Cumpiano neck join

[mac007]

Hi,

Does anyone have any comment on whether the bolt holes in the neck block need to be slightly angled to accomodate the slight 1-1.5 degress angle on the neck heel and tenon?

Or is there enough play in the oversize holes to make finding the barrel threads in the tenon not so difficult?

I hope this makes sense- it refers to the bolt and tenon barrel nut system of attaching the neck to the body.

chrs

M

[kiwigeo]

If the bolt holes are larger than bolt diameter then you should have a little bit of wiggle room.

[Taffy Evans]

Hi, the slightly oversized bolt holes in the neck block allow me to easily find the neck heal inserts.
Taff

[mac007]

Thanks for the replies.

Taff- do you cut a slight angle on the tenon heel when cutting the tenon (with about 5 deg taper on the sides) or just cut them square and chisel the back angle to get the required geometry?

chees

M

[kiwigeo]

The cheeks of the tenon rest on the front of the guitar and dictate the neck angle. The back of the tenon plays no part in the neck angle and should clear the bottom of the mortise by a few mm. When doing test fits...chalk up the bottom of the mortise so you can see if the tenon is bottoming out in same. Sometimes if you're making large adjustments to neck rake part of the back of the tenon will bottom out in the mortise.

Make chalk your friend

[Taffy Evans]

Hi Mac007, I do not use a tenon, over the last 20 years or so I have bolted the neck heal flush with the sides. I have never had any issues with this method. I have a jig I use to determine the neck heal angle required, on the bench, then set up my sanding machine jig to recreate that on the neck blank. I would then bolt it to the body and fine-tune tune as required if necessary.
Cheers Taff

[mac007]

Thanks for the replies.

Yes Taff- I can see your point that the tenon isn't really doing much in a bolt on (unless your trying some Hendrix like manoevres) tho' Trevor G may disagree.
So why even glue the fingerboard to the top other than to provide support and prevent some distortion? You could use some short screws and appropriate washers through the top to anchor and connect the fingerboard. Archtops don't but they have a neck extension- but I digress!

Thanks Martin. I have some chalk and we will become better aquainted!

I did get trapped by that tenon 'bottoming' out on a jazz box build and kept removing cheeks-only to make it worse! Then a chippy dropped by with a chippy folding ruler and pointed out the problem.

As chippies do.

chrs

[kiwigeo]

I did get trapped by that tenon 'bottoming' out on a jazz box build and kept removing cheeks-only to make it worse!

Exactly how I discovered the issue!! It pays to measure up depth of mortise and length of tenon before you start so you know roughly how much of a gap you have between end of tenon and bottom of mortise to play with.

[Dave M]

Yes Martin!

[Taffy Evans]

Hi, yes that's an issue I keep in mind when re-setting necks on many different brands of guitars.
Taff