McKnight Walnut / LS Redwood Build thread

[mmmaak]

Originally Posted by Yamaha Junkie

Gee wiz buddy! You played the heck out of that Webber!

Tell me about it.. Look at the toll it took on my hands!

[SongwriterFan]

Here's some updated pics that Mary sent yesterday.

I'll let Tim explain what's going on here. I sorta feel like a guinea pig. (Though I think he's doing this to several, if not all, of his guitars for Healdsburg).

Start with this picture:

http://www.neonlightsimaging.com/McK...d/img_2041.htm

But for those too lazy to follow the link and see all the pics, I'll post the final result here (just because this is too cool):







Yeah, baby, we got carbon fiber in the McKnight!

[mmmaak]

Interesting....do those rods counteract the tendency of the string tension to stretch/deform the back?

Wonder when luthiers will start using carbon nanotube rods

That's a lot of pictures on the site. Who takes them? Mary?

[hnuuhiwa]

Looks similar to the buttress bracing that Greg uses on his Gwaltney builds. My understanding on Greg's builds is that he uses it for additional structural support as he also incorporates a cantilevered neck in the design. Since I don't think Tim is using a cantilevered neck, it will be interesting to hear what he has to say.

Originally Posted by mmmaak

Interesting....do those rods counteract the tendency of the string tension to stretch/deform the back?

Wonder when luthiers will start using carbon nanotube rods

That's a lot of pictures on the site. Who takes them? Mary?

[SongwriterFan]

Originally Posted by hnuuhiwa

Looks similar to the buttress bracing that Greg uses on his Gwaltney builds. My understanding on Greg's builds is that he uses it for additional structural support as he also incorporates a cantilevered neck in the design. Since I don't think Tim is using a cantilevered neck, it will be interesting to hear what he has to say.

No, Tim's not using a cantilevered neck.

But, yes, it does look very similar to what Greg's using in his guitars. Thanks for mentioning that. I wasn't aware of it.

If you go to this page, and look at the 16th picture in the slide-show, you'll see the similarities (and differences):

http://www.gwaltneyguitars.com/the_p...he_process.htm

Greg's using 4 tubes (one high and one low per side), compared to Tim's 2 tubes.

[hnuuhiwa]

Maybe it has to do with the hollow back design? I love it when builders develop these "different" things that get you thinking "hmmm, I wonder what that's for"...

O.K. Tim, inquiring minds want to know

Originally Posted by SongwriterFan

No, Tim's not using a cantilevered neck.

But, yes, it does look very similar to what Greg's using in his guitars. Thanks for mentioning that. I wasn't aware of it.

If you go to this page, and look at the 16th picture in the slide-show, you'll see the similarities (and differences):

http://www.gwaltneyguitars.com/the_p...he_process.htm

Greg's using 4 tubes (one high and one low per side), compared to Tim's 2 tubes.

[SongwriterFan]

Here's an even better picure of what Greg's doing with his guitars:



Hope Mark Kunkel doesn't mine me stealing this pic out of his build thread (that I just saw).

[SongwriterFan]

Also from Mark's thread . . . . looks like Ibanez is also doing something similar (but with wood instead of carbon fiber):

[Tim McKnight]

Welllllll .... Since you asked... I have a 12 string in this batch which got the creative juices flowing. My biggest fear, building 12 strings, is the added string tension and its affects on the top, back and more importantly the added risk of an impending neck reset down the road. I strive to build my guitars light, responsive and on the cusp of implosion. This added tension also adds to the risk of things moving around, especially in a 12 string design.

So I threw away all my previous design notions and set out to see if I could come up with a way to shift the neck torque to another, less venerable, area of the guitar. Knowing that any curved surface is inherently stiffer and stronger than any flat surface I put on my thinking cap and asked myself some design questions which led to the pictures you are viewing.

As the strings are drawn taught the neck is pulled upward by the string tension. In a conventional guitar design this torque is transferred mostly to the top which is loaded under compression and to the back which is being pulled in tension. In essence the top is trying to move inward while the back is trying to flatten out. The upper transverse brace, located above the sound hole, attempts to distribute this load into the sides. The arched back braces play a role to try to maintain the back arch and keep it from flattening due to the neck pull.

The problem with the design of most common upper transverse braces, the brace is at full height until it reaches near the ends where it tapers to near zero. In essence the brace is no stronger than the ends are tall so this is one reason why those designs can have issues with the sound holes sinking in.

If you examine architecture you quickly see that diagonal braces are used to make a structure stiffer and less prone to movement. If you view the guitar sound box from the side it is basically a rectangle.

All of the string torque is loaded into one end of the rectangle, because that is where the neck is attached. Therefore adding a diagonal brace to a rectangular box adds tremendous stiffness. The rectangle then is transformed into two triangular shapes which is one of the stiffest natural shapes used in design.

Without a top on my sound boxes I could easily deflect the neck block area by adding a slight amount of down force to the neck block extension. Once the top is glued on this stiffens up this area BUT it still can deflect over time. This deflection is what leads to higher action and the need to reset the neck many years down the road.

I decided to add two diagonal braces from the neck block down to the waist, which is one of the stiffest areas in the sound box. The torque of the neck is now transferred into the stiffest area of the sound box. Theoretically this should take the load from the top and back and distribute it. It should also remove the compression and tension for the top and back and therefore allow the top and back plates to vibrate more efficiently. Well at least that is my theory, at this point. The proof will be in the feedback that we get at Healdsburg

PS - I just posted this answer / explanation without having any knowledge of what Greg and Ibenez are doing. Notice, that I don't claim to be the first to use this design but I was only drawing from archetechtural design elements. Greg's design is pretty cool looking and I can see where it would add a great deal of rigidity to the soundbox. One of my design goals was to use the KISS method (Keep It Simple Stupid) which I think I have accomplished. This also coincides with another element of my design goals to keep the soundbox light and responsive.

[Mary]

Originally Posted by Tim McKnight

I am listening Kurt but my gut tells me otherwise.

Hang in there, Kurt. I ain't done with him, yet.

[Mary]

Originally Posted by mmmaak

That's a lot of pictures on the site. Who takes them? Mary?

Yepper - I take pictures so our customers will feel like they are here. I feel they should know exactly what they are spending their money on. Many of our customers, whom I prefer to call them or McKnight Guitar family, would never see the views of their guitar(s) this wife can get while her luthier husband is working.

Customers would be respectful of his space. As a wife, experience has taught me to know when to slip a camera in for a shot. I can shoot pictures as I am holding items, taping binding, designing another guitar, writing letters, reading, or... eating Christmas cookies.

Every Saturday, for several years, Tim and I have had breakfast in the shop. Many picnics lunches have been shared there so we can continue to work for our customers.

Most all of our evenings are spent in the wood shop, where the guitar music fills the air. Occasionally the music is broken by the planer, saw, drill, sander, etc... Tim has his side of the bench and I have mine.

With each step, each day, every minute, we are very well aware of where the camera is so McKnight customers don't lose a shot of knowing where Tim is in their build.

I haven't made a grand announcement at this point, but I am planning the 2009 McJam gathering in our wood shop. If you or and your friends are interested in joining us, Songwriterfan, Yamaha Junkie and a few others who have pre-signed up, please let me know.

We'd love to have you come by and spy on Songwriter's guitar build in the making!

[SongwriterFan]

Originally Posted by Mary

Hang in there, Kurt. I ain't done with him, yet.

So, are you pushing for an all-walnut first, or an all-koa?

[hnuuhiwa]

Originally Posted by Tim McKnight

Welllllll .... Since you asked... <snip> It should also remove the compression and tension for the top and back and therefore allow the top and back plates to vibrate more efficiently. Well at least that is my theory, at this point. The proof will be in the feedback that we get at Healdsburg

PS - I just posted this answer / explanation without having any knowledge of what Greg and Ibenez are doing. Notice, that I don't claim to be the first to use this design but I was only drawing from archetechtural design elements. Greg's design is pretty cool looking and I can see where it would add a great deal of rigidity to the soundbox. One of my design goals was to use the KISS method (Keep It Simple Stupid) which I think I have accomplished. This also coincides with another element of my design goals to keep the soundbox light and responsive.

Thanks for the explanation Tim...Lukas Brunner (Brunner Guitars) also uses internal butress bracing (using wood and not on the diagonal like yours) on his full size guitars. It supposedly enables him to design a braceles top that vibrates freely (very similar to what Ibanez is doing...he calls his a "Flying Top"), while retaining structural integrity since he also (like Greg) uses a cantilevered neck, so the fretboard extension is not helping to support the top as in "traditional" neck/fretboard construction.

Aloha,

Hen









But we digress... Sorry SWF, didn't mean to hijack your thread. Now back to the build...more pics please!

[Tim McKnight]

I have seen Lucas' design (only in pictures on the net) but our goals are different. His is targeted towards a braceless top, mine is targeted towards moving the string pull induced torque away from the top and back plates. In theory, mine should allow the top and back plates to react [differently] to string vibrations but time will tell in August I've been wrong before and have not been fond of eating crow ;(

[Kurt]

Originally Posted by SongwriterFan

So, are you pushing for an all-walnut first, or an all-koa?

I'm trying to put a bug in the back of Tim's mind for an all-walnut guitar from the 1700s Eastern black walnut his has stashed in good supply. That wood, when tapped, just rings forever -- it's amazing. But then again, so do rosewoods, right? And no one ever builds a rosewood-topped guitar. That said, I posed the possibility to Tim because I know that, even though he doesn't think it's a good idea, the possibility will fester in his mind until maybe, just maybe, he'll get one of his engineering-savant ideas about how to make it happen.

I've never played an all-koa guitar (and I'd be interested in your take if you have), but I have played a couple all-hog guitars and found them quite intriguing. That said, I'll likely end up with a cedar-topped guitar that will make far more sense for me. But it doesn't hurt to put a burr under Tim's saddle blanket once in awhile!