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Is this chamfer something I need to try and correct? Or move on and learn? Although... not sure how I’d go about it ha


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You could still do it there with a small plane, I’ve done it that way. These days I get it close before installing the block and then finish it off after install. It just reduces a hump in the top there. For me that’s a pain point when leveling finish. If you don’t chamfer the block it’s more stiff there and level sanding gets affected.

If I understand what Ed is talking about.


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What could also really work well there is a flat micro plane. Would make quick work of it. Or a rasp, etc....


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I use a Veritas mini block plane for most of it and a chisel for the rest:)


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You and do a 45 degree champher with a router bit too.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Lordy. So kerf is a verb now?

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formerly known around here as burbank
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And kerfing has become a noun from a non-existent verb.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Where I used to work, we had an entire dept dedicated to it!

Makes sense to this fool:)


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I was wondering how long it would be before this came up again lol.

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Steve Smith
"Music is what feelings sound like"

Good morning Kerflings!
Has the Pro-verb-ial kerfing kerfuffle reared it's ugly head again?

Ed Bond mentioned a gap between the glued on back and the neck block if I am reading things right (I couldn't see the picture posted). If that is the case I would suggest that filling that space with a shim or by some other method would be a good idea. On some of the older (1800's) guitars I have worked on I've seen where the neck has rotated forward and taken the soundboard under the fretboard with it after the glue has failed and the back has come loose. As Ed mentioned the Spaniards built with a "footed" neck block to help combat this. The French and Germans didn't and these seem to fail the most this way.
Here is a picture of a German guitar that has had the top pulled back in place and reglued after failing in that fashion:

I use an average sized to slightly larger heel block with a bolt on butt joint. Now you all have me wondering if I should consider a larger foot print block. I just finished 2 12 fret guitars with 14 fret body length and forward shifted sound holes (and am making two more). On the Oish sixe, I passed the soundhole braces under the UTB into the heel block on. On the parlor size, I was able to get the UTB butted right up to the heel block. Both of these were to hopefully reduce the change in box geometry over time.

I didn't really think about the back flattening out. How much surface area are you all using on the back side of your heel blocks to combat this?

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

What is in question is:
On the TOP I normally cut the tail block back so that the glue surface is the same width as the kerfing in order to avoid the block telegraphing through.
On this one I did the same on the neck block on the BACK in an uneducated attempt to free up a little more area to vibrate. There’s a solid glue surface the width of the kerfing all the way around.


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If you could replace it with a "normal" sized block that might be good to do. If that can't be readily done then fitting and gluing a piece between the neck block and back could also work. You could make it look intentional by extending it like a Spanish foot construction.
It may work fine as it is. With a strong UTB and the "popsicle" brace there is some resistance to the top pulling forward at the fretboard area. In any case I wouldn't expect it to be an immediate catastrophic failure.
The old designs often combine an economy of work and materials with strength and functionality, and the better ones get this balance right. Some of the new things tried fail over a relatively short amount of time, and the worst ones make the instrument virtually unrepairable.