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I did a search but didn't find anything a definitive post. I'm working out of Guitarmaking by William Cumpiano and Jonathan Natelson. On page 48, under step 8 - Marking for the Heelblock,



Ok, so I have my line to mark the position of the 14th fret.From there I turned stupid. I made another line 1/8th of an inch towards the body. I used this line to glue up the back of the heel block. I should have made a line 15/16 of an inch, instead of 1/8. So I'm 13/16 of an inch off.

Is the best solution just to saw of the block at the glue joint and reglue? Would I be able to adjust the scale on the figureboard? Or, since this is my first, and using bottom of the barrel wood, and I'm planning immediately making another one, just role with the block being close to the body than it should? Could I adjust the length of the truss rod?



Pictures are worth a thousand words. From left to right the lines are, 14th fret, 1/8th of an inch south of that (where I glued the block.), and 15/16 of an inch south of the 14th fret. (where the block should be.)

Saw it off, clean up, re-glue.

About 5 minutes work. Then you're back on the program. Otherwise, you'll spend a lot longer than that figuring out all the changes/fixes you'll have to make to compensate.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

I'm a little confused as to what I'm looking at. Is that the headstock end on the left? If so, shouldn't the blocks be 15/16" of an inch from your 14 fret in the opposite direction from where you have your pencil line? Right now your 14th fret is just hovering in space with no heel underneath it. Or am I looking at the picture wrong?

The block should actually be starting further back towards the nut, not where you have it
The 15/16 measurement is where it finishes.

No you're looking at it correctly. I have no idea how I did that. But that makes it easier to fix, since I already trimmed the neck to the back of the block.

I feel at this point I must point out that while I'm obviously a novice luthier, I am an experience woodworker.

Just so you understand what's going on instead of just following measurements:

The neck meets the body at the 14th fret. The depth of the neck block mortise is 1". You want to be sure that the end of the tenon does NOT bottom out in the mortise, so you put the end of the heel block (i.e. what will become the end of the tenon) 15/16" past the 14th fret....15/16" past where the neck meets the body, ensuring that the tenon can never bottom out. In reality, it shouldn't bottom out anyway because the thickness of the sides are in the way, but a little sanding here, a little fitting there, and all of a sudden it doesn't fit anymore.

The heel block can extend towards the headstock as far as you wish, as any excess will be cut and carved away.