Neck joint misfit

erich@muttcrew.net

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I know this has been disussed before but searching didn't bring up what I was looking for.

We're working on a mezzo soprano (slightly larger soprano body with concert scale and neck length). The top, back and sides are ready to be assembled and the neck is practically finished. Now comes the problem. No matter how I tried yesterday I couln't get the neck and body to fit together exactly right. There's always a little gap here or there. I said to Matt some time ago it was good to go concave and then sand the side bits back down until you hit home. Well, sorry - easier said than done.

I can't post any pics at the moment but basically there's about 20mm in the middle of the joint that need to be almostflat and 10mm on each side that are very slightly curved. I think I remember someone reporting that you could press the two parts together, clamp them down and then pull a piece of sandpaper between them - but I would have to read the description again to get it right and I couldn't find it.

Anyone have a suggestion for us on how to get the neck and body fitting exactly snug?
 
"I said to Matt some time ago it was good to go concave and then sand the side bits back down until you hit home." You don't need to hit home. Leave it open in the middle, with 1/8" left on the sides, including the heel (I actually leave about 1/4" on the heel, because I'm afraid I'm going to run my dremel right over the edge and screw up the outside). Also, softer woods work better. Cherry is a real bear, sycamore a veritable kitten in comparison, and the genuine mahogany I'm working with currently, somewhere in between.
 
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Thanks, Matt.

The neck just happens to be (European) cherry with a (European) walnut skunkstripe. A real PITA, but it does look nice. One of the problems with this neck has been that there are a number of knobs in the cherry that are hard as... One of them is right at the throat and really has prevented me from getting the throat shaped exactly the way we want it.

Leave it open in the middle, with 1/8" left on the sides, including the heel ...

I'm assuming you mean a bolt on joint? If so, I think that would work - with a glued joint, maybe not.
 
You're doing a glued butt joint? I wonder if that will hold up
Can you make the top of the uke flat all the way across the neck joint?
 
Erich, I have had good luck using self stick sand paper and doing a rub joint. In your case, put the sand paper on the end of the body and slide the neck straight up and down. Matt's idea of using a Dremel to relieve the center of the neck slightly is a good one.

Brad
 
Erich, I have had good luck using self stick sand paper and doing a rub joint. In your case, put the sand paper on the end of the body and slide the neck straight up and down. Matt's idea of using a Dremel to relieve the center of the neck slightly is a good one.

Brad

That's exactly what I've done on the last two, and it works. Thanks to those who showed me the way.
 
Thanks, Matt.

The neck just happens to be (European) cherry with a (European) walnut skunkstripe. A real PITA, but it does look nice. One of the problems with this neck has been that there are a number of knobs in the cherry that are hard as... One of them is right at the throat and really has prevented me from getting the throat shaped exactly the way we want it.

I'm assuming you mean a bolt on joint? If so, I think that would work - with a glued joint, maybe not.

I put a bolt near the top of the neck (just under the fretboard) and then a little glue on those edges and heel, and then I clamp the heel after I've bolted on the neck. No gap!
 
You're doing a glued butt joint? I wonder if that will hold up
Can you make the top of the uke flat all the way across the neck joint?

Sorry I haven't responded to your suggestion but I must admit I just hadn't figured out exactly what you meant - now I think I've got it?

From a design point of view I think a little curve at the top of the soprano body looks better, but that's not the main issue. The problem we have now is that the neck block has been curved slightly on each side to match, so if we wanted to "make the [body] flat all the way across the neck joint" that would mean pulling the neck block out and putting a flat one in, etc. etc. Before we even think about going that route I'd say we should try the dremel + sandpaper method as suggested by Matt and Brad.

Thanks for your suggestions, everyone. I won't be back home until Friday, so please bear with me.
 
My amateur point of view:
Chalk. is what I was taught. Rub some chalk on the end of the body. Rub the neck against the body. Remove the chalk marks on the end of the neck with a sharp chisel. repeat etc. When you get close, then use sandpaper. Sometimes the slower you work the sooner you finish.

Neck fitting takes time.

Head strap magnifiers are a great tool.

I think next time I build a ukulele I will try to build with the top & neck on a "work board" and fit the sides into a bolt-on neck and block. The only disadvantage that I can think of is the glue "squeeze out" when the back is glued on.
 
Here's my jigs. They'll probably evolve a bit down the road, such as a centerline finder at just below the nut for the neck to body jig.
 
When I build tenors on my similar work board, I put two small brads in the necks centerline, on the fretboard side. The heads of the brads fit snugly in a small groove routed in the work board. So every time I put the neck down, it's automagically straight. Brads are removed before fretboard is glued, of course.

Sven
 
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