What's it for? - Page 2

Vulgano Brother · 11-17-2007, 07:42 PM

The screw holds the valve guide onto the valve. Some valve guides are split, allowing them to be splayed over time for a better fit, or one can unscrew the old guide and put a new one in. Good luck finding replacement guides, though. A fun book to have is the Eric Brand Repair Manual, which shows how to do all kinds of fun stuff, and repair/ruin an instrument by ourselves.

crowmadic · 11-18-2007, 08:45 AM

Brekelefuw, Do you know what the screw is for?

confuoco · 11-18-2007, 09:29 AM

Got any pictures of what you are describing?

oldlou · 11-18-2007, 03:25 PM

Quote:

Originally Posted by Brekelefuw

Lapping is taking material away from the valve casing or valve, so be really careful and make sure there isn't another fix. If the valve slides ar damaged it could be as simple as bending them back to their original place so the valve casing straightens out.

This is often the case with the second valve slide tubing. It is easily bent by impact or a too tight case, or some fool kid cramming music charts or books into a case that was made to be a nice comfortable fit for the horn. In 'most' cases, this results in the solder joint connecting the tubing to the casing is slightly stretched, allowing the tubing to very slightly impinge into the casing interior. Most techies can cure the problem in about 30 seconds.

OLDLOU>>

crowmadic · 11-19-2007, 08:25 AM

It came to me in a dream last night. The screw I'm talking about does keep the valve guide in the track of the valve stem as Vulgano Brother mentioned. It also fits into the slot inside the casing that stops the valve from spinning. Could that screw also be influential in angling the valve, and thereby be a source of correction for valves that drag when all other potential causes are elliminated?.........crow

oldlou · 11-19-2007, 11:25 AM

Quote:

Originally Posted by crowmadic

It came to me in a dream last night. The screw I'm talking about does keep the valve guide in the track of the valve stem as Vulgano Brother mentioned. It also fits into the slot inside the casing that stops the valve from spinning. Could that screw also be influential in angling the valve, and thereby be a source of correction for valves that drag when all other potential causes are elliminated?.........crow

If the guide key is the original in that piston it is highly doubtful that the guide key would be in any way contributory to the piston being pushed to one side in the casing. It might be worn to the point that it no longer perfectly lines the passages in the valve piston with the holes for the loops.

The screw only holds the guide key firmly into its machined slot. This is one of those screws that should not be messed with, except by a technician in the process of replacing a worn guide key.

OLDLOU>>

oldlou · 11-19-2007, 11:38 AM

Quote:

Originally Posted by MFfan

After more email talk with Lou, I took photos of the valve piston in question and sent them to him, first, on his suggestion, pulling the valve out straight and try to determine if any observable wear could be lined up with the interior 1st valve tubing, which might indicate some abnormality there that could hang up the piston. I couldn't definitively connect anything there. He reviewe the photos and noted the bottom of the piston was "galled" It does have a scraping pattern around the bottom sides of the piston all around extending a very short distance upwards. One of his other ideas was that the valve casing could have been slightly damaged and causing a hang up, but I don't see any.
Anyway he wants to see it personally and compare it with the pristine valve of his Collegiate cornet. Turns out mine is bottum sprung and his is top sprung. We are meeting Monday at a location equi-distant and will go from there. There is some wear patterns of different sorts on the piston, but I don't know what they indicate. Will report further. There is no problem with the other valves on the horn. I will ask him about the screw. Maybe he will see this post and respond. Dave

I just now got back from meeting Dave at The Big Boy Restaurant in Wayland,Mi., about midpoint between his home in Kalamazoo and mine in Grand Rapids. I inspected the subject valve and discovered that it had been dropped at some time prior to his ownership, slightly collapsing the bottom skirt of the piston. This caused the new dent to swell out the skirt very slightly on either side of the dent, thus impinging upon the casing wall. I dressed the high spots on the skirt with a fine cut jewelers file and the valve now runs free in the casing. I told him to acquire some ultra fine 1500-2500 auto body wet or dry sanding paper and to finish the work by polishing the file marks away, just on the edge of the skirt making it very slightly conical at that very bottom edge. The problem is solved without removing any material from the sealing portion of the piston or casing.

I forgot to instruct Dave to clean the piston VERY completely before reinserting the piston into the casing, to make certain that there is no remaining abrasives or metal sandings to rapidly wear the piston and casing. I hope that you read this, Dave.

OLDLOU>>

MFfan · 11-19-2007, 09:41 PM

Quote:

Originally Posted by crowmadic

that's the right thing to do MFfan.........crow

I met with Lou today. He could see immediately that the bottom edge of the piston was somewhat damaged and though someone must have dropped the piston at some time. He had some jewelers' files with him and filed down the edge of the base down so it works nearly perfectly and rarely gets hung up. I am supposed to get some 1500-2500 wet dry sandpaper as used by body shop to smooth off the filed area, being careful not to touch the piston sides. I played the horn a lot tonite in the swing band I play in and didn't have much trouble. Dave

11-17-2007, 07:42 PM	#11 (permalink)
Vulgano Brother Moderator Fortissimo User Join Date: Mar 2006 Location: Home Posts: 3,232	Re: What's it for? The screw holds the valve guide onto the valve. Some valve guides are split, allowing them to be splayed over time for a better fit, or one can unscrew the old guide and put a new one in. Good luck finding replacement guides, though. A fun book to have is the Eric Brand Repair Manual, which shows how to do all kinds of fun stuff, and repair/ruin an instrument by ourselves. __________________ "A tool good enough to be so used and not too good" C.S. Lewis That Hideous Strength www.letsbuildhope.org

11-18-2007, 08:45 AM	#12 (permalink)
crowmadic Mezzo Piano User Join Date: Oct 2006 Posts: 538	Re: What's it for? Brekelefuw, Do you know what the screw is for?

11-18-2007, 09:29 AM	#13 (permalink)
confuoco Pianissimo User Join Date: Nov 2007 Posts: 184	Re: What's it for? Got any pictures of what you are describing?

11-19-2007, 08:25 AM	#15 (permalink)
crowmadic Mezzo Piano User Join Date: Oct 2006 Posts: 538	Re: What's it for? It came to me in a dream last night. The screw I'm talking about does keep the valve guide in the track of the valve stem as Vulgano Brother mentioned. It also fits into the slot inside the casing that stops the valve from spinning. Could that screw also be influential in angling the valve, and thereby be a source of correction for valves that drag when all other potential causes are elliminated?.........crow Last edited by crowmadic; 11-19-2007 at 08:29 AM. Reason: adding a sentence

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