuning while playing! Make your next trumpet a valveless keyed trumpet from......!!"