Search found 52 matches

by Jim watts
Sun Jul 08, 2018 3:33 am
Forum: Instrument Builders Forum
Topic: 8 String bocote falcate braced nylon string crossover guitar
Replies: 11
Views: 973

Re: 8 String bocote falcate braced nylon string crossover guitar

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...
by Jim watts
Mon May 14, 2018 11:27 am
Forum: Instrument Builders Forum
Topic: End of the week how to, how to fret skim
Replies: 12
Views: 1157

Re: End of the week how to, how to fret skim

OK, that makes sense. Usually I see the type of thing with a flat leveling device used under tension.
Thanks
by Jim watts
Mon May 14, 2018 7:51 am
Forum: Instrument Builders Forum
Topic: End of the week how to, how to fret skim
Replies: 12
Views: 1157

Re: End of the week how to, how to fret skim

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
by Jim watts
Wed May 02, 2018 1:37 pm
Forum: Instrument Builders Forum
Topic: Pinless Acoustic Bridge
Replies: 7
Views: 966

Re: Pinless Acoustic Bridge

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.
by Jim watts
Sun Apr 29, 2018 1:27 pm
Forum: Instrument Builders Forum
Topic: Pinless Acoustic Bridge
Replies: 7
Views: 966

Re: Pinless Acoustic Bridge

Alan,
I just sent you a PM with an attached drawing.
Jim
by Jim watts
Sat Apr 28, 2018 9:52 am
Forum: Instrument Builders Forum
Topic: Pinless Acoustic Bridge
Replies: 7
Views: 966

Re: Pinless Acoustic Bridge

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.
2008_0124bridge0005.jpg
2008_0124bridge0005.jpg (114.05 KiB) Viewed 913 times
by Jim watts
Thu Apr 26, 2018 1:46 pm
Forum: Instrument Builders Forum
Topic: RIP Jim Williams
Replies: 4
Views: 868

Re: RIP Jim Williams

Seems like I've read many articles in the GAL by Jim. He contributed greatly to our craft and is a sad loss indeed.
by Jim watts
Thu Apr 26, 2018 12:46 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Measuring top and back frequencies while voicing
Replies: 21
Views: 7446

Re: Measuring top and back frequencies while voicing

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 ...
by Jim watts
Fri Sep 08, 2017 2:48 pm
Forum: Instrument Builders Forum
Topic: Completely traditional looking Hauser style classical guitar
Replies: 45
Views: 13314

Re: Completely traditional looking Hauser style classical guitar

Ouch, hopefully a new bridge is all that's required.
Sorry to see that John.
by Jim watts
Sat Sep 02, 2017 1:29 pm
Forum: Instrument Builders Forum
Topic: laminated plates
Replies: 12
Views: 2728

Re: laminated plates

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...
by Jim watts
Sat Jul 29, 2017 9:07 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: I lost the monopole...
Replies: 20
Views: 6959

Re: I lost the monopole...

Miguel,
Why is there not a strong peak for the main air frequency, does the paper rolled in the sound hole suppress it?
by Jim watts
Sat Jul 29, 2017 5:39 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: I lost the monopole...
Replies: 20
Views: 6959

Re: I lost the monopole...

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.
by Jim watts
Thu Jul 27, 2017 2:51 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: I lost the monopole...
Replies: 20
Views: 6959

Re: I lost the monopole...

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...
by Jim watts
Sat Jul 01, 2017 1:47 pm
Forum: Instrument Builders Forum
Topic: Retopping first Falcate braced Classical Guitar
Replies: 22
Views: 5867

Re: Retopping first Falcate braced Classical Guitar

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.
by Jim watts
Tue Jun 27, 2017 2:14 pm
Forum: Instrument Builders Forum
Topic: Retopping first Falcate braced Classical Guitar
Replies: 22
Views: 5867

Re: Retopping first Falcate braced Classical Guitar

Thanks for the link John, I'll give it a whirl. I'll need to try it in Scilab.
Jim
by Jim watts
Mon Jun 26, 2017 10:41 am
Forum: Instrument Builders Forum
Topic: Retopping first Falcate braced Classical Guitar
Replies: 22
Views: 5867

Re: Retopping first Falcate braced Classical Guitar

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'...
by Jim watts
Thu Jun 22, 2017 12:55 pm
Forum: Instrument Builders Forum
Topic: I'm retiring
Replies: 45
Views: 12688

Re: I'm retiring

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
by Jim watts
Mon May 22, 2017 1:54 pm
Forum: Instrument Builders Forum
Topic: Charging more for cnc work
Replies: 7
Views: 2048

Re: Charging more for cnc work

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...
by Jim watts
Thu Mar 23, 2017 12:30 pm
Forum: Instrument Builders Forum
Topic: Dry Climate Build Schedule
Replies: 21
Views: 4585

Re: Dry Climate Build Schedule

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.
by Jim watts
Mon Mar 20, 2017 6:59 am
Forum: Instrument Builders Forum
Topic: Adjusting sound
Replies: 38
Views: 8317

Re: Adjusting sound

True enough!
by Jim watts
Sun Mar 19, 2017 3:19 pm
Forum: Instrument Builders Forum
Topic: Adjusting sound
Replies: 38
Views: 8317

Re: Adjusting sound

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.
by Jim watts
Thu Nov 10, 2016 3:04 pm
Forum: Instrument Builders Forum
Topic: Most recent build
Replies: 16
Views: 4950

Re: Most recent build

That's great for a days work!
by Jim watts
Sun Jun 26, 2016 5:38 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Measuring top and back frequencies while voicing
Replies: 21
Views: 7446

Re: Measuring top and back frequencies while voicing

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?
by Jim watts
Tue May 31, 2016 6:36 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Suspiciously high Youngs Modulus
Replies: 4
Views: 1922

Re: Suspiciously high Youngs Modulus

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.
by Jim watts
Sat Dec 12, 2015 11:37 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: recently closed box
Replies: 4
Views: 1516

Re: recently closed box

Thanks for the reply Trevor. I think I'll get strings on it in the next couple of days and see how it sounds.