Australian/New Zealand Luthiers Forum

The only two true Mahoganies I'm aware of are Honduran and Cuban. There must be more, but there's lots of faux mahoganies which I assume the question concerns. I know Larrivee uses Khaya (African Mahogany?) with success for sometime now.

John, That looks great! How were you able to drop the main air that low? I'm primarily building with a Hauser plantilla and my air resonance is usually around 102 HZ and I would like to drop it some. Looking at Trevor's sensitivity analysis it looks like sound hole diameter and back stiffness are my...

OK, that makes sense. Usually I see the type of thing with a flat leveling device used under tension.
Thanks

I'm always confused when I see something like this. When we level frets under string tension aren't you removing any relief you had?
Thanks

Mark,
I pattern routed using a 1/8" slotting style router bit with a guide bearing from my binding set to get the right depth.
The style of bit I used is shown on this web page.
https://www.mlcswoodworking.com/shopsit ... _slot.html
Hope this helps.

Alan,
I just sent you a PM with an attached drawing.
Jim

Alan,
I think I have a drawing or model of a bridge I did a while back. See the photo below.
If you want, I can try to dig it up if you're interested.

Seems like I've read many articles in the GAL by Jim. He contributed greatly to our craft and is a sad loss indeed.

Good to see this again and Brian's videos, thanks for posting that Trevor. I curious if there would be any use in adding a Q calculation to one of the taps as done in Trevor's book. If so which one. Or can we just compare the stiffness and weight and get a similar kind of thing (I think so) ? Seems ...

Ouch, hopefully a new bridge is all that's required.
Sorry to see that John.

Rod, you may have problem with the Nomex as it'll really only flex in one direction. An Archtop may have gentle enough curvature that you'll get away with it using 3mm thick core. But, there's a product called "flex core" which is designed to flex in both directions. It has a different cell geometry...

Miguel,
Why is there not a strong peak for the main air frequency, does the paper rolled in the sound hole suppress it?

Miguel, I should of noticed earlier but I see you back is only clamped on with a few clamps. I think every will change/be more defined when it's glued on.

Miguel, While others are certainly better at deciphering this than me, I suspect if you were to take a tap spectrum you would see a very broad peak around the 202 mark, or perhaps a really narrow one that you just can't dial into with your frequency generator. I believe the first scenario is most li...

Quick update. Jim Kirby's code runs just fine in Scilab using their Matlab to Scilab translator function.
Scilab is a free Matlab like program for those who may want to give it try.

Thanks for the link John, I'll give it a whirl. I'll need to try it in Scilab.
Jim

John, nice job there! Did the trebles stay focused and clear when you drop the tops resonance to 180? I've been kind of afraid to go that low for fear of losing clarity. Probably a misconception on my part. Also, you make reference to a Matlab script you found here. If you could point me to it that'...

Congratulations Bob, you started a good thing with this forum. All the best in you future endeavors and good to hear you'll still around some.
Jim

I think this might of been captured somewhere above, but to be an effective industrial tool the part should cost less. I should be able to charge a higher hourly rate yet be able to sell the part for less due to the efficiency gain in my process. Think Martin and Taylor. Really great guitars for the...

Hey there neighbor!
I build in the mountains of Northern New Mexico and try to brace my tops around 35 - 40%. That seems to work well. I have to humidify my shop to get it there though. RH typically varies from 5% -25% in the fall and spring and jumps to 25 - 50% in the summer "monsoon" season.

True enough!

Thanks for posting that Mark, i's fun to see this stuff applied. I haven't used the weights in a guitar yet as the overall weight of the instrument kind of goes against my grain, but between this and the book I may have to give it a try.

That's great for a days work!

I think the problem there is that by adding the cf tow, it's adding weight and stiffening the braces. I'm guessing it stiffens by a significant amount as the tow is on the outside of the brace.
Probably a really good experiment though to see if it works out.

Brian says you can just tape the back on?

I've found Sitka that stiff before too (statically tested). If you'll notice your density is pretty high, stiffness and density track each other fairly well. That is as the density goes up so does the stiffness, usually.