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Martin Dovetail Graft/Scarf Repair
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10137&t=50842
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Author:  DanKirkland [ Wed Jul 25, 2018 10:34 pm ]
Post subject:  Martin Dovetail Graft/Scarf Repair

An interesting one that just got finished today, hadn't seen anyone photograph this before so I figured you guys might find it interesting.

I had previously asked for help in getting out an *extremely* annoying portion of a broken neck on a 69' D35. Every friggin crevice had been flooded with titebond of the water resistant variety. the top half of the neck had been cracked and repaired 5 times in the past year so I wanted a more permanent fix. The only reason I could see this happening that often was that the bottom portion had been fit so tight that the upper portion of the neck was moving when the weather would shift. The bottom half wouldn't budge so of course something had to give. I could be wrong on this, just a guess.

Brian Howard had suggested I drill out the neck joint to get steam where it needed to go. This was an excellent suggestion and as a result the portion finally was free after some encouragement.

To replace the lost wood I decided to cut out the drilled section of the dovetail, and add an angle to the cut to get a slight scarf joint on the gluing area. Cut the scarf past the break area so that it rejoins the two halves with an actual piece of wood instead of relying on the glue joint alone on the break line. Glue on the replacement wood, cut it to size, refit, glue, done.

After I had cleaned out the old glue and reglued it to the upper half of the neck this is what I was left with. I hadn't thought to take a picture until after the first cut was made. You can see the crack line where the drill holes end.

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You can see the slight angle in the cut. Since there's nothing but end grain in this section the scarf was necessary to ensure a strong glue joint.
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Some custom clamps to hold the graft in place.

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Some people hate these little planes, I love them for jobs like these. My Japanese friends say it's my "kung fu finger workout"
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And done.
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Fun repair, hadn't done it before this this but I think it'll work. Time will tell. I know the client well so if anything happens I'll know right away.

Author:  olmorton71 [ Fri Jul 27, 2018 3:14 pm ]
Post subject:  Re: Martin Dovetail Graft/Scarf Repair

Nice


Sent from my iPhone using Tapatalk

Author:  Haans [ Fri Jul 27, 2018 3:30 pm ]
Post subject:  Re: Martin Dovetail Graft/Scarf Repair

Looks like that chisel has been 'round the block...

Author:  DanKirkland [ Fri Jul 27, 2018 6:31 pm ]
Post subject:  Re: Martin Dovetail Graft/Scarf Repair

Haans wrote:
Looks like that chisel has been 'round the block...


It likely has. I have no clue on it's story. It's my main big one for large jobs.

Image

Author:  Clinchriver [ Sat Jul 28, 2018 6:18 am ]
Post subject:  Re: Martin Dovetail Graft/Scarf Repair

Got my fingers crossed for you :mrgreen:

If it breaks again its time for a new neck. I recently reset the neck on a 1977 HD28 that for some reason had been reset poorly 18/19 years ago and glued back with some really weird waterproof glue 3/4's of my time on the project was cleaning up old glue.

Author:  DanKirkland [ Sat Jul 28, 2018 10:45 am ]
Post subject:  Re: Martin Dovetail Graft/Scarf Repair

Clinchriver wrote:
Got my fingers crossed for you :mrgreen:

If it breaks again its time for a new neck. I recently reset the neck on a 1977 HD28 that for some reason had been reset poorly 18/19 years ago and glued back with some really weird waterproof glue 3/4's of my time on the project was cleaning up old glue.


I agree. He just can't afford a new neck at this point.

I seriously don't understand why some of these guys just drench the entire thing in glue.

Author:  Alex Kleon [ Sat Jul 28, 2018 8:20 pm ]
Post subject:  Re: Martin Dovetail Graft/Scarf Repair

Nice and tidy!

Alex

Author:  DanKirkland [ Mon Jul 30, 2018 9:10 am ]
Post subject:  Re: Martin Dovetail Graft/Scarf Repair

Alex Kleon wrote:
Nice and tidy!

Alex


Thanks for the compliment.

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