 The Clarinet BBoard
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Author: Chris P
Date: 2011-08-24 17:33
What kind of carbon fibre is best used - thread or loose fibres? I would think either thread or thin braided cord would be best than using loose fibres due to there being more strength with the fibres either twisted or braided.
I've searched online and eBay for carbon fibre fishing line and carbon fibre thread but can't find any in black. Although it probably doesn't matter what colour it is (as it'll be hidden beneath filler), but can someone point me in the direction of a supplier?
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: SteveG_CT
Date: 2011-08-24 18:13
Chris,
I haven't used it for instrument repair but I have made components out of carbon fiber on many ocassions. For a banding repair I would recommend the use of loose fibers (often referred to as "Tow") instead of thread as it will lay down flatter and provide a more consistent surface. For this kind of repair I doubt you would realize any benefit from using a woven cord or tape.
I'm not aware of a supplier in the UK, but you can buy the stuff in the US for around $15 for a 50yd length.
http://www.fibreglast.com/product/24K_Carbon_Tow_2293/156
If you want to look for another supplier closer to you I would suggest searching for "graphite" instead of "carbon fiber" as this may get you more hits.
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Author: Caroline Smale
Date: 2011-08-24 18:55
What I use and recommend is often sold as "Tow" (name confused me at first) and comes as a fine ribbon about 5/6mm wide and only a few fibres thick. They are not really loose fibres but band of continous strands.
Because the fibres are so thin this ribbon will readily reshape and fit into say a 2 or 3mm wide groove without having to actually separate the strands.
I have used this mainly with epoxy but have experimented also with superglue, pros and cons for each. Epoxy tends to be messy unless carefully handled and adjacent surfaces protected but is easier to use.
Superglue is quicker but can be tricky as sets so fast so careful planning and application is needed.
I think resulting strength is probably equal (and more than enough).
I bought a supply (100 Metres - probably more than a lifetimes!) some years back from a firm called Fibretech based then in Lancing W Sussex. Haven't checked to see if their website still there but should be easy to trace.
I think they also sold it in smaller quantities of say 10M and this would be ample for quite a few repairs.
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Author: tictactux ★2017
Date: 2011-08-24 21:08
> I would think either thread or thin braided cord would be best than using
> loose fibres due to there being more strength with the fibres either twisted
> or braided.
That is a misconception, if you don't mind me elaborating. The most strength you'll actually get from parallel threads. Braiding/twisting/meshing/whatever adds "redundancy strength", ie if a single thread breaks, it still (by means of friction etc) adds strength up and downstream of the point of the rupture, and it adds (mechanical and thermal) elasticity as, when the "rope" is twisted or subject to uneven temperature changes, the load is distributed more evenly to all the participating threads.
However, in a "banding" application, the threads are embedded in a rather stiff and immobile substrate (eg epoxy) and the whole strand is not subject to movement or twisting an thus wouldn't gain from twining of some sort.
--
Ben
Post Edited (2011-08-24 21:10)
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Author: Chris P
Date: 2011-08-24 21:50
I was mainly concerned with the initial tying of the band whether twisted/braided cord would withstand getting the tension on better than parallel fibres - that's unless there's no need to make a loop in the end to thread the rest of the strand through to create a tight binding before the rest of the strand is wrapped around while at the same time being held in place by the glue.
So is the end glued into the slot and the rest wrapped around itself under tension (but without being looped at one end and the rest of the strand threaded through and pulled back on itself to keep it taut)?
The only downside to carbon fibre banding I can see is the same as flush banding - you may have to cut a slot right through the logo. But that's a fairly minor aesthetic downside in comparison to having metal bands showing.
I'm not that far from Lancing, so I'll check to see if Fibretech are still there and make a visit next time I'm over Worthing.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Caroline Smale
Date: 2011-08-24 22:53
I can only give you the method I use, there may well be other options.
I usually apply a minute dab of super glue in the slot and use this to anchor the end of the carbon fibre band (it's easier to stretch a small straight band between ones fingers and ease this down onto the glue in the slot for a few seconds then once anchored cut off the waste end with a scalpel tip. I use method this whether the rest of the job will be done with cyano or epoxy.
It is only neccessary to use moderate tension anyway as one isn't trying to compress the wood merely stabilise, and once the epoxy or cyano has set the band becomes as firm and strong as steel but without any risk of contricting the bore.
For small items like barrels and especially Eb barrels I usually cut a quite shallow groove and build the carbon just above the surface and finally finish in the lathe.
My theory here is that (apart from the small amount of wood one has to work with) the nearer to the surface the band is fitted the more effective the band is in restraining the wood from future movement.
In this respect it's much better than pins which by design must be fitted much closer to the bore.
I always tell my customers why I am doing it this way and to treat the small visible surface of the band as a "feature". Surprisingly so far they have all agreed that they actually like it that way.
Just checked Fibretech and they still seem to be in business and offering 10M rolls of tow.
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Author: Chris P
Date: 2011-09-07 22:44
I went over to Lancing today and couldn't find Fibretech anywhere on Crabtree Lane - none of the other businesses there knew of them and they're not even listed in Yellow Pages or any directories and the landline number wasn't recognised (and I didn't have their mobile number).
Almost went home empty-handed but paid a visit to the model shop on the Broadwater Road http://www.sussex-model-centre.co.uk/ and they sell carbon fibre tows there. A bit more expensive than Fibretech sells it for (if you don't add their postage cost) but at least I've now got some.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: jasperbay
Date: 2011-09-08 15:37
As to bedding the carbon fiber in epoxy or CA 'superglue', I now use only thin CA glue, as its hardness more closely matches grenadilla wood, it penetrates and bonds better than epoxy,and some grenadilla sawdust can be sprinkled on to add color-texture-strength. Not all thin CA glue is "quick-set". If overly quick setup time is a problem,I often use old 'expired' superglue (really cheap from e-bay suppliers in Hong Kong or China) that takes as long as 24 hrs. !! to set up, unless you spray on some 'accelerator' that speeds setup to 10 minutes or so. Additional sawdust/CA glue can be added to low spots later, as it bonds to previous layers well, and can then be sanded like wood or hard rubber. I dab CA glue on with a toothpick- more control than out-of-the-spout.
Clark G. Sherwood
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Author: Chris P
Date: 2011-09-08 21:38
I prefer using superglue and wood dust as a filler over epoxy anyday. There are some epoxies that are designed to give a good finish, but like any epoxy they take several hours before any work can be done, whereas most superglues offer instant workability.
Not that I don't use epoxy - it's best for glueing in replacement tenons and I seal and bond detachable sax bells with it as it allows plenty of time to move things if need be.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Chris P
Date: 2011-09-12 16:39
Attachment: carbon_banded_ct_bell 004.JPG (161k)
Attachment: carbon_banded_ct_bell 003.JPG (155k)
I've just tried it out on a scrap CT bell that was split from top to bottom and definitely pleased with the result, using carbon fibre tows and superglue, then finishing off with superglue and wood dust.
Without the socket ring on I forced a file handle inside and nothing disastrous happened. Without the banding (but only glued together) the chances are the crack would've opened up again.
Attached are photos taken in direct sunlight to show up the filler.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: clarnibass
Date: 2011-09-12 17:02
Attachment: cracked.jpg (49k)
Attachment: repaired.jpg (78k)
Here is a Selmer bass clarinet I did a while ago. I used the fibers from J. L. Smith. It was possibly the worst joint I've seen, with about eight cracks. The first photo shows one of the cracks after a previous repair by someone. It has three or four bands and several pins.
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Author: Chris P
Date: 2011-09-12 17:19
Carbon fibre banding will be ideal for ringless bells and barrels on both clarinets and oboes.
I've seen several wooden B&H clarinet bells that have split as they don't (often) have bell rings fitted (well, very rarely in the UK anyway), so turning a slot in the bell rim (where there's already a decorative slot) will be an ideal place to band them, then another band either in the middle or above the logo will be enough to keep it all held tight.
The full Boehm CT I've got in pieces also has a split bell socket, so I'll carbon band this one as well.
When it comes to top joints, the only downside is if the band has to go across the logo, but there's no reason why the slot can't be milled around it (as well as making detours around pillars and toneholes) as it's not as though it's a metal band being fitted and has to be dead straight.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
Post Edited (2011-09-12 17:33)
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Author: Chris P
Date: 2011-09-13 14:47
Attachment: Buffet_F69090_top_joint 001.JPG (165k)
Attachment: Buffet_F69090_top_joint 002.JPG (167k)
Attachment: Buffet_F69090_top_joint 003.JPG (165k)
Attachment: Buffet_F69090_top_joint 004.JPG (166k)
Just a few more photos where I've had another go, but this time on a Buffet full Boehm top joint that's split on opposite sides and right through to the bore. The 1st and 2nd photos are as it was right after cutting the slots (which could go all the way around) and 3rd and 4th photos are after banding, filling in, filing down an papering up prior to polishing.
(I realise I should've left the flash on my camera to show up the filler better)
It has been pinned previously, but the joint sounded dead when held by the tenon and tapped with a knuckle or file handle as you'd tap a tubular bell. After banding and filling the remaining cracks and slots, the joint sounds like a single, fracture-free joint again!
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
Post Edited (2011-09-13 18:45)
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Author: SteveG_CT
Date: 2011-09-13 16:19
Very impressive results. I'll have to try this out on one of my P-M's that has a crack at the end of the upper joint.
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Author: Chris P
Date: 2011-09-14 21:17
The two scrap CT bells I experimented on won't go to waste - the second one which still has the logo in full glory is currently being used for my early Series 9 A while it's having its socket ring silver plated.
The first one that was split in two and the logo is worn out (which was my first attempt at carbon fibre banding) will be turned into an oboe da caccia bell (for use on my Marigaux cor anglais) by shortening the socket and fitting a nickel silver socket liner, plus having a socket ring turned to resemble a Marigaux cor anglais socket ring as it never came with a socket ring. The outside shape of most CT bells is perfect for this application as is the bore shape which is almost a true cone.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: jicaino
Date: 2011-09-17 14:31
Hey guys sorry I'm chiming on late to the carbon fiber party
What I do after having experimented with tow, then trying like Chris to find a fine braid, then using filaments and braiding it myself before banding, is buy a piece of CF woven cloth and use the tows that form the woven. It's easy to unwoven, and they (the tows you get out of cloth) are nicely sized to create outstanding repairs (they're thin, like 2.5mm)
For finish I go 2 ways: I band until I reach the surface and leave it visible, or dust. I've been preferring the visible repair because it shows it's repaired, it shows your skills with how you handled the repair, and because you can create a very strong reinforcement without having to cut a deep grove in the wood. I've banded near sockets and the result is great.
I use Loctite 406 (very low viscosity cyanocrilate glue) and band like this: I use a small drop to hold the tip of the "tape", then place the glue over the fibre and wrap tight. You can do about a revolution at a time once you have practised enough.
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Author: Martinwoodwind
Date: 2012-11-06 09:26
Hi.
I used 3K tow ordered on line from 'orders@easycomposites.co.uk. supplied in 100m lenghts @ about £12.00. I have just used it to repair a Buffet Prestiege Bass clarinet on the bottom joint. Using a lathe I cut a 1/4mm recess into the body and again using the lathe by hand wound the carbon fibre tow until flush with the body. I then used SP106 polyester resin to fix. the jount was then left for the weekend to cure. cleaning up was a matter of sanding. The repair can be left matt. I used Le Tonkinios varnish as this remains flexible.
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Author: Tony F
Date: 2012-11-06 11:10
Going back to the days before the availability of carbon fibre materials, a friend in UK repaired his 9 series Selmer using kevlar string and black epoxy. The string was/is easily obtainable. He teased it out into threads, wound them into grooves machined into the body of the upper joint, applying warmed black epoxy as he wound. The following day he completed the epoxying and when finished and polished it was almost undetectable. Probably not as strong as carbon fibre, and because the material is white care needs to be taken to completely bury it in epoxy. It's obviously quite strong enough, because 25 years later the clarinet is still in use.
I've used the same technique when laying up 3 layer laminated timber veneers for boatbuilding. The second layer is grooved using a router in a zig-zag pattern, the kevlar string stapled in place in the groove and then the 3rd layer of veneer laid in place with epoxy. Makes for an immensely strong structure.
Tony F.
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Author: Johan H Nilsson
Date: 2015-10-18 15:37
Attachment: 20151016_210434.jpg (1289k)
Attachment: 20151016_210515.jpg (1294k)
Attachment: 20151016_215615.jpg (1281k)
*bump*
I bought a clarinet 2nd hand which I knew was cracked at the top of the upper joint, from the register key through the tenon, but turned out to be severely cracked on both sides. There is a difference of 0.7 mm on the *outside* diameter, so the body is like an egg. The cracks on the inside are 0.5 mm wide. The owner has tried to cover them with glue. Very clumsily as seen on the pictures. The cracks have then widened further.
My question on the thread's subject is if carbon banding preserves its form, not only its circumference. I would believe that if I put the body in a vice to remove the egg form and applied the carbon band, the carbon band body would crack if the wood wants to resume its egg form.
The other question is if this instrument can be rescued at all. The upper part of the upper joint is vital for the clarinet's tuning. A barrel with 0.1 mm wider/narrower bore can make a big difference to the tuning. I am not sure how an oval bore affects the tuning. It does not change the volume very much.
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Author: clarnibass
Date: 2015-10-18 22:53
>> I would believe that if I put the body in a vice to remove the egg form and applied the carbon band, the carbon band body would crack if the wood wants to resume its egg form. <<
It might but not necessarily. Only if the force is too much against whatever is holding it in place (in this case the bands) and the only place that it can release this stress is by cracking. It can definitely happen, but it's more likely that it won't.
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Author: Johan H Nilsson
Date: 2015-10-19 04:19
I could try what Silversorcerer suggests but I need to get rid of the glue first. Even if the owner just painted over the crack with glue, some of it probably went down into the crack and will prevent it from closing.
If I don't hear other suggestions I think I will try and remove the glue on the bore with a soldering iron and then fraise up the crack with a Dremel tool using a thin drill.
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Author: Johan H Nilsson
Date: 2015-10-20 16:43
Silversorcerer, will the gelatin attach to the wood and prevent the crack from widening or is it just a sealing/filling material?
Post Edited (2015-10-21 01:37)
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Author: clarnibass
Date: 2015-10-21 09:09
>> If I don't hear other suggestions I think I will try and remove the glue on the bore with a soldering iron and then fraise up the crack with a Dremel tool using a thin drill. <<
Assuming you mean a regular twist drill, it could work, but it's also pretty risky. Twist drills generally work terribly for anything other than drilling and are very likely to break if used as a "fraiser". Especially with a Dremel (or equivalent) tool which is not a precision tool with relatively poor control. Just be aware of the risk if you do this.
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Author: Johan H Nilsson
Date: 2015-10-22 02:26
Clarnibass,
Yes, I can only press the drill along its axis and make many small holes, then perhaps flatten the angle and let the head "fraise" what is between the holes.
When I look online, there are hard metal milling bits available and perhaps they are more feasible. There are v-shaped ones which might be small enough. The only problem I see is that I have to work with a very flat angle, so the widest part of the bit will determine the width of the new crack.
I have to get rid of the glue somehow, right?
Once the body has regained its form I can fill what is left of the crack. That is easier if I have widened the crack.
An alternative to Silversorcerer's method should be to oil the bore while it is cracked and let the body regain its form. Then clean the cracks with alcohol and finally fill them with a grenadilla pulver and epoxy mixture ("greenline").
Thanks for your input!
Post Edited (2015-10-22 02:32)
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Author: Johan H Nilsson
Date: 2015-10-25 19:25
The seller accepted a return, so I will not need to bother. I doubt this clarinet would have played well. The upper part of the upper joint is where bore dimension is crucial.
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