Eight Million Headstock Breaks In The City; This Is One of Them.

[sdshirtman]

I know there's already a ton of headstock break threads on this forum, but after posting a picture to the "whats on your work bench" thread there seemed to be a bit of interest in one more so I'm going to add yet another one. Full disclosure. I've done a fair amount of broken headstock repairs in the past but I'm not nearly as seasoned at breaks like this as BCRGreg, Roman or Freddy G. So take this thread with a grain of salt. If anyone has any suggestions along the way on how I could improve I'm all ears.

That being said, I like a challenge and this is what I would consider a reasonably bad break. To make things worse the customer informed me that its not the first time its been broken.

Both pieces fit together pretty well but there's not a lot of bonding surface to work with here. Because of the break location its going to be a bit challenging for me to apply even longitudinal clamping force to get a good glue bond and squeeze out.

I thought about how I was going to tackle the clamping portion of this repair for a while. I settled on the idea doing a sort of "H" or I-beam configuration in conjunction with a wedge matching the headstock tilt angle in an attempt to lower the longitudinal clamping force and keep it in line with the neck.

Heres another look of what I'm working with.

More to follow soon.

 

[Chakalawaka]

Quite the Herculean task! Looking forward to see the process of how you're gonna fix that

Good luck!

 

[MrYeats]

A lot of work will go into that to make it LOOK nice but it eill never have any strength.

 

[TheHarleyMan2]

Here is one video of a guy fixing that type of break.

Here is another

 

[Skyjerk]

If that guy came to my I could do a build thread of my politely recommending that he take it to someone else

Based on some of the repairs I've seen our lutherie superstars tackle, this one should be repairable. I just wouldn't want to try it myself

 

[MrYeats]

nothing is impossible.

 

[Barnaby]

Very cool. I've done a few of these now, but am always really interested to see new ways of dealing with things and learn something every time. I will be watching and enjoying!

 

[sdshirtman]

Here is one video of a guy fixing that type of break.

The carbon fiber rods is a new one to me as well as the way he did the rubber tubing. I'm curious as to which would be stronger, carbon rods or wood spines. I also wonder how much clamping force rubber tubing can generate.

I've seen several of this guys neck break repair videos from the second vid you posted. His jig is pretty slick (and expensive) but I have some reservations on how much material he has to take from the back of the neck. Does running 10" splines down the back of the neck add that much to the repair? It's debatable. *sound of a can of worms opening*

-Continuing-

As I said in the first post I wanted to do sort of an I-beam shape clamping jig. The tops and bottom of the "I" attached to the headstock and neck respectively then connect the two with clamps. I wanted to keep this as simple as possible.

First step was to make the bottom part of the "I" for the neck. A piece of pine scrap laying around will do. I roughed out the profile of the neck in the center on a spindle sander.

I don't want this to slip during clamping or leave impressions on the back of the neck so I want to to match the profile as close as possible. A bit of 120 sticky paper on the neck and some sanding will give me an almost exact fit.

A bit of 1/8 foam on the back attached with some spray adhesive will keep the finish safe and give me a bit of grip.

I made a crude clamping caul for the fretboard side. It might be worth noting that I shaped the underside of the caul to match the fretboard radius. It wasn't like I was using a gorilla grip on this clamp plus mahogany is relatively soft so I didn't this it was necessary to add foam here.

With that completed I have the first half of my clamping jig done.

Its probably pretty clear where I'm going with this now. Lunch is over. Back to work. More to follow. . .

 

[cmjohnson]

I'd be thinking about a two spline repair path for that. Which I'd kind of like to attempt, at some point. I'd use my knee mill to mill the spline slots because I'm not a chisel wizard.

 

[TheHarleyMan2]

The carbon fiber rods is a new one to me as well as the way he did the rubber tubing. I'm curious as to which would be stronger, carbon rods or wood spines. I also wonder how much clamping force rubber tubing can generate.

I've seen several of this guys neck break repair videos from the second vid you posted. His jig is pretty slick (and expensive) but I have some reservations on how much material he has to take from the back of the neck. Does running 10" splines down the back of the neck add that much to the repair? It's debatable. *sound of a can of worms opening*

Yeah I didn't like his idea of rubber tubing to bring in the headstock, I thought it was interesting the way he inserted the carbon fiber rods through the headstock and neck!

The other video the guys jig is pretty cool, but definitely overdid the splines on the repair! Yeah like gold prospecting, someone has a new tool out and they want to charge and arm and a leg for 500% more than what the tool costs to make!

Anyone can make a similar jig like the guy in the second video to make a clamping jig and router spline guide.

 

[lowatter]

Yeah that jig is really well thought out and ideal EXCEPT for that honking length of splines he used. I don't see the benefits of splines that are that long. If you watch the video to the end you'll see and awesome finish blending job done to it and the repair is hardly noticeable.

 

[sdshirtman]

I'd be thinking about a two spline repair path for that. Which I'd kind of like to attempt, at some point. I'd use my knee mill to mill the spline slots because I'm not a chisel wizard.

I agree and its coming.

Yeah that jig is really well thought out and ideal EXCEPT for that honking length of splines he used. I don't see the benefits of splines that are that long.

The biggest benefit I can see with his rig is speed. A mill might work well but figuring out how to position the guitar in there and clamp it down seems like it would be pretty time consuming.

Continuing with the second half of the clamping jig. I'm going to try not to over explain myself because pictures will explain most of what I ended up doing, but here goes.

It would be easy enough to clamp a piece of wood maybe 8" wide to the headstock and use the two over hanging ends on either side to clamp the two pieces together, but doing so would move the applied force of the clamps off center with the longitudinal plane of the neck and fold the break over. Kind of like closing a clamshell cell phone. This is a problem I saw with the first video that TheHarleyman2 posted with the rubber tubing. You can see where he uses clamps in the center of the neck to pull the bands in line with the neck but its still looks a bit off center. This may have worked well for him but I digress. Anyways, I wanted to move that center of applied force directly in line with the longitudinal plane so I could get some good clamping force on the break. Thats the theory at least.

I did this by attaching a wedge to the top of the headstock. I finished off two Les Paul's a few months ago and had some off cuts around the shop that that were already at the correct angle. I won't try and explain it any further. Here is the second part of the jig.

I was going to clamp this thing on but figured using dowels would be much simpler. The round notch is so I have some room for some small cauls on either side of the actual break during glue up.

This should allow me to get be a bit more pressure on the actual break without folding this thing over.

You can see here what I was after. I pushed these together by hand as tightly as possible and wiped off the excess squeeze out and applied cauls on either side of the break. Applying the two outside clamps was a bit of a juggling act but simple enough. After the two outside clamps were set I temporarily removed the cauls on either side of the break to wipe off the additional glue squeeze out which was considerable. No monster force here but a fair amount of pressure. In case you're wondering I used Titebond on this.

A picture is worth a thousand words. This shows what I was trying to explain in the beginning of this post a bit better.

24 hours later and out of the clamps. The joint is pretty strong as it stands but I wasn't about to start wanging on it super hard to find out how much so. I used some CA to fill in the hairline cracks.
The razor marks are measurements from the truss rod recess so I have an idea where to place the splines.

Ok I'm going to take break and go shoot a few coats of lacquer on another guitar. To be continued shortly.

 

[Freddy G]

Nice going! It's coming along just fine. It's a lucky thing that the finish is black. You will be able to make that repair invisible. I would go with splines as wide as you can make them.

 

[fumblefinger]

Just a thought, when I did a spline on a banjo neck (yeah, I know) I used my drill press. I chucked a dremel bit up, set the depth stop, and then slid the neck under the bit. It gave me better control than I would have had with a router. After making several plunges to get the majority of the material out, I set the bit and slid the neck back and forth against my guide block. Then made a sanding block the size of the slot and cleaned it up a bit with that. Came out pretty well.

 

[moreles]

I would have been tempted to remove the fingerboard and spline it from the front face, laminating a somewhat thicker headstock facing for strength. Your approach is more elegant and less disruptive. Looks like you have it under control. Nice job. Hope break #3 never occurs. Knock on wood. Ooops.

 

[sdshirtman]

Continuing.

Next up is making the channels for the splines which is pretty straight forward.
I recall BCRGreg mentioning in one of his HS break threads that he doesn't like the idea of using a router so close to a truss rod and thats why he uses a Dremel tool. I'd have to say I'm in the same camp. Using a heavy power tool turning at 15,000 rpm on something like this makes me a bit nervous. Although I've looked, I can't find any actual pictures of his process. (Thanks photo bucket). I'm genuinely curious how he gets his routs so straight and clean by hand. Heres how I'm doing mine.

In the last picture I posted you can see where I marked out how wide the truss rod nut recess on the back of the headstock. Using that as a guide I simply drilled four holes by hand using a piece of tape as a depth stop.
The blue tape is going to act as a guide.

Again I don't know exactly how BCRGreg uses his Dremel during his process but I'm using mine to just hog out the majority of the wood.

After the majority of the material I was removed and using the tape as a guide I cleaned up the edges with chisels.

Which leaves us with this.

Splines ready to be installed. These fit pretty snugly and I don't want to confuse them during glue up so specific sides and orientation get marked on the tops.

Clampy clamps.

After some filing and sanding to match the contours and shape of the neck.

Next comes some sanding sealer.

 

[Frankg11]

This is awesome, very nice work.

 

[sdshirtman]

Continued.

Maybe worth noting. I really didn't feel like breaking out the spray equipment the day I did this so I just used Mohawk rattle cans. No gloss black sitting around either. Since I'll be shooting clear over this flat black will do. After I shot the black I let this sit for several days to let the lacquer gas off, settle in and shrink. I wet sanded level with 6oo grit using naphtha to avoid any swelling on the screw holes.

After sitting for a few days to check for shrinkage I start shooting clear coats on the front and back. After I shot the clear coats it gets set aside to sit for a few weeks to allow for more shrinkage.

After that its just a matter of wet sanding and a quick buff. I don't bother with working up through lower grit paper. I just go at it with 2000 again using naphtha to avoid any potential swelling.

You can kind of see the truss rod cover has been repaired from being split in two during the first break that was repaired. The customer didn't want it replaced (or the nut). Also worth noting; I could have buffed this out to a bit of a higher gloss but the rest of the guitar was really beat to hell and I wanted to keep some continuity.

Always fun giving a guitar a new lease on life. Thanks for looking.

(Edited for some typos).

 

[jkes01]

Looks great, nice job!

 

[Tweaker]

Holy crap, that's amazing. I'm impressed! You guys make buffing the lacquer seem so easy, I may have to break down and try lacquer in the near future. If that truss rod cover got replaced, you'd never even know there was a repair. Very nicely done.