 The Clarinet BBoard
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Author: jasperbay
Date: 2010-04-22 17:47
Just finished bringing a nice Leblanc Alto 'back from the dead' by repairing several cracks in the throat area, the most common 'crack zone', and thought I'd jot down a few tips for DIY'ers.
Crack repair of wood clarinets nowadays is done almost exclusively with thin CA (cyano-acrylic superglue) strengthened with grenadilla 'sanding dust'. This glue (I get it from model-airplane hobbiist suppliers on E-bay, usually in the 2oz. size for @$10) adhers to the very oily/waxy grenadilla wood much better than epoxy, and can be sanded down with a popsicle stick with glued on sandpaper to a near-invisable repair. Often, a 'hairline' crack need not be "pinned", just CA glued with sanding dust added for strength and color match.
Using thin CA glue (I see little use for medium or thick 'gap-filling CA glue) can be a real pain-in -the-rear, since it has the consistency of water, but thats how it 'wicks' deep into the crack and does such a great job! CA glue suppliers often include tiny disposable application nozzles, sometimes these work, sometimes not. I use a technique that takes all the 'fear factor' out of applying superglue: First, drill a couple 1/4" holes in a block of lead (or plastic, steel, aluminum, your choice) with a 1/4" drill. This is your CA glue 'inkwell'. Put in a couple drops of glue, it won't harden for 10-15minutes. Your CA glue 'pen' is a large toothpick, or similar, sharpened to a 'chisel' tip. This you dip into the CA 'inkwell', it will hold something like a tenth of a 'drop', and allow you to place the glue safely and with precision exactly where you want it! As the glue 'wicks' into the crack, you will have to keep adding 'dabs' of glue, usually untill the crack won't take any more, and the glue starts to set. Sprinkle grenadilla sanding dust into the crack as you add more glue. (black walnut dust will work in a pinch, or ebony).
If the crack is seriously large, or may be subject to movement, you may want to "pin" the crack, with short pieces of threaded steel, available from Ferree's Tools. This will help stabilize the crack, and with CA glue should make a strong repair. I'm keeping my fingers crossed, have'nt had one open up again yet.
I like to 'degrease' the crack with MEK or laquer thinner, applied with a small brush, and blown out with compressed air. I believe this makes the repair a little stronger, but will remove any black stain sometimes present, and require more work later during final sanding/buffing/oiling. Also, its best to never sand with your fingertips, always use a flat sanding device like a popsicle stick with different grits of sandpaper (wet-or-dry automotive type works well) to avoid subtle dips, humps, etc. that result from fingertip sanding.
CA glue also works well for tightening loose posts, building up chipped tenons, filling in the holes drilled for "pinning", repairing mouthpieces, etc., etc. Go forth and repair!!
Clark G. Sherwood
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Author: knotty
Date: 2010-04-22 17:59
Thank you very much! just one question, where do you get Grenadilla dust? would Brazilian Rosewood or Ebony dust do? (I have plenty of those exotic woods)
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Author: David Spiegelthal ★2017
Date: 2010-04-22 18:29
If you have any broken barrels, bells or other wood clarinet parts, you can grind them to produce a nice little mountain of grenadilla dust.
Actually any dark wood dust would work.
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Author: jasperbay
Date: 2010-04-22 19:26
Dave's right, you pretty much have to 'sacrifice' and old broken part from a vintage grenadilla clarinet. This would be a perfect use for those idiotic clarinet lamps on E-bay, but make sure its wood. Ebony, or any dark wood would work nearly as well.
By the way, you can make two kinds of 'dust'; one is a steel wooly looking dust by sanding with coarse sandpaper lengthwise, the other a regular fine dust by sanding 'crossgrain'. Both are usefull in clarinet repair.
Clark G. Sherwood
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Author: Chris P
Date: 2010-04-22 21:09
All hail Superglue!
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: John Peacock
Date: 2010-04-22 21:58
I recently got some tips on crack repair from an expert. He too recommended superglue, but rather than sanding down the excess (it tends to spread quite a way sideways from the crack), he suggested polishing with steel wool. I tried this and it worked a treat: removed the unwanted glue and polished what was in the crack to a shine that matched the wood. Even though I'd never done such a repair before, it came out almost invisible. I think I'd worry that sanding with even the finest paper would scratch the surface of the wood and spoill the mirror smoothness you can get, especially on vintage wood.
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Author: Chris P
Date: 2010-04-22 22:21
After sanding you can buff the wood back to a bright shine - buff the area by hand with a rag and buffing compound.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: knotty
Date: 2010-04-22 23:04
I forgot, I buy pen blanks at Penn State Industries, Woodcraft, and Woodturners Catalog. (Google them) They have ebony blanks about 3/4" x 3/4" x 5" at reasonable prices. No Granadilla however but perhaps some other supplier might have it.
You can also get Super glues of various viscosities and even a rapid hardener and glue solvent.
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Author: Chris J
Date: 2010-04-23 00:43
You can buy bags of grenadilla wood dust (I think Ferree's sell them) if you don't have a donor bit of wood.
My glue 'well' is a small candle (tea light) in a pit from wax scooped out
You can buy very low viscosity CA to maximise wicking into tight spaces.
Obviously start at one end of the crack and wick the CA in 'til no more is admitted in that small area until you move along to the adjacent part of the crack and move along that way. Trying to wick into too long a length at a time runs the risk of sealing the crack superficially before CA can wick down.
Chris
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Author: jasperbay
Date: 2010-04-23 01:23
Sanding on grenadilla is done gently, with progressively finer sandpaper, ending with 600 grit. Then, most any buffing compound will finish it up quickly. Fine steel wool (4/0) works well too, but even better is bronze wool, available sometimes at Home Depot.
Clark G. Sherwood
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Author: clarnibass
Date: 2010-04-23 04:41
For the glue "holder" I use non-sticky paper like the back of stickers. I most often use a needle spring to put the glue. Re the wood dust, if the crack is very thin you can't really get any wood dust in it, and it will just form over the crack and you'll need to sand it off. The only advantage of wood dust is to make it look better, but there are advantages to not making the crack invisible. There are more and more repairers who think pinning is pretty much never necessary for any crack. It is an old fasioned method that was common long before good glues were avaialble. With excellent glues now, it is changing.
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Author: BartHx
Date: 2010-04-23 16:00
Bronze wool is also available from large marine supply stores (eg. West Marine). They use it to polish the bottoms of racing boats.
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Author: BobD
Date: 2010-04-23 19:21
I've used carbon black in place of grenadilla dust....
Bob Draznik
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Author: Gordon (NZ)
Date: 2010-04-25 06:17
It has to be quite a wide crack before any filler is called for, and before you can get any filler into the crack. Filler should not be used until the crack is almost filled with CA glue, otherwise the top of the crack is likely to seal before the glue has wicked to the bottom, as Chris pointed out.
Filler is used more for the gaping entry holes for those pins that some technicians now seldom or never use, as Clarnibass pointed out, or for re-filling chewed out screw or post holes.
For final buffing, rubbing firmly and vigorously over a denim-covered thigh is often sufficient. (Mills & Boon strikes again!)
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Author: dansil
Date: 2010-04-25 13:38
Hi Jasperbay
I'm fascinated by the use of "pins" to stabilize cracks. I've never seen pictures of such pins and have no idea how they are put into place. Are you able to post some pictures of the pins and what they look like once they've been installed, or at least describe the process.
Cheers, Danny
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Author: Gordon (NZ)
Date: 2010-04-25 14:31
They are threaded steel or stainless-steel rods, typically around 2 mm diameter, force-screwed through undersized holes drilled across the split, sometimes at slight angles.
The extra length is broken off just below the surface of the entry holes.
Then the entry holes (and exit holes if there are any) are filled with a back glue/filler, often made from blackened epoxy, or black timber dust and superglue, and finished such that there is little or no evidence of the invasive operation.
Of course the rods crosses the crack quite deep within the timber, quite close to the bore, so it is arguable as to just how much the pins stabilise the splits, which are actually typically at their worst close to the OUTER surface.
Modern glues arguably do a better job of stabilising splits than pins can. Of course, as with all operations, the success or otherwise is in the detail of how the work is done, no matter which techniques are used.
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Author: dansil
Date: 2010-04-26 01:57
Thanks for the information Gordon. It must take a great deal of precision to avoid drilling the pin into the bore as the thickness of the joints is somewhere between 3-4mm. How is the pin broken off below the surface of the entry hole? Or do the pins have a tiny "head" like a screw or Phillips screw but the same diameter as the shaft of the pin?
Cheers, Danny
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Author: Chris J
Date: 2010-04-26 02:23
I have only ever repaired cracks with CA before oiling the wood. This potentially freezes the crack in the most open position.
Then oiling the wood will move the wood again.
It would make sense to oil the wood (marking the crack first as it can close to invisible sometimes) and then wick CA into the crack - but I worry the oiling would make the CA bond of wood/CA/wood weaker.
Does it?
Where do you put the CA stage in the repair/restoration process?
I suppose this question is only aimed as those who believe in oiling the wood...
Chris
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Author: jasperbay
Date: 2010-04-26 04:14
I agree with the experts who have weighed in, that 'pinning' is seldom, if ever, nessesary with modern CA glue techniques. It also makes a fairly ugly repair, what with filling the entry holes, etc. I would pin only a really nasty crack, that looked like it really needed it, and as Gordon points out, try to keep your crossdrilled hole from crossing the crack too deep towards the bore. Try to cross the crack at about 1/2 depth (surface to bore), and use a shorter, finer diameter pin.
The pins (actually threaded 6" long rods available from Ferree's Tools) are 'notched with a file or grinder at the length you want it to break off at. If you notch too deep you risk it braking off while threading it into your slightly undersized pre-drilled hole. Try to avoid having an 'exit hole' if you can, makes the final job a little prettier! I also touched on (in the DIY repadding thread) how to mill a small depression at the 'entry wound', and CA glue in an insert of color and grain-matched plug of grenadilla. When sanded down and buffed, this fairly well hides the entry and exit holes, and can be used to beautify old pin and fill repairs.
To Chris J. , I glue before oiling, and finish oiling with a partial hardening (or polymerizing) oil, usually a modified Tung oil. This type of oil, while the subject of debate in the clarinet community sometimes, I feel helps to waterproof the wood, and minimize future oiling requirements.
Clark G. Sherwood
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Author: clarnibass
Date: 2010-04-26 04:35
>> Of course the rods crosses the crack quite deep within the timber, quite close to the bore, so it is arguable as to just how much the pins stabilise the splits, which are actually typically at their worst close to the OUTER surface. <<
I agree. But maybe the main purpose of pins is to try to prevent the crack from growing into the bore rather than help against the outer edge.
>> Where do you put the CA stage in the repair/restoration process? <<
Before oiling and prerably clean/degrease the crack before. Why would the wood moving after oiling be a problem, considering the wood will move at least as much, probably much more, when playing.
>> I agree with the experts who have weighed in, that 'pinning' is seldom, if ever, nessesary with modern CA glue techniques. It also makes a fairly ugly repair, what with filling the entry holes, etc. <<
It is possible to make those entry holes almost and sometimes completely invisible. Sometimes you'll get a tiny white glue "vain" when sanded but usually not and the surface is the same. I've filled holes that were impossible to find. I later changed my opinion and now consider it better to leave signs to where the pins are.
>> Try to avoid having an 'exit hole' if you can, makes the final job a little prettier! <<
I prefer to have through holes, not blind holes. A bit more work to fill double the holes but I prefer the advantages of having a through hole.
>> The pins are 'notched with a file or grinder at the length you want it to break off at. If you notch too deep you risk it braking off while threading it into your slightly undersized pre-drilled hole. <<
This can be a real problem. It's too easy for the notch to be a tiny bit too small or big. Too small and it won't break there. Too big is the main problem, you can get half stuck. Since the more threads are in the more force it has, it is likely to break when too little is left to easily grip and screw it back out. So I don't bother with a notch and instead grind the extra bit of the rod off with micromotor.
Though I'm really skeptical about the real benefits of pinning. Pinning is done with glue too, so no way for a repairer to know whether it is actually the glue that does the work. The only way is to pin without any glue and see what happens. I've seen pinning like this and the crack always re-opened when I played the clarinet, just less than it did before the pinning.
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Author: Chris J
Date: 2010-04-26 05:33
"Why would the wood moving after oiling be a problem, considering the wood will move at least as much, probably much more, when playing."
Here is my logic:
1. An instrument wood moves while playing - but within safe tolerances such that it does not crack
2. An instrument that has cracked has moved beyond the tolerances of the fibres of the wood
3. A cracked instrument has the potential to move back to an uncracked appearance with oiling
4. Glueing a crack seals it in that position
5. Oiling the wood after glueing will move the wood, but not move the now fixed crack
6. The fixed crack after oiled wood might produce other tensions within the fibre of the instrument that may compromise it such that another crack becomes more likely
Theoretical - but probably not borne out in practice?
Chris
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Author: clarnibass
Date: 2010-04-26 06:17
>> Here is my logic <<
I'm not sure if this is logic to follow. You describe it as if the wood moving from oiling is more and different from wood moving from playing vs. cold and dry. I think the clarinet moves most from playing and it moves in the same way. I don't think oiling is likely to move it back to uncracked appearance. Not playing for a while can do this.
Also the glue only attaches a small point of the circumference. In addition both the wood and glue can and will move from temperature etc. I think the different positions from oiling or not are very small in comparison with the movement from playing vs. dry anyway so it is likely that it is irelevant.
I think the only way around what you describe as a problem is to never play the clarinet. If you are overly concerned then you can oil first, degrease the crack, then glue. But it will still swell and contract more from playing anyway. Plus if something does happen, you can't "predict the future" and know what caused it e.g. if it does crack in a different place you can't know it was because you oiled or didn't oil it before gluing. Only a huge mount of samples under identical conditions can show something like this.
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Author: Gordon (NZ)
Date: 2010-04-26 11:52
I'm with Clarnibass on this one.
Furthermore, I think it would likely be weeks of oiling the bore before the oil got anywhere near the outside diameter where most cracking occurs.
If oiling closes cracks (and I'm not convinced it does), then this must surely happen by shrinking the timber near the bore. I would appreciate an explanation of how oil closes cracks. IMO cracks are caused by overmuch stress in the timber, during the conditions IN WHICH THE CLARINET IS ACTUALLY USED (combined with stresses naturally in the timber).
And for the oil advocates, is this a hydrophobic oil or hydrophilic oil (such as what Doctors Products and Naylor advocate)?
Post Edited (2010-04-26 11:59)
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Author: Caroline Smale
Date: 2010-04-26 14:28
During my training we were taught how to put the pins in hot so that they basically cut there own thread in a predrilled hole. This provided a very secure hold but is very tricky to get right and leaves no margin for error during the process.
For anything except small surface checks I am a firm believer in the carbon banding approach. This also provides the necessary support from virtually the outside diameter of the wood vs the pins which must be much closer to the bore.
I am not personally convinced that superglue can possibly provide a sufficiently strong mechanical joint as it is really trying to fix two vertically opposed surfaces i.e. a butt joint, and as any experienced woodworker knows this is a naturally very weak connection.
Superglue and wood dust are very good as a cosmetic finishing treatment.
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Author: jasperbay
Date: 2010-04-26 16:15
While Mr. Smale's view that CA glue+dust is of 'cosmetic value' only may seem a trifle pessimistic, there is much truth in what he says; I would agree that the glued crack has no awesome strength, if the wood wants to continue to move, its probably going to! Will pins help? Probably somewhat, but I think you'll have a hard time finding a repairman who will warrenty a crack repair very far into the future.
My experience is mostly with vintage clarinets, in whose internal stresses have long ago been worked out, and not a lot of strength is needed to both seal the crack, and stabilize it to some degree. This is hardly 'of cosmetic use only' as it allows me to play these old gals to my hearts content.
I've seen mention of the carbon fibre banding technique in other threads, does this use 'bands', or carbon-fibre thread wrapped around and stabilized with something like CA glue![[grin]](http://test.woodwind.org/clarinet/BBoard/smileys/smilie5.gif) , or epoxy resin?
An aside for Mr. Smale: I just picked up off the auction site a Leblanc alto (with swan neck) $155 US, with several repaired cracks in the throat area. Wish me luck!!
Clark G. Sherwood
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Author: Mark Charette
Date: 2010-04-26 16:21
jasperbay wrote:
> I just picked up ... a Leblanc alto (with swan neck)... Wish me luck!!
>
You picked up an alto? Your lifetime supply of luck was just destroyed.
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Author: jasperbay
Date: 2010-04-26 18:20
I know, an "Alto", black sheep of the clarinet world!! Its just danged unfortunate there are so many soprano players who have not found a "good" Alto to play, and appreciate their lovely tonal qualities.
Actually, after shooting black powder muzzleloaders competetively for 20 yrs, the alto's just keep sounding better, and the more I shoot, the better they sound! I suppose before I'm 'pushing up daisies' I'll have to lug around a bass clarinet everywhere.
Clark G. Sherwood
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Author: Caroline Smale
Date: 2010-04-26 23:28
Yes carbon banding (at least how I do it and I believe this is only option) involves using carbon fibre "tow" a narrow band of carbon fibres wound around the instrument usually in a shallow recess. I use expoxy to soak and strengthen/fix the fibre, have not used CA glue for this yet but it would probably work OK.
Best of luck with the Alto!!
In clarinet terms a "Nerd" is someone who owns their own Alto!!
(I own 3 - a mid 30's Bundy (Paris) with double octave mech.. bought in pawn shop in Woodstock for $25 in about 1965 - before Woodstock became famous... it also had quite a long pinned crack but this has never moved - mind you very little playing
- the Leblanc - still waiting to find time to make a neck
- a lovely German system from 1939 complete with engraved swastica on the bell - just couldn't resist it at the price.)
At my age I think it's maybe about time to retire gracefully to the lower regions and let a younger generation scream around above the stave.
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Author: jasperbay
Date: 2010-04-27 04:11
So we Alto and Bass fanciers are "dwellers of the lower regions". The term does have a nice ring to it!!
Your carbon fibre banding technique sounds much like the method I use for strengthening and/or building up a cracked or too small tenon . I've been using small diameter (finer than sewing thread) high-tech braided fishing line (the expensive stuff thats 10 times stronger than monofilament nylon) wrapping one or more layers around the tenon 'shoulder', underneath the cork (before replacing cork) or at the tenon tip (to make the joint less 'wobbly'). I use CA glue as a "fixative" since it bonds to grenadilla well, but must admit CA glue (at least the fast-set stuff) often gets a 'frosty' look, and doesn't 'level' at all well. If you try CA to 'fix' your carbon band, try to find some cheap- 'past its expiration date'- slow to set stuff, as it sets shiny. I got some old CA thin stuff out of HongKong that takes several hours to set (without spraying on some accellerant). Still doesn't 'level' like urethane or epoxy , but adheres well to grenadilla, and is "hard", more like urethane or fiberglass resin.
The 'Spectra' type microfibre-polyetholene is very low stretch, like dacron, but probably not so much as carbon fibre. I'll try carbon fibre thread if I ever find any, and give it a try.
Clark G. Sherwood
Post Edited (2010-04-27 14:57)
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Author: Gordon (NZ)
Date: 2010-04-27 16:00
Norman wrote, "...I am not personally convinced that superglue can possibly provide a sufficiently strong mechanical joint as it is really trying to fix two vertically opposed surfaces i.e. a butt joint, and as any experienced woodworker knows this is a naturally very weak connection...."
Any experienced woodworker will also know that if an along-the-grain surface is well glued to another along-the-grain surface, and later forced to break apart, then it is not the glue that fails, but rather the neighbouring timber itself that fails, splitting apart.
This is the same situation as for clarinet splits. In my experience if failure occurs, it is not the glued joint, but another location nearby.
(I agree that END-grain glue joints are not as strong as the surrounding timber. But this is because timber under tension is far stronger in this direction.)
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Author: jasperbay
Date: 2010-04-27 17:41
Gordon; Glad you weighed in on the subject of "just how strong is a CA-grenadilla glue joint?" since I'm sure your experience far surpasses my own.
I've glued a dozen or so barrels, bells, and UJ's: and have not yet had one open up again. Still, grenadilla is a very, very, difficult wood to glue, and its nice to hear that the crack-healing gluejoint has some strength. We may even be able to uncross all our fingers and toes someday!!
Clark G. Sherwood
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