Official Luthiers Forum! :: View topic - Decided to rekerf the top

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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Lordy. So kerf is a verb now? [headinwall]

Pat Foster wrote:

Lordy. So kerf is a verb now? [headinwall]

And kerfing has become a noun from a non-existent verb.

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:

Author:	SnowManSnow [ Wed Jul 24, 2019 12:29 pm ]
Post subject:	Re: Decided to rekerf the top
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 Sent from my iPhone using Tapatalk

Author:	bcombs510 [ Wed Jul 24, 2019 12:39 pm ]
Post subject:	Decided to rekerf the top
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. Sent from my iPhone using Tapatalk Pro

Author:	bcombs510 [ Wed Jul 24, 2019 12:41 pm ]
Post subject:	Re: Decided to rekerf the top
What could also really work well there is a flat micro plane. Would make quick work of it. Or a rasp, etc.... Sent from my iPhone using Tapatalk Pro

Author:	SnowManSnow [ Wed Jul 24, 2019 2:21 pm ]
Post subject:	Decided to rekerf the top
bcombs510 wrote: 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. Sent from my iPhone using Tapatalk Pro I use a Veritas mini block plane for most of it and a chisel for the rest:) Sent from my iPhone using Tapatalk

Author:	Colin North [ Wed Jul 24, 2019 4:15 pm ]
Post subject:	Re: Decided to rekerf the top
You and do a 45 degree champher with a router bit too.

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Author:	Pat Foster [ Wed Jul 24, 2019 7:16 pm ]
Post subject:	Re: Decided to rekerf the top
Lordy. So kerf is a verb now?

Author:	J De Rocher [ Wed Jul 24, 2019 7:50 pm ]
Post subject:	Re: Decided to rekerf the top
Pat Foster wrote: Lordy. So kerf is a verb now? And kerfing has become a noun from a non-existent verb.

Author:	meddlingfool [ Wed Jul 24, 2019 8:48 pm ]
Post subject:	Re: Decided to rekerf the top
Where I used to work, we had an entire dept dedicated to it!

Author:	SnowManSnow [ Wed Jul 24, 2019 8:50 pm ]
Post subject:	Re: Decided to rekerf the top
Pat Foster wrote: Lordy. So kerf is a verb now? Makes sense to this fool:) Sent from my iPhone using Tapatalk

Author:	SteveSmith [ Thu Jul 25, 2019 6:45 am ]
Post subject:	Re: Decided to rekerf the top
J De Rocher wrote: Pat Foster wrote: Lordy. So kerf is a verb now? And kerfing has become a noun from a non-existent verb. I was wondering how long it would be before this came up again lol.

Author:	Clay S. [ Thu Jul 25, 2019 7:47 am ]
Post subject:	Re: Decided to rekerf the top
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:

Author:	Bryan Bear [ Thu Jul 25, 2019 7:57 am ]
Post subject:	Re: Decided to rekerf the top
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?

Author:	SnowManSnow [ Thu Jul 25, 2019 8:19 am ]
Post subject:	Re: Decided to rekerf the top
Clay S. wrote: 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: 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. Sent from my iPhone using Tapatalk

Author:	Clay S. [ Thu Jul 25, 2019 9:24 am ]
Post subject:	Re: Decided to rekerf the top
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.

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