Australian/New Zealand Luthiers Forum

Trevor, I was wondering why you put the carbon fiber sheet between the bridge plate and the top plate, rather than on the outside of the bridge plate...seems like it would be helpful to increase the distance between the two layers of carbon fiber (ie: in the bridge sandwich)? Also, since in my case,...

Trevor,
Are you offering pdf plans for another size falcate-braced guitar...maybe a small size...that you have had good results from? If so, can you send me purchase information?
Thanks,
Ron Rapp
risky@arappco.com

If I trim back the fret board then my T(1,1)1 should increase...which would be a good thing if I don't land on 98 Hz (G)...maybe incremental trimming?

Martin, thanks for the response! Yes, I don't have enough material for a double bend...but maybe a sound hole curve...

John, thanks, I have been following your builds on Robbie's forum! Good work!

Very observant Martin!
I guess indecision got in the way...
I was planning on putting that fret in, but then started thinking about trimming the fretboard down, and ended up in no-man's land...
What would you do with it?
Thanks,
Ron

To follow up, the tap test for the finished guitar is shown below, along with some pictures...

I wanted to post an update on the finished guitar...Ron
BTW, I am very happy with the final sound!
Thank you Trevor for introducing me to this style of building.

Good question Martin, but I do not have a definitive answer for you...
The book had a passing mention of redwood bendability, but I did not see a stiffness comparison...
This MAY be an issue with the low frequency...

Thank You!
Ron Rapp

Thanks Trevor, Looks like it is back to ol' Section 4.11... As you can see from the picture, my epoxy/carbon fiber skills need work, but I think my wood fitting skills are reasonable... :) If you see any "Oh, THAT's the reason for the low frequency", please let me know... I know this subject is exce...

Hello Trevor,
I re-tapped the box with it in my lap, and attached is the resulting chart:
T(1,1)1 = 97
T(1,1)2 = 172
T(1,1)3 = 227

Thanks for looking into this again.
Ron Rapp

Trevor, Also, regarding the initial measurements of the Englemann top... F long (Hz) = 73 F cross (Hz) = 140 F diag (Hz) = 39 Mass, gms = 204.9 Length, mm = 568.325 Width, mm = 227 Thickness, mm = 4.6 Density, kg/m^3 =345.27 Elong, Gpa = 8.54 Ecross, Gpa = 0.8 G, Gpa = 0.5 Elong/Ecross = 10.7 Plate ...

Trevor, Thank you for the response! The only variance to the book design are the materials in the falcate braces: -The primary falcate braces are Englemann Spruce laminates using epoxy...maximum height of 9mm. -The secondary falcate braces are California Redwood laminates using epoxy...maximum heigh...

Hello Trevor! I just completed the "box" based upon the falcate design in your book. I am using an Englemann Spruce top with Sapele back and sides. Attached is the frequency spectrum. The main top T(1,1)2 appears to be quite a bit lower than expected in the design book... Can you take a look and tel...

Thank YOU!
The threads really helped...still not sure why the problem...must have been the Excel issue...Thanks again, Ron

The shear modulus calculation is correct in my Excel equation, but I still have issues with the thickness equation 4.5-7...I am using the a=.49m and b=.195m (half panel) box size that Trevor is using in Table 4.5-3, but the result shows 0.00894m thickness...???

I am having problems with either the shear modulus equation 4.5-4 or the thickness equation 4.5-7 when entering them into Excel...I have rechecked the equations multiple times, but my targeted panel thickness does not match those shown in Table 4.5-3... Has there been any "oh yeah" moments from anyo...