Cumpiano Neck Joint...anyone Try One?

[erikbojerik]

William Cumpiano's neck joint

I will probably try this with an archop project of mine (moving at glacial pace...). Cumpiano uses cross-dowels, but I've seen a couple of others that use threaded inserts.

Anyone tried this? Any opinions on whether the cross-dowels would be better/worse than threaded inserts?

[Myka Guitars]

I use threaded inserts on all of my acoustic guitars. The removeable aspect of this neck design makes it totally worth doing in my opinion. I haven't tried the dowels but they might be stronger. I actually drill a 1/2" hole through the heel of my acoustic necks and glue a dowel in so that the threaded inserts have some cross grain fibers to grab on to. Perhaps the metal dowels would eliminate the need for this. It looks like a great idea and you can't beat a straight tenon.

Here is what I do:

~David

[erikbojerik]

Thanks David, that's cool! I like the orientation of your dowel better than Cumpiano's, you can hide yours beneath the heel cap.

No access hole for the truss rod adjustment? Or is that neck pocket incomplete?

Also, what's up with those small black screws in the neck pocket and tenon?

[Myka Guitars]

The neck pocket is complete, truss rod adjustment is at the headstock. This makes neck construction much easier and you can adjust it without struggling through the soundhole. I also didn't want to drill through my braces.

What you are seeing at the end of the neck are the ends of the carbon fiber tubes and a piece of ebony to fill the remainder of the truss rod channel (could have been mahogany or anything really).

The neck block also has pieces of carbon fiber epoxied in to help hold the black together. It is a 3-piece design that I wanted to add support to. It is very strong and I can use less wood to make it (instead of one-piece). You can see the detail here:

I have more pictures if you need anything else.

[erikbojerik]

That's very neat, thanks David. I already have my neck block glued in, else I would have tried yours out. Maybe on the next one.

[KeithHowell]

I've used the cross dowells Cumpiano method. It works very well. I'm now trying to figure out a way I can use it in my ES335 style guitar I am currently working on. Does anyone have any suggestions.

Keith

[Myka Guitars]

Keith, do you have any pictures? It is hard to give advice about this until I can see what you have already. My only concern with the idea is that you will need a way to access the bolts. 335 style guitars are pretty thin and do not usually have space for it. I am not sure where you would put it.

[KeithHowell]

Keith, do you have any pictures? It is hard to give advice about this until I can see what you have already. My only concern with the idea is that you will need a way to access the bolts. 335 style guitars are pretty thin and do not usually have space for it. I am not sure where you would put it.

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I have the center block and am about to put the sides in place. I was thinking of accessing the neck bolts through the pickup route, but as you say these guitars are pretty thin and there's not much room. Perhaps I'll have to stay with the Gibson style glue joint, but if I can make a Cumpiano style bolt in work I would prefer that.

Keith