 The Clarinet BBoard
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Author: jim lande
Date: 2005-12-14 02:03
A while back there was a thread with the suggestion that one could dissolve a pivot screw using alum and not hurt the post. Apparently this is an old clock repair trick.
Nobody sells pickling alum any more. (Apparently the fact that it is mildly poisonous is being taken more seriously.) I bought a pound of Potassium Aluminum Sulfate, which is a slightly different type of alum. It us used as a mordent.
Don, Doctor Slick, Others --- please advise before I do something bad.
Will it dissolve the steel screw?
Will it hurt the silver plated brass/nickel post.
Do I just make a saturated solution using a bit of water and heat?
I promise to wash my hands and not pick my nose and wear glasses. Any other safety precauctions?
Thanks.
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Author: ron b
Date: 2005-12-14 02:57
Hi, Jim -
I find Alum readily available at a local Raley's grocery store (supermarket) right here in Sacramento, CA. Little spice jars of it are found in the spices section next to the cooking oil and mustard. McCormick ALUM. Bright red lid with yellow label with red and black lettering. I bought six containers last summer (when it was still "legal"???). I haven't heard of it being on any dangerous substances list, at least not here... yet :|
For your project you'd probably need about two cups of water, maybe less, and a couple TBS alum -- maybe start with half a jar, add more if that's too slow. The process will work with room temp but is hastened by keeping the solution hot but not boiling. Thrift store crock pots (cheap, used) work fine for this. It attacks ferrous materials. Check it every half hour of so. Be patient.
You might ask your local tech to give you a junkbox plated key with spring, post and pivot, or something like that to experiment with first -- but I don't think you'll have any problem with plating or brass material.
If I'm not mistaken, Aluminum Sulfate (don't know about the potassium part) is the active stuff that devours iron and steel.
It might sting if you get it directly in your eyes, otherwise I don't think you should have any difficulty.
- r![[cool]](http://test.woodwind.org/clarinet/BBoard/smileys/cool.gif) n b -
______________
p.s. - I still have a couple of jars left if you're desperate. Contact me off line and I'll smuggle some over your way.
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Author: Shorthand
Date: 2005-12-14 03:03
Definitely a Dr. Henderson question. I don't think there's anyone that knows clarinet chemistry any better.
Personally, I have no idea of the metalurgy of posts vs screws (except that most screws seem to be simple high carbon steel.)
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Author: Fred
Date: 2005-12-14 03:26
An alum solution buffers out at pH ~ 3.9 , so I wouldn't hold my breath while waiting for it to dissolve the screw.
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Author: ron b
Date: 2005-12-14 04:17
Have you tried penetrating oil and heat, Jim? That, and patient determination, work 99.9% of the time for me. No messy crock pots and tedious clock watching. You just squirt and heat a few times while twisting that ugly little monster outta there.
*************************************
A quick browse of some 'net info sites this evening revealed to me that:
If you really wanna get nasty about the 'iron' stuff, and venture into dangerous territory, you could go at it with sulphuric acid. It might also pickle your post :[hahaha) i.e.: Nickel-Pickle, available at jewelry making suppliers, has a penchant for dissolving copper (trust me on this)... so, a nickle silver post could disappear in a cloud of nickel-pickle if it has a substantial enough copper content.
Although both Potassium Aluminum Sulfate and Aluminum Sulfate are called "alum", they are not exactly the same. Potassium Aluminum Sulfate is more commonly used to stabilize dye to fabric. You might find PAS at a hobby/fabric dyeing type store. dunno....
Personally, I prefer the milder and safer approach (heated alum solution).
- ron b -
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Author: Bassie
Date: 2005-12-14 10:16
This very interesting. The idea is to remove the steel without hurting the brass / nickel / silver it's stuck to, right? Sounds like electrochemistry - the presence of the brass / nickel / silver should accelerate the dissolution of the steel - or rather, the steel should dissolve sacrificially.
In fact, the dissimilar metal contact is probably why it's stuck in the first place. Things like that should be assembled with plenty of lubrication and kept dry...
As an answer to your question: my guess, therefore, would be: 'don't leave it in too long!' - once the steel is gone the remaining metal might be subject to attack.
Let us know how it goes, eh?
Post Edited (2005-12-14 10:20)
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Author: Gordon (NZ)
Date: 2005-12-14 10:46
Alum is also available from horticultural supplies, and maybe garden centers. Some Asian grocery stores may have it very cheap.
It seems to make little difference whether one uses what is sold as "aluminium sulphate", or potassium aluminium sulphate.
I was taught that the term "alum" refers to a double salt, involving both a metal (or radical) of valency 1, and also a metal of valency 3, as a sulphate. It may well be that potassium aluminium sulphate is loosely called just aluminium sulphate in non-scientific circles.
I have heard technicians report on its success, and no reports of it attacking silver or post metal. It seems to need heated soaking for many hours, say in a container in a crock pot. The mixture is about 6 oz per pint of water, the water topped up as it evaporates.
However I would wait for our resident chemistry expert, Omar, to chip in here.
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Author: Don Berger
Date: 2005-12-14 12:54
YUP - I agree with most of what RonB, Gordon and others have said above. We all will be interested in LOH's comments and short lecture on alum chemistry, when he has the time from his works on Boehm System improvement. Looking at them from a historical standpoint, his efforts deserve future recognition, IMHO. Yes alums [generically speaking] are double salts of aluminum sulfate and therefore are of acidic character [the combo of a strong acid with a weak[er-end] base], usually with a Group 1 cation, Na, K, Cs, as Fred said, pH 3.9 IS quite acid. Without any textbook or actual research, I'd think it would attack nearly every metal it could contact, Fe, Cu, Ag, etc, perhaps not Ni or Cr [like H2SO4 !] {Remember "Johnny was a chemist's son, ----"]. I suggest to those, who dont know of it, to look up the tables/descriptions of the chemical elements, for explanations of elementary inorganic chemistry. To quit wandering around [here], and look for Omar's comments, off-hand, Jim, possibly a DROP of concentrated Na or K alum might loosen a ?rusted-in? pivot screw/rod, BUT, I'd be afraid of leaving it active for more than a couple of hours, as it might cause other accelerated corrosion. The OLD [slow] method of continued application of rust solvents and screwdriver trials would be my recommendation. Early morning thots, Don
Thanx, Mark, Don
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Author: Gordon (NZ)
Date: 2005-12-15 00:04
A DECENT screw driver, along with penetrating fluid and heat has never failed for me for a pivot screw. Failures come from damage done by inadequate screw drives, but even then, I re-form the screw slot, INSIDE the post, by using a tiny burr in my dentist drill (Dremel might do).
When a screw is wrecked and still won't come out, most technicians drill through it, which often removes it in the process, and use a broach to jam inside it and unscrew it. Sometimes screwing in a tap will extract the remaining drilled-through thread. Of course, care is needed with all these operations in order not to damage the post.
I think the occasion when a technician resorts to chemical removal is very rare indeed. I have never needed it. But I would use it for a threading tap that was broken off inside a crucial non-steel metal part.
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Author: ron b
Date: 2005-12-15 00:40
Gordon wrote, "I would use it for a threading tap that was broken off inside a crucial non-steel metal part."
Interesting. I comtemplated doing the alum treatment, next day or so, as I broke off a bit trying to drill out a broken threaded end on a metal clarinet. It involves the register key post. Man, that thing is wedged in there like granite. I think now, however, that I'll just remove the top and make a replacement to silver solder in place. Alum process seems too awkward in this situation.
:(unnngh....
- r b -
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Author: jim lande
Date: 2005-12-15 01:56
I have been dipping Hoppes #9 on the screw and then heating (using a Volton induction heating soldering iron) then adding more Hoppes and leaving for a day or so, and trying again. The problem here is that someone else ruined the pivot screw before I had a chance.
Hoppes also has been recommended on this list.
I have been afraid of using a drill because I can't drill a straight hole, and probably wouldn't hit it dead center, either.
A dental burr. That sounds like something I can find on the internet. I have been looking at dremel tool cut-off wheels. Of course there is the same issue: will I cut a slot in the screw or just disfigure the post. I suppose I could practice on some junkers (and then soak what's left in alum.)
I was thinking of daubing on a concentrated solution and heating, and repeating. I don't want to soak the whole thing in a crock pot because then I would have to replace all of the springs.
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Author: Mark Charette
Date: 2005-12-15 02:53
jim lande wrote:
> I have been afraid of using a drill because I can't drill a
> straight hole, and probably wouldn't hit it dead center,
> either.
Find a friend or a shop with a drill press and a (leather covered) vise. It's the safest way to drill a perfectly straight hole, and keeps small twist drills from bending when you're drilling those tiny holes.
I used to make jewelry as a hobby, and had a mini-drill-press for my Dremel.
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Author: ron b
Date: 2005-12-15 03:52
I like Mark's suggestion of the mini-drill press setup. My drillpress, while a 'bench model', is pretty big and mounted on a stand. I had the instrument set up in a vice on the drillpress table and the bit was aimed dead on. Then operator error came into play and I levered the drill into the work just a little too fast, enough that -- bing! -- the tip of the tiny drill broke right off, wedged tighter than I imagined possible. I'm pretty sure now that a smaller power tool (drillpress) would be much better for these smaller jobs.
Lesson: you just can't hurry these kinds of projects
...live and learn :(sigh....
- rb -
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Author: Gordon (NZ)
Date: 2005-12-15 08:59
I find that the more delicate any machine task, the more hand control and less machine control one needs.
For this task, I use a dental handpiece (Dremel would do) held by hand.
If at all possible, I drill from the point end of a pivot screw, because then the drill is helping to screw the pivot out, and this does often happen because all the forces are in the right direction, unlike using a screw driver. (The heat of the friction helps too.)
First I ensure a small flat surface at the end - using a diamond wheel in the handpiece with both work and handpiece hand-held.
Then I use a tiny round or 'inverted cone' burr in the handlpiece to make an indentation in the centre of the end of the steel, again with work and tool hand-held.
I adjust this indentation by eye, until it is perfectly central. You would need a pretty fancy jig set up to equal this centering by machine!
Then I put the suitable diameter drill bit in the handpiece, and drill away. At least the drill STARTS central, because of my indentation. I hold both the handpiece and the item in my hands, drilling horizontally. I constantly monitor the straightness by eye, turning the work every so often to check another plane.
If the drill wanders slightly (from uneven hardness in the material, meeting the the thread itself, an unevenly sharpened drill, etc) I easily see it and compensate.
I can monitor the pressure exerted far better than in a drill press, and hence ensure that there is no buckling of the drill, which would send it off course in a drill press or even break the drill.
Because I am holding the work in my hand, I can accurately feel the resistance the drill is encountering, and can quickly react if it is jamming (eg from swarf accumulation, or as it emerges out the other end, or encounters the groove in the screw head, etc) and likely to break.
I would never use a drill press for this work, although I have a very accurate one. Far too little control! We have magnificently sensitive 'feedback' nerves in our hands, connected to our eyes and muscles via a processor. What priceless equipment. A shame not to use it!
Post Edited (2005-12-15 09:04)
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Author: BobD
Date: 2005-12-15 10:41
Having tried Gordon's methods on one problem screw I can caution any one contemplating it . Gordon, like all pros, makes it sound easy. I gave up on my screw and simply continue to play the horn as is. If you are looking for alum you might look for a "styptic pencil" which we old timers used to stop the flow of blood from shaving with a straight razor. You can still get them from Caswell Massey, I believe. I wouldn't get alum solution anywhere around my clarinets.
Bob Draznik
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Author: Mark Charette
Date: 2005-12-15 10:58
Gordon (NZ) wrote:
> I would never use a drill press for this work, although I have
> a very accurate one. Far too little control!
I would always use a drill press for this kind of work when I worked on jewelry. The hand is way too uncontrollable in trying to drill a small straight hole. The dremel drill press gave me perfect control (or nearly so). I never went through all those steps above (except grinding a tiny flat if there was a break that was jagged).
So, as you can see, everyone's mileage varies ...
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Author: BobD
Date: 2005-12-15 13:55
Good thing you didn't become a dentist, Mark...
I've tried both ways and still can't get adequate control. Excellent eyesight is a prerequisite.
Bob Draznik
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Author: Gordon (NZ)
Date: 2005-12-15 14:26
I think drilling a rather long hole (for its diameter), as large in diameter as possible through a threaded silver-steel rod embedded in a softer metal that is of a shape difficult to align accurately in a holding device, is a rather different operation from the holes I drilled in jewelry items I made.
So our mileage may not be THAT different, Mark. :-)
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Author: Mark Charette
Date: 2005-12-15 14:33
Gordon (NZ) wrote:
> I think drilling a rather long hole (for its diameter), as
> large in diameter as possible through a threaded silver-steel
> rod embedded in a softer metal that is of a shape difficult to
> align accurately in a holding device, is a rather different
> operation from the holes I drilled in jewelry items I made.
>
> So our mileage may not be THAT different, Mark. :-)
Gordon,
Probably not - but I used that setup on Weber carburators and other miscellaneous hard to clamp/long rod/inserts harder than post materials, too. So the operations were essentially identical.
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Author: Gordon (NZ)
Date: 2005-12-15 22:37
I think the different factor is the diameter of the drill. When the drill size gets down to close to 1 mm, there are major issues of buckling and also of breaking.
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Author: jim lande
Date: 2005-12-19 02:10
Gordon
I have been looking at dental burrs, some of which apparently will fit a dremel tool. It seems that I have two choices: a 1/4" disk and a very tiny wand. Both could cut a slot. I can see that the former would carve into the post. (I have a clarinet where this obviously was done.) I can see where the latter would require better eye hand control. Which type burr are you using?
Some burrs are carbide and some are diamond. Which are you using?
I also see that some places sell these things in quantity. How many pivot screws can you cut before replacing the burr?
The screw that started this off is not yeilding to cycles of penetrating oil/solvent and heat. The slot was pretty damaged when I got it.
thanks
Jim
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Author: Gordon (NZ)
Date: 2005-12-19 14:01
".....I can see where the latter would require better eye hand control."
Yes, that is true. It also needs VERY high precision bearings in the handpiece, and preferably a very light handpiece that puts the fingers holding the tool close to the work, no heavy flexidrive, and say 30 or 40 thousand rpm. That is why I use a dental lab motor/handpiece unit.
" Which type burr are you using? "
I managed to acquire a large quantity of small steel burrs when a dental training school closed down. They have a 2.3 mm shaft, about 40 mm long. The tip is an inverted cone (larger diameter at the end than further towards the shaft). and that is the well-used name for that type. The end is flat. The size I prefer is about 0.62 mm diameter at the end, and the cone is not much longer than that.
"Some burrs are carbide and some are diamond. Which are you using? "
These ones are steel. If you used diamond for this sort of work, you really need to turn the bit 10 times faster, and have water squirt form the handpiece to clear away the removed metal so as not to clog the tool. You're getting onto expensive equipment there! I'm not too sure that tungsten carbide is made that small. It would be very brittle where the tip attached to the shaft.
" How many pivot screws can you cut before replacing the burr? "
I don't know how many slots one burr will do. Perhaps only 2 or 3 for these steel burrs. They are very cheap from dental supplies. And because I have enough to last at least my life-time, I'm not worried how long they last or don't.
I want to make it clear that I only use these burrs if I want to re-cut a slot while the screw is stuck inside the post.
(When I make pivot screw or rods, I use a very cheap coping saw, the short sort with the bent 1/4" wire frame. Eclipse was the traditional brand name. The set on the teeth on these blades is achieved by the blade having a wavy edge. I grind off the waves on the sides of the blade, and then this blade is just the right thickness for sawing the slot in screws and rods.)
The screw that started this off is not yielding to cycles of penetrating oil/solvent and heat. The slot was pretty damaged when I got it.
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Author: BobD
Date: 2005-12-19 14:32
"The screw that started this off is not yeilding to cycles of penetrating oil/solvent and heat. The slot was pretty damaged when I got it."
Exactly my situation with a register key screw and the clarinet had belonged to a professional who evidently had a passion for using the wrong screwdriver. The one thing one never knows beforehand is if the binding is in the thread, the head area or in the tube. Once you have buggered the slot you in trouble. I continue to play the horn and dream that one day the screw will just work its way out. LOL
Bob Draznik
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Author: Gordon (NZ)
Date: 2005-12-19 20:08
"...The one thing one never knows beforehand is if the binding is in the thread, the head area or in the tube...."
Although there may well be binding in all three locations, the main binding will be either in the tube or inside a post.
Diagnosis is simple: Operate the key while looking closely at the head for movement relative to the post. If it moves, then the binding is in the tube; otherwise it is in a post.
"....I continue to play the horn and dream that one day the screw will just work its way out. LOL...."
Perhaps it is not THAT funny. If it is rust, then as it progresses, the job will get greater, because destructive removal may be required. Furthermore, if the main binding is in the tube, it means that the pivoting and hence the wear is occurring inside both posts, possibly aided by a very abrasive slurry of oil and rust dust.
So a single problem may be gradually developing into several, with posts needing to be bushed, and/or a new pivot rod made, not that it takes too long to make pivot rods.
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