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-   -   McKnight Guitars ... Shop Snippets '19 (https://www.acousticguitarforum.com/forums/showthread.php?t=545558)

Tim McKnight 05-03-2019 05:43 AM

A couple of days ago we ran out of kerfed linings. These are wood strips, with a series of evenly spaced saw cuts made in them, which allows the wood to be flexible enough to be easily bent. The waste area, which the saw blade removed wood from, is called the kerf and the wooden strip, which is glued to the inner side of the guitar, is called the lining so many people refer to these strips as kerfed lining. The lining ultimately provides a wider gluing surface area to which the top and back of the guitar will be glued to. IME kerfed lining provides no tonal benefit to the overall sound of the finished guitar. These are purely structural elements.

Some builders choose to make their linings from solid wood, some use thin strips of wood and then laminate them together. Some builders use reversed kerf linings orienting the kerf side toward the inside of the rim and some use "traditional" linings with the kerf cuts facing the inside of the guitar. Laminated linings are the stiffest and provide the most rigidity to the rim but add slightly more weight and mass, which I doubt amounts to a minuscule hill of beans in the end. We have used all of these types of linings and since we "generally" build with laminated or double sides, we use mostly the traditional and triangular shaped kerfed linings.

With that said, this is how we make our linings starting with a solid piece of wood we profile to shape on the table saw. BTW, we have used Spanish Cedar. Mahogany, Basswood, Wild Black Cherry, Black Walnut, Hackberry and Butternut and have found no tonal advantage to any one particular wood species. Here is the blanks we start with:
https://lh3.googleusercontent.com/Hk...=w1204-h903-no




And an end view to show the profile of the blank. For this run we are using Spanish Cedar. We cut these blanks to 16" in overall length:
https://lh3.googleusercontent.com/JN...=w1204-h903-no









We stack 13 blanks on the bed of our CNC to cut the kerfed slots. Why 13? Because that is the maximum amount that our CNC bed will allow space for. We have done this same fabrication process on a table saw, band saw and even cut some by hand using a back saw and miter box jig. We now use our time efficient CNC to cut these which allows us more time to do other tasks in the shop, while the CNC works for us in the background.
https://lh3.googleusercontent.com/Qg...=w1204-h903-no









It takes an hour and a half to cut all the slots with a 1/16" diameter router bit. We could program the machine to cut the wood MUCH faster but then we risk breaking an expensive $25 carbide router bit or breaking the fragile pieces of wood. Don't ask how I figured the ultimate cutting speed out :eek:
https://lh3.googleusercontent.com/s4...=w1204-h903-no









After the kerfs or slots are cut we hand sand each strip to remove the fuzz left on the surface of the wood from the CNC :
https://lh3.googleusercontent.com/bG...g=w678-h903-no









The final step is the rip saw each strip in half which then yields two identical pieces of kerfed lining. It can take up to 64" of these strips to line a jumbo size guitar rim.

*** Safety Note *** I am just posing for this picture because I do NOT get my fingers this close a spinning saw blade. I use feather boards and push sticks to keep my fingers out of harms way.
https://lh3.googleusercontent.com/24...=w1204-h903-no









The finished products look like this:
https://lh3.googleusercontent.com/GN...w=w678-h903-no









We could make these kerfed linings one at a time as we need them for each guitar. But as mentioned earlier, most of the time is spent in setting up the machine or tool for the task. Therefore, when we make linings we make several hundred of them at a time, usually enough to last us for about two years. Its more efficient for us to run them in batches like this to minimize our machine set up time.

j. Kinnaird 05-03-2019 08:16 AM

Cool. What you are doing is creating a desire for a CnC machine. Thanks.

Guitars44me 05-03-2019 08:52 AM

These ARE cool...
 
Quote:

Originally Posted by j. Kinnaird (Post 6052981)
Cool. What you are doing is creating a desire for a CnC machine. Thanks.

Hey John. I can't tell any attributed difference in the tone on your 4. Some have solid lining and some kerfed. But I do like the appearance of the solid linings when I peek in the port! They just look spiffy to me.

Just sayin'

Tim, now you are set for the next couple years. Whee...

Cheers

Paul

cigarfan 05-03-2019 10:33 AM

What a fun and informative thread. Love it! :)

Tim McKnight 05-04-2019 04:51 PM

Quote:

Originally Posted by j. Kinnaird (Post 6052981)
Cool. What you are doing is creating a desire for a CnC machine. Thanks.

I can certainly help! Watch this shiny pendulum John, Tick, tock, tick, tock ... Your getting sleepy, very VERY sleepy and when you awake you will have an irresistible urge to add a CNC to your shop space...

j. Kinnaird 05-04-2019 08:15 PM

Quote:

Originally Posted by Tim McKnight (Post 6054187)
I can certainly help! Watch this shiny pendulum John, Tick, tock, tick, tock ... Your getting sleepy, very VERY sleepy and when you awake you will have an irresistible urge to add a CNC to your shop space...

Yep that did it. It’s official, I want one.

Are you the sales rep by any chance.

Bruce Sexauer 05-04-2019 08:52 PM

Very nice thread, Tim. Thanks for taking the time.

TomB'sox 05-04-2019 09:17 PM

There may be no tonal difference in what type of wood is used for the linings which are kerfed, but when it comes to the olfactory sense, I will chose Spanish Cedar please!!!

Tim McKnight 05-06-2019 05:33 AM

Quote:

Originally Posted by j. Kinnaird (Post 6054343)
Yep that did it. It’s official, I want one.

Are you the sales rep by any chance.

No, but I have been known to enable a time or two.



Quote:

Originally Posted by TomB'sox (Post 6054372)
There may be no tonal difference in what type of wood is used for the linings which are kerfed, but when it comes to the olfactory sense, I will chose Spanish Cedar please!!!

I couldn't agree more Tom. SC has a wonderful and intoxicating aroma.



Quote:

Originally Posted by Bruce Sexauer (Post 6054364)
Very nice thread, Tim. Thanks for taking the time.

I lurk on yours and many of the other builder threads here Bruce and I enjoy seeing how other builders approach similar tasks. There are lots of ways to arrive at the proverbial finish line.

Aura 05-06-2019 10:25 AM

Quote:

Originally Posted by Mary (Post 6050217)
I see this is your 7th post. Welcome to the AGF community where I have found the brotherhood of the luthiers a joy to be a part.

Thank you!

Thanks also for the update!!:up:

Tim McKnight 05-07-2019 05:59 AM

Quote:

Originally Posted by Aura (Post 6055475)
Thank you!
Thanks also for the update!!:up:

Welcome to the forum Aura and thanks for following along in our thread.


Quote:

Originally Posted by cigarfan (Post 6053091)
What a fun and informative thread. Love it! :)

Glad your following along too Dennis.


Quote:

Originally Posted by Guitars44me (Post 6053009)
Tim, now you are set for the next couple years. Whee...
Cheers
Paul

Hi Paul,
Yes, we should be set for linings for the next couple years ;)

https://lh3.googleusercontent.com/wM...=w1204-h903-no




https://lh3.googleusercontent.com/33...=w1204-h903-no

Rodger 05-07-2019 05:49 PM

Little known fact... a gross of kerfed linings is called a kerfuffle.

Tim McKnight 05-08-2019 04:57 PM

Quote:

Originally Posted by Rodger (Post 6056577)
Little known fact... a gross of kerfed linings is called a kerfuffle.

Good one Rodger. I about lost it when I read “kerfuffle” :roll:

Tim McKnight 05-09-2019 06:22 AM

We built our first true Parlor size guitar for the Artisan Show last month and I really liked the result of "Tottie", so much so that two more are currently on our bench now. One will have a more modern 14 fret Venetian cutaway:
https://lh3.googleusercontent.com/AP...A=w633-h843-no









And one will be a traditional historic 12 fret rendition. Both Totties are base priced East Indian Rosewood bodies with Western Red Cedar tops. They will both use single sides instead of our usual double sides in order to minimize weight and staying truer to the 1840's weight goal of 3 lbs, which we nailed on Tottie #1.
https://lh3.googleusercontent.com/xz...Q=w633-h843-no

Neil K Walk 05-09-2019 06:43 AM

Man oh man, this thread is making me impatient for the McJam. Can I come live in the shack for a month? I'm sure my wife and kids won't miss me! ;)


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