Official Luthiers Forum!

My entry is going to be a bit of an experiment. I am going to build an OLF-SJ size/shape guitar that has a "triple top" (sitka/sitka/sitka with a laser-cut honeycombed center) made from 3 of Shane's 2A specials. The back and sides will be local claro walnut.

I will post photos and build progress reports periodically.

Cheers
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Wow..will be watch'in this one with great intrest Dave...go get'em

Cheers

Kim

curious to know why?
no bracing?

Thanks Kim!

Steve - it's the asymtote of increasing the soundboard stiffness while reducing the bracing size (yes, no bracing)....the honeycomb laminated triple-top came out more than stiff enough, and is much lighter than a "standard" top with my normal fair-curved X-bracing. All being well, this guitar could end up sounding great (or completely horrible)....we'll see....

The honeycomb center section of the top:


The finished top (notice the runout...but at $10 a top, I can't complain!):


The edge of the top, showing the three layers:


The claro walnut back/sides slab prior to jointing and resawing:


The sides being resawed:


I got 4 guitars worth of lovely flame/figured back and sides sets out of the slab, plus a lot of spare (good for boxes, pens, etc.):


Cheers for now,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Dave...very interesting. I built a double top last year and often thought about doing something similar to what you are doing. What are the thicknesses of the triple top layers?

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Brad
Avon, OH

That's some slick work there!

How long did that thing take to laser out and what method did you use to join the laminates?

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Brad - the center honeycomb piece is 0.085" thick, and the two outer pieces are 0.065" thick, for a total thickness of 0.215"....right now, that is.....I plan on thinning it a bit once the box is closed (especially around the edges), depending on how it taps and the deflection I see at the brige. The glued-up soundboard is 0.25" over-size all the way around (gotta leave some for routing after the top is glued to the sides) - this is quite a lot of extra weight that is going to disappear. If the technique works, I will build more instruments the same way and experiment with the stiffness to weight ratio in a more scientific manner.

Bob - I found that vector cutting didn't really work very well, the probem being that the little hexagonal pieces don't just fall out, but get in the way and cause cut errors (the vector grid stops many of them, but others seem to pop up and get in the cutting field. I ended up raster engraving it (using 100% power at a fairly slow speed). It takes many hours to do....I'm running one right now - it's been going for 2 hours and it's only just getting up to the wide part of the lower bout (it started at the bottom of the guitar = bottom-up engraving)....it's probably going to be another 3 hours yet! I'm going to try vector cutting the next one but with it raised up on a bed of strategically placed pins - should be about 30-40 minutes. That way, the little hexagons should fall out the bottom as they are cut and not get in the way.....we'll see. I used ordinary LMI Luthier's Glue to glue the three pieces together. I used glue sparingly and rollered it out thin. I glued all three pieces together at once, using a 28' dish in a vacuum press. It seems to keep its shape nicely.

I've been trimming the bookmatched walnut back wood, jointing them, and gluing them together this afternoon.....piccies later.

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Dave, that honeycombed top is almost unbelievable. (But there it is, right before me eyes....)
Don't be slamming the shop doors with one of those lying around in its unglued state!
In fact, don't sneeze or even curse too loudly. Looks really fragile.

(I just know I'd break it right before glue up time.)

Steve

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From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

This is a very interesting Build . I am glad we have the build threads so that we can watch this one being built !!

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Very curious to hear the results on this one...