I just glued the neck onto an archtop I am building. The fit was perfect (using a thin shim) when dry fitting so I went ahead and glued it. When going back and looking at it after a couple of hours, there is a gap at the end cap (see pictures). The height at the saddle and the alignment down the center are still good, but the gap is very disappointing.
I am contemplating removing the neck and refitting. Is the process for removing an archtop neck (dovetail joint) the same as a flattop? ... Heat the glue under the neck extension and loosen with a thin spatula, remove the fret at the 15th fret, drill a small hole and steam the neck off while applying pressure in a removal jig (which I have). I have removed the necks on a number of flat tops so I have some experience, but I am not sure what to watch our for on an archtop neck removal. I am concerned about getting the glue hot enough to soften the yellow glue under the neck extension with the thickness of the neck there.
Or at this point should I just find something to fill the gap and leave the neck on? If so, please advise.
That's a huge gap. Maybe your shim slipped out? I would heat palette knives to loosen the tongue, and steam the joint as you described. Definitely re-fit the joint.
I suppose you could "Keep and eye on it" but it won't get any easier to take apart than it is now. Besides, I can't see any sign of strings on the guitar so if it isn't under tension yet you will most likely HAVE to do it again anyway. I assume from your post that you didn't take this apart to begin with but since you glued it together, you would have a better idea of the position of the joint than we will.
I'm one of the people that uses very thin hot knives to remove the finger board extensions which requires me to be very careful with the finish around the edges of the FB and the grain run out but means that I don't have to avoid cooking the top to get the extension loose. You might consider doing it that way.
It's a bit hard to tell in the pictures so forgive me if I'm off base but it appears to me that you may not have fit the edges of the heel to the body before you glued this up. At least the pictures seem to indicate that there is a fall off on each side of the heel and the line down the length of the heel doesn't look tight. If this is what happened, it could be that the dove tail fits tight but the edges of the heel need to be fit to the body a bit tighter.
To me, it appears in the pictures as if there's a dome or high spot in the binding under the heel cap. Perhaps that is the partial cause of this issue. It's just a guess.
Otherwise, it's a very well crafted build and deserving of whatever it takes to make that joint as well crafted as the rest of the instrument. Kudos.
Best of luck :)
I was think the same as Paul but don't know if it's an aberration in the pic...
I did get the joint apart and it appears a couple of things contributed to the problem. My shim did slip to the end of the mortise when putting the joint together and yes, there was a high spot on the surface of the body where the neck fit that I sanded flat after removing the neck. What I can't figure out is how I missed this one! It seemed to fit tightly before gluing! Maybe I need a new set of glasses!
Thanks Paul for your comment about being well crafted. I have really tried my best on this one. One thing for me to take mental notes on though and any suggestions would be appreciated. In heating the fingerboard extension to loosen the glue underneath, the plastic binding started to melt. It wasn't enough that I couldn't sand in flat again but there is a little area where the black/white purfling lines are not at crisp as a result. I am thinking I should have used a hot knife instead, especially where there was no finish involved or used no glue at all under the extension. I don't know for sure. Comments?