Grenadilla Repair

[Stephen Howard]

I use 3M 3792Q - the high melt-point version (not 3791LMQ, which is a low melt-point glue).
It's an industrial glue, so you have to buy it in large quantities - though you sometimes see small batches pop up on ebay.
It's designed for use with an expensive glue gun but I tend to just heat it with a flame or, for smaller jobs, grate or slice it into small shreds.
You can probably find similarly specced glue sticks from other manufacturers - and they'll probably work just fine for DIY jobs.
Other than that the pellets from Music Medic will be fine.

 

[PigSquealer]

@Stephen Howard the OP lives in Southern Florida. That region is well known for a large variance in temperature and humidity.
I wouldn’t be surprised that summer to winter temperatures span from 7°C to 40°+. Humidity from 10% to 99%.
40°C and rainy wouldn’t be unheard of.
Considering these environmental conditions what’s the best gamble on a wood joint repair? Pin and high tech adhesive combination? Wood can be a challenge making any repairs….

 

[Stephen Howard]

I've never been convinced that pinning works terribly well. I've seen way too many pinned cracks that have opened up again. Carbon fibre banding is perhaps the best bet - but if the wood wants to move there's really not a great deal that will stop it.

 

[PigSquealer]

I've never been convinced that pinning works terribly well. I've seen way too many pinned cracks that have opened up again. Carbon fibre banding is perhaps the best bet - but if the wood wants to move there's really not a great deal that will stop it.

Honestly I’m not surprised. I don’t see how pins would really work unless two were installed in a X pattern. Locking against each-other.
External band support would be my choice. Adhesives only have so much flexibility. Good for sealing an air leak and the support being an external wrap.
Wood cell structure in itself has challenges no matter the application.
Besides learning the printing tradecraft from my father. I have six years of formal training in cabinet-millwork and furniture making.

It’s amazing these wood tubes drilled out like Swiss cheese last at all. Even after years of curing before machining.

 

[PigSquealer]

If anyone is interested…

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[stitch]

I don’t see how pins would really work unless two were installed in a X pattern. Locking against each-other.

That's how I was taught to do it.

 

[PiccoloPirate]

Growing up learning to fix the necks of string instruments that were dropped,
any "pinning", using proper materials, were angled to prevent movement.
When I do full depth precision joinery, with designs like the Saint Andrews cross, the red lines, show how I imbed the rods,
to lock the wooden parts together.

Will get back to how I did all the work on the Grenadilla, but I used those glass droppers, to add the Hot Stuff on top of the powdered wood.
That was after I used just the glue, to stabilized the cracks.

 

[PiccoloPirate]

It might not always be a X pattern, but angled to prevent movement.
I helped a family that has been Colonels and Generals, since the founding of the USA, repair a musket stock.
First was to remove the wrong glue, then which glue and how to pin it to stay together.
That was followed with work on the '60 class sloop, after a bad lightning strike.

 

[djarossens]

First up, that crack on the right of the bell tenon isn't 'small'. Also there's some distortion of the wood. This isn't wonderful.
On the flipside the wood has probably done moving, and cracks around the bell tenon joint tend not to be worrisome.

For the properly fine cracks bog-standard superglue isn't thin enough. You'd want something like Hot Stuff or Rocket Hot thin superglue. This stuff is incredibly watery. If you tip a bottle of it up upside down you'll likely lose most of it in a second or two. So, decant some into a small container (I use a bit of foil scrunched up) and from there dip something like a cocktail stick in it and use it to apply the glue.

As for the larger crack you can go in with the thin superglue in the first instance and then follow it up with an epoxy adhesive mixed with powdered grenadilla. Heat the resin to thin it beforehand. It's not worth trying to reposition the distorted section (you can try if you like) - best bet would be to skim the bore once the glue has set...or just leave it be (it'll be fine).

Degrease the wood beforehand with cigarette lighter fluid, and give it plenty of time to evaporate.

Thank you, I have a couple of old German clarinets squirreled away waiting for some love to bring them back to life, will certainly need a lot of cleaning to get started and then onto the cracks. so far I have been working on building up the tip rails and filling the teeth marks on their respective mouthpieces.
I saw on these old instruments the joints were wrapped in a "string"/ cord and not glued cork. Can you shed some light on that for me please?