Bolt-On Neck Problem

[Logan]

I am buiding my first guitar; a Stewart Macdonald dreadnought kit. I think I sanded too much off the top of my guitar when adjusting the sides due to a mistake I made earlier (using a radius to sand the top, and then having to try and re-flatten it with limited success...if I set a straight edge where the fretboard lays it is flat within that area, but the straight edge is off the guitar top by the time it reaches where the bridge will be).

As a result, I have this lip when I put the neck in place (is this what people refer to as the 14th fret hump?). So, the bolts are bottomed out and you can see that the neck is a 1/32 or so more proud of the guitar top. The tenon joint itself actually has some room that the neck could be moved lower, but the bolts obviously wont allow this to move any lower.

The edges of the neck actually sit quite well against the guitar sides to where if I didn't have this problem, I would be sitting pretty. The angle and side to side look really good...just too high.

So, potential solutions I was debating would be adding a shim to the bottom of the fretboard where it attached to the guitar top and binding the fretboard sides to hide this fix. I could also sand the top of the guitar neck below the fretboard, though this would potentially cause problems at the head of the guitar and having to re-route the truss rod channel and creating a neck that was too thin? And thirdly, I could glue in dowels to the pre-drilled holes on the neck-block and re-drill them very slightly lower.

Which would be the recommended method to fix a neck that sits too high? Is there another fix I am not thinking about?

[Logan]

By the way, I've been pleased thus far with how things are going and appreciate the help on this forum. I understand that the sanding goof early on is going to create problems with setting the neck and set-up and all sorts of things, but I'm generally pleased with how things are going and have plans for guitar #2 already - which don't involve screwing up the math on the sides. This is how things look thus far...

[David L]

I can't help you with your problem but I like your helper on the couch in the photo. BTW, what are your plans for #2?

David L

[Logan]

Thanks. Charley is a rock-star. I own a book and game store and he comes to work with me every day. I can take him on walks around town and people will scream his name from their car window as they drive by.

Guitar #2 is going to be a bloodwood dreadnought with cutaway - and the basic plan being to do as much by hand as I'm comfortable with, rather than relying on kit parts. Other than the added difficulty of shaping pieces by hand, the cutaway and type of wood / binding used will be the only thing different from #1. I want to keep things similar enough that I feel comfortable and not get to carried away changing the total guitar style / bracing / etc.

[johnnparchem]

I would wait for advice from one of the pros. If the truss rod nut is going to be in the guitar, do not shim. With that much of the neck sticking out you will have trouble getting to the truss rod to adjust it.

The guitar looks good though. Good luck!

[tippie53]

check your bolt hole alignment to see where you are held off in the joint. You are most likely held of at A: the bolt holes B: the bottom of the neck block. All you need to do is relieve the area that is effecting your joint. Not that big of a deal
john

[Tony_in_NYC]

Hey Logan,

The straight edge SHOULD be off of the guitar top by the time it reaches where the bridge will be, so you are good there. You really do not have a problem here. Like John said, sand a little bit out of the bottom of the mortise in the neck block and your neck will drop into place. You could also take a tiny bit off of the tenon on the neck as well. If you have a dremel and the little sanding sleeves, you will be able to remove the material needed from the neck block in no time. You may also need to make the bolt holes in the neck block longer, but probably not. Once you get the neck to sit flush, I would also check the alignment of the truss rod adjustment hole through the shoulder brace to make sure you can still get to the truss rod nut. ALso make sure your truss rod slot in the neck block allows the rod to sit down deep enough so that you can get the neck in without any issues.
One thing I will tell you is that your problem is not the 14th fret hump. It is a completely different problem, but easily fixed. Make sure all of your parts have clearance in the block and you will be fine.
Do not, I repeat DO NOT glue the neck onto the guitar yet, or ever really. But if you feel you must glue it on, wait until after you have the guitar strung up for a while to make sure you will not need to remove the neck for any adjustments. I have not glued a single bolt on neck yet and I have not had one issue. Thats the beauty of a bolt on. Ease of removal and adjustment down the road.
Keep up posted on your solution to this. It should be pretty easy.

Tony

[kencierp]

Common problem with bolt-ons from SM and LMII. Like already mentioned sand some material off the round end of the tenon the entire radius not just the bottom, you need to provide clearance all the way around. Also you need to elongate the holes in the neck block to provide clearance for the bolts. The KMG neck blocks are designed with slotted holes so slight misalignment is a not issue.

[Tony_in_NYC]

What Ken said! I meant to remove wood from the whole rounded end of the tenon but sometimes I am not so good at explaining myself.

[johnnparchem]

From his description he sanded the down the neck block to far while over sanding the top rim to fix his radius. I believe in the picture he is aligned with the pre drilled bolt holes; he can still slide the neck on properly but the bolt holes do not align.

I would either drill the holes in the block out a thirty-second wider or go at the holes with a rattail file until they align with the neck properly positioned. Filling the holes and re-drilling might be a cleaner solution.

He will also need to drill the pre-drill truss rod access hole bigger to get access to the truss rod.