Yet another JZ-6 Bass VI

[tommycarlos]

And... the dream is over. I don't have the equipment or skills to fix the mistake I just made...

[tommycarlos]

I actually did file the point off... thought I had it made.

Added the adapter bushings, lined everything up, carefully drilled the guide holes... lightly screwed in the first screw (not all the way so I could manoeuvre it), added the second screw... all good... went to tighten the first one and heard the crack

[Simon Barden]

Yes you do, as long as you have a clamp. All is not lost.

Knock out the bushing. I often use a drill bit for this that's just bigger then the inside of the bushing.

Get a brush and some Titebond, thin some Titebond a little bit with water so it flows more easily, brush it into the crack and clamp it. leave it clamped for 24 hours. If necessary, cut some triangles of scrap wood so the clamp isn't holding at an angle. You can always use a workmate to clamp it if you haven't got any other suitable clamps. You may see a faint line, afterwards, but nothing too horrendous.

Next time, drill the pilot holes a bit bigger and wax the screw threads. Make sure the pilot hole is bigger than the solid core of the screw but smaller than the overall thread diameter.

[tommycarlos]

Hrm. Even assuming I could just glue it back (I think I could clamp it OK considering the angles)... how could I re-fit the machine heads since the hole for the screw will still be right along the "fault line", as it were? Would it be a strong enough bond to drill the machine head screw hole a bit bigger, wax the screw and re-fit it?

[Trevor Davies]

It should be OK. Just a learning experience! Plus an opportunity to improve your guitar building skills.

"Would it be a strong enough bond to drill the machine head screw hole a bit bigger, wax the screw and re-fit it?"

It should be fine (and possibly the strongest part of the headstock). I would get the glue in the gap while the screw is still in place (as it will keep the gap larger), then remove the screw, then clamp it.

The tuner hole may need to be redrilled after. I would possibly try a slightly (real slightly - maybe sanded/filed) bigger hole for the bushing (I feel the bushing contributed to the crack), and add a few drops of CA glue to keep it in place if it is a bit loose (the CA could also to strengthen the fault line).

Others may suggest different options.

[Simon Barden]

With an ‘along the grain’ crack, the glue is a lot stronger than the lignin holding the cellulose fibres in the wood grain together. So as Trevor says, yes, it will certainly be strong enough to hold. You may even want to prise the crack open a bit more in order to ensure getting glue on all the surfaces before clamping.

It’s where another pair of hands might come in handy so you don’t struggle with getting the glue in.

[Simon Barden]

When you clamp the headstock, it needs to be tight, but not over-tight as you don't want to squeeze all the glue out of the joint under pressure (just the excess in order to bring the two surfaces together in close proximity). The hand-operated quick-grip clamps are probably best, as you can get a reasonable clamping force, but not as much as with a standard G-clamp. Of course a standard G-clamp is fine, but you've got to resist the temptation to just tighten it that bit extra.

[Dikkybee007]

I have a little bit of experience in fixing similar cracks in kits and this is how I have done mine with success. I only get my glue from Bunnings and seeing as they dont sell Titebond I use Selleys Aquadhere exterior glue as it is supposed to be stronger than wood and I have used it on about 6 guitar necks and have had no problem. I know you cant use steam to remove the neck but in the 20 years I have used it I have never had to remove a neck but if I had to I know how.

I have used a flat bladed screw driver and wedged it into the crack and opened it slightly to get more glue into the joint. I wouldnt water down this glue as it will reduce its strength and the glue has the right viscosity to allow it to flow into the crack. I normally use some tooth picks that I shape so they will fit a little bit further into the crack and allow me to push the glue into the crack.

The glue container has a nozzle that allows you to squeeze the glue into the crack as long as you hold the nozzle tight against the wood at right angles and move it slowly along and control the flow. I then use the tooth pick to force the glue into the crack and may even apply the glue numerous times to make sure it has entered the crack on both sides. I also use a squeegee or flat plastic strip to force more glue into the crack and I put some masking tape on the under side so the glue doesnt just go onto the floor or table top but that depends on how wide the crack is. I do both sides the same way to make sure the crack has plenty of glue in the crack.

I then remove the screw driver or wedge, what ever you use to hold the crack open, and then apply a sliding F clamp as it has soft plastic covers and clamp the parts together and use a damp cloth to remove any excess. I leave for about 24 hours or longer, depending on the weather, remove the clamp and it is fixed.

As for the screw holes I use a set of vernier calipers to measure the minor diameter of the screw but you can get a scrap piece of wood and drill holes until the screw slides into the hole and then go back a size or 2. I have a set of drills that have 0.5 millimetre increments and I always go to the next size above the minor diameter. As long as the hole is smaller than the outside diameter it will hold. Just dont over tighten, remember half a turn before it strips the hole out. An old Tradesman's joke.

Due to the gap being larger between the tuners due to the holes being further apart than necessary you could have used a washer under the head of the screws to hold the tuners in place. Always use a piece of tape or a permanent maker to set your depth as you dont want to drill through the head but always make sure you go deep enough so the screw end doesnt hit the bottom of the hole.

If you need to drill new holes for the screws just use either a toothpick or wooden skewer with a bit of glue to fill the holes and redrill the holes and they will be strong enough to hold the screws. Any oops is always fixable and you dont need special tools to accomplish a good outcome.

[Simon Barden]

Any wood glue is stronger than the wood for a given value of stronger. If gluing endgrain to endgrain, then the joint won’t be as strong as the original wood if bent at right angles to the grain, but it will still be a stronger bond than the wood when bent parallel with the grain. In this instance, the loading is mainly a compression one from string tension, with just a little outward force across the grain due to the bushing and the screws, which the glue will easily cope with. I’ve seen lots of luthiers use water-thinned Titebond to get in cracks which has held perfectly well. Obviously there’s less glue per unit volume, and it takes a bit longer to dry and harden, but it will still work fine.

[tommycarlos]

Thanks everyone. That’s very encouraging. I am going to give it a try. *crosses fingers*