Posted: Wed Mar 27, 2019 3:41 pm Post subject: Red Rot and Yamaha
Our lead guy has a Yamaha YTR 83-10Z that had some red rot pop up on the tuning slide just at the top of the curve (as opposed to the bottom curve near the water key). I told him I would make a post and ask if anyone knew where to obtain a replacement tuning slide. Suggestions? Anyone have one they want to sell?
Also wanted to see if we could get some detailed, factual information going here on red rot. There was a great posting of such info at another site -which has recently disappeared.
While red rot is dezincafication, does it always occur from the inside out? Are there true cases of it on the outside, but nothing inside? His appears as pinkish spots on the outside, but haven’t confirmed there is any deterioration on the inside. Also, the location of his red rot seems unusual as other parts of the horn would be more likely to be exposed from playing. _________________ Steve
Olds, Kanstul, Bach
Joined: 29 Apr 2008 Posts: 2450 Location: New York City
Posted: Wed Mar 27, 2019 3:52 pm Post subject:
Replacement OEM parts should be widely available from a variety of sources, perhaps from the local repair tech or music store. I'm sure someone could order one for you.
MK Drawing also sells their own aftermarket tuning slides for 8310z horns and some on this forum have enthusiastically recommended them, although I have not tried them.
Get it checked out by a tech. If it's just corrosion on the outside of the tuning slide it's likely not even red rot. I once thought one of my Bach slides had red rot and it turned out it just needed a polish. Problem solved.
Posted: Wed Mar 27, 2019 4:57 pm Post subject: Re: Red Rot and Yamaha
stevericks wrote:
Our lead guy has a Yamaha YTR 83-10Z that had some red rot pop up on the tuning slide just at the top of the curve (as opposed to the bottom curve near the water key). I told him I would make a post and ask if anyone knew where to obtain a replacement tuning slide. Suggestions? Anyone have one they want to sell?
Also wanted to see if we could get some detailed, factual information going here on red rot. There was a great posting of such info at another site -which has recently disappeared.
While red rot is dezincafication, does it always occur from the inside out? Are there true cases of it on the outside, but nothing inside? His appears as pinkish spots on the outside, but haven’t confirmed there is any deterioration on the inside. Also, the location of his red rot seems unusual as other parts of the horn would be more likely to be exposed from playing.
Often the reason for red rot is a local defect in material which can be caused/exacerbated by drawing and bending of the pipe. Are the pink spots appearing on the outer or on the inner radius of the tuning slide?
Your lead guy probably got red rot from leaving his horn on a stand when not using it. All of the water would accumulate on the top of the tuning crook, and after a long period of doing this, voila, there is your red rot. If you swab out the horn, which is really drying it from the inside, you won 't have this problem.
Often the reason for red rot is a local defect in material which can be caused/exacerbated by drawing and bending of the pipe. Are the pink spots appearing on the outer or on the inner radius of the tuning slide?[/quote]
Thanks. First time I have heard about red rot from drawing and bending pipe. Can you elaborate more? I’ll have to look again at rehearsal next week as to the exact location. I was always under the impression it typically started from the inside and worked its way outward. However, I have occasionally seen horns with pink/white spots on the outside. That always seemed strange as the lacquer or silver should offer some protection. _________________ Steve
Olds, Kanstul, Bach
In regard to brass pipe produced by hot extrusion the article says (bold emphasis is mine):
Quote:
Defects such as surface cracks, tears or delamination may occur during processing if the die is insufficiently or excessively heated, if the ram speed is too high, or if there is high friction between the billet and die walls (4). Intergranular cracking may also occur due to local cooling of impurities at grain boundaries. Residual stresses occur within the extruded part by non-uniform flow patterns or by mechanical working and increase its susceptibility to stress corrosion cracking in specific environments. In addition to these stresses that may already be present in the material, stamping also induces residual stresses where corrosion can occur preferentially. Lead is often added to brass (0.10% in Cu30Zn) to increase machinability (3).
The reference above discusses hot-drawn brass pipe.
I believe similar issues should be encountered when a pipe is cold-drawn.
When referring to the inner and outer radius, I meant "on the inside" and 'on the outside' of the large radius of the tuning slide. If you cup your hand over the tuning slide that is the outer side. If you pull the tuning slide out, you are pulling (mostly) by the inner side. In bending the pipe, the outer and inner radius sides experience different stresses. The outer side is stretched, while the inner is partially compressed and partially stretched, often leading to a 'wavy' pattern that needs to be straightened out by rolling or hammering.
This is very clearly seen in the video from a Polish brass repair shop in which they form a new leadipe for tuba, filling the pipe with molten lead and then bending the pipe. The wavy inner radius is created in spite of pipe supported from the inside by the solidified lead. Skip to 4 m 45 s (and turn off the audio):
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