 The Clarinet BBoard
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Author: BobD
Date: 2003-07-22 18:42
I had trouble removing the rod screw on the register key of a recently acquired LeBlanc Infinite clarinet. To make a long story short I find that all the rod screws on this horn are non-magnetic and seem to be relatively soft compared to "drill rod", for example. Any clues as to the alloy used will be appreciated since I haven't encountered this before.
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Author: ron b
Date: 2003-07-22 19:02
Hi, Bob -
What color is the rod screw? Are the pivots also non-magnetic?
I'm by no means a fountain of information in this area but I've seen brass pivots on Monique saxes. I haven't seen or heard of them being used anywhere else - yet.
- r![[cool]](http://test.woodwind.org/clarinet/BBoard/smileys/cool.gif) n b -
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Author: BobD
Date: 2003-07-22 21:23
ron: haven't checked the pivots but am guessing they are "the usual" high carbon drill rod with a black finish. The rod screws are silvery color just like their high carbon drill rod counterparts. Certainly not a copper/brass color.
This is not a newer horn. Sure surprised me......but helped explain the easy tendency to damage the screw slot.
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Author: Gordon (NZ)
Date: 2003-07-22 22:44
Stainless steel is commonly used by some (many?) current manufacturers.
Some types of S/S are slightly magnetic; others not. It has the advantage of being LESS susceptible to rust, but it is not as good as steel as a bearing material.
You had trouble getting it out? Was that because of rust, gum deposits from inappropriate oil, bent rod or tube, misalignment of posts, inappropriate threads, wrecked screw driver slot, blunt screw driver, insufficiently large and robust screw driver, previous inappropriate application of Loctite or equivalent, weak hand of operator, .......
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Author: BobD
Date: 2003-07-23 12:00
Thanks Gordon. Type 303 stainless would be the most probable grade but this screw acts softer than 303. The slot was already buggered up when I received the horn(along with a few others) and I impatiently proceeded to make it worse. Now, after using penetrant, heat and patience I am still unable to budge it and am opting to drill it out, remove the slot end post and so on. I suppose it's possible that a prior owner used loctite, or inadequate lubricant resulting in galling, or that the thread fit is wrong. The material does "act like" nickel silver,however, and I haven't run across such in the past. More interesting than frustrating at this point. Thanks again.bob
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Author: Gordon (NZ)
Date: 2003-07-23 13:32
Perhaps it is an obsolete, inferior, softer grade. even without a name.
Have you tried penetrating fluid & heat, alternating over a few days?
Is the rod jammed in the post(s) or the pivot tube, or both?
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Author: BobD
Date: 2003-07-23 20:37
Gordon,thanks for your assistance. The key pivots perfectly, so the binding is in one or both posts. Yes, I've used Ferrees penetrating fluid and local heat via a soldering iron to the posts over more than a few days. The slot is long gone. I've used a left hand drill bit with pressure trying to bite in to no avail....and I've even ground down the tip of the smallest available screw extractor.....no soap. I am at the point of believing it's galling now and no fluid or heat will attack that. My guess is that it's 203 or 303 stainless which LeBlanc thought(rightly so) would offer more corrosion resistance than 416 but they didn't do their homework on galling and in addition probably used the alloy with inadequate cold work. This is not an uncommon mistate in other industrial applications of stainless. Thanks again. bob
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Author: ron b
Date: 2003-07-24 03:32
Just a thought - if the slot end is nearly gone and the metal is softer than steel, maybe you could drill by hand just a wee bit into the hinge tube using a collet or something like that. Then bending the key upward to just clear the pillar, you may be able to wobble key off. You might, just *might*, without further bending, get enough leverage to cautiously unscrew the rod.
- ron b -
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Author: Gordon (NZ)
Date: 2003-07-24 10:59
1. I use a very small round (say 0.5 mm diameter) dental burr to reconstruct screw driver slots sometimes.
2. If you use some gutsy pliers with enormous squeeze, such as .....
http://www.knipex.de/language/en/header_front.php
you can squeeze the pivot tube against the pivot rod, then rotate the tube & rod while being squeezed, to free the rod in the post. I have made minute jaws from steel so that the squeeze is on a cylindrical area from two sides of the tube, hence much less chance of bruising the metal.
3. Failing that, I would drill out the steel within the non-threaded post. I start with a hole a bit smaller, then enlarge it at the key side of the post, using a small round burr in my dental handpiece (use Dremel). Wrench the key to break the last bit of steel, unscrewing the other post in the timber, key attached, until the key is free of the non-threaded post. Then remove the non-threaded post and pull the key off the rod.
Hope that makes sense.
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Author: BobD
Date: 2003-07-24 15:02
Yes, that makes sense and it's probably what I will ultimately have to do. Afraid the "squeezing the rod" thing is a bit dicey for my talent. Thanks much,bob
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Author: jim lande
Date: 2003-07-24 19:46
I have come across one non-magnetic pivot screw in an old metal clarinet. It looked like either silver or german silver.
What does 'galling' mean in the stuck screw context and why is this a problem for stainless steel?
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Author: BobD
Date: 2003-07-24 21:09
jim, galling is a phenomenon characteristic of "300 series" stainless steels by which they tend to "self weld" to themselves and some other alloys when rubbed against them. Anti-galling compounds are usually used as "lubricants" when galling is a potential problem. Silver plating is also sometimes resorted to as a preventive. The problem is most often encountered on screw threads. Maintaining a hard to define difference in hardness between the two mating materials is usually suggested as a preventive measure.
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