Search found 545 matches

by johnparchem
Mon Mar 25, 2024 2:28 am
Forum: Instrument Builders Forum
Topic: Bridge routing - crisis and opportunity
Replies: 3
Views: 137

Re: Bridge routing - crisis and opportunity

I cannot see the fix. Along the grain I generally use super glue to glue in patch, finishing with rerouting the slot. I have lots of practice fixing these types of issues.
by johnparchem
Tue Mar 19, 2024 2:09 am
Forum: Instrument Builders Forum
Topic: Carbon Fibre Threads
Replies: 5
Views: 320

Re: Carbon Fibre Threads

Just looking at your numbers, and I think you get this, Looking at the addition of mass replacing 1g of wood, in my experiment above, with 1g of Carbon Fibre / Epoxy is a red herring, rather look at the deflection 27 to 20. a giant change in the deflection thus stiffness using a material that does n...
by johnparchem
Sun Feb 25, 2024 6:40 am
Forum: Instrument Builders Forum
Topic: Modal Tuning with Trevor Gore Question
Replies: 2
Views: 2100

Re: Modal Tuning with Trevor Gore Question

I took Trevor's model tuning class after reading The Book and incorporating much of what I had learned into my build process. I also at the time I took the class had built a lot of guitars with the processes I developed after reading The Book. I found the class very rewarding. It was well structured...
by johnparchem
Fri Dec 08, 2023 12:50 am
Forum: Instrument Builders Forum
Topic: Cross grain classical soundboard bracing
Replies: 3
Views: 5529

Re: Cross grain classical soundboard bracing

I found that the bridge itself is a very stiff cross grain brace of the lower bout in a classical guitar. My classical guitars are falcate braced without a lower transverse brace. I get a 10 Hz rise in the top resonance frequency when I glue on the bridge. I get a drop on my X braced steel string gu...
by johnparchem
Sat Sep 23, 2023 4:49 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Nodes and anti-nodes
Replies: 7
Views: 25886

Re: Nodes and anti-nodes

Barry Daniels wrote:
Sat Sep 23, 2023 3:22 am
I put a layer of cheese on my current build but it did not tell me anything. What did I do wrong?
You need the microwave amplifier for your Chladni patterns.
by johnparchem
Sat Jul 29, 2023 8:22 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Nodes and anti-nodes
Replies: 7
Views: 25886

Re: Nodes and anti-nodes

sounds right to me nodes are points of no displacement vs antinodes where the most displacement is.
by johnparchem
Mon Jul 17, 2023 12:29 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Testing Pacific Rim Tonewoods sonic graded tops
Replies: 2
Views: 9165

Testing Pacific Rim Tonewoods sonic graded tops

I am starting a new classical guitar. At the Guild of American Luthier convention I bought some Pacific Rim Tonewoods sonic graded tops with the Density and young modulus and Q provided. How well do they match up? Actually pretty well: Density 422 kg/m3 vs 411 and elong of 13.67 GPa vs 13.8 GPa. Whe...
by johnparchem
Sat Jul 15, 2023 7:48 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: neoclassical falcate braced guitar as per t gore
Replies: 1
Views: 8410

Re: neoclassical falcate braced guitar as per t gore

I have made a handful of falcate classical guitars. Never as large as a Dreadnought. First question I would have is will you have a lower transverse brace? I do not. If you do not have a lower transverse brace and you have a thinner classical top than your steel strings the falcate braces should be ...
by johnparchem
Wed Jul 05, 2023 9:48 am
Forum: Instrument Builders Forum
Topic: Trouble Build
Replies: 20
Views: 140872

Re: Trouble Build

Those are fairly nasty looking VA plots, Martin. Lots of background noise or something else going on? I'm running mic output into laptop via a preamp....might have something to do with the background noise. Ive also got smoothing turned off. Guitar was lying on its side with neck on a neck rest so ...
by johnparchem
Tue Jul 04, 2023 12:27 pm
Forum: Instrument Builders Forum
Topic: Trouble Build
Replies: 20
Views: 140872

Re: Trouble Build

Just throwing mud against the wall ... I build both slot head classical guitars and guitars with peg tuners. The headstock angle on my slot heads are 9-10° but I use 15° on the guitars that I use pegs to tune as they terminate the string higher. Headstock/neck angle is 15degrees. Strings leave the ...
by johnparchem
Tue Jul 04, 2023 11:15 am
Forum: Instrument Builders Forum
Topic: Trouble Build
Replies: 20
Views: 140872

Re: Trouble Build

Just throwing mud against the wall ... I build both slot head classical guitars and guitars with peg tuners. The headstock angle on my slot heads are 9-10° but I use 15° on the guitars that I use pegs to tune as they terminate the string higher.
by johnparchem
Tue Jul 04, 2023 2:18 am
Forum: Instrument Builders Forum
Topic: Trouble Build
Replies: 20
Views: 140872

Re: Trouble Build

Weird, did you check for loose components on the tuning machine? I assume you checked the nut as well? I sometimes temporarily lift the strings with tape at the nut to see if the sound goes away.
by johnparchem
Fri Aug 19, 2022 1:51 pm
Forum: Instrument Builders Forum
Topic: X Bracing planning
Replies: 6
Views: 5475

Re: X Bracing planning

I decide how close I want the X to the sound hole and then I make sure I clip the wings of the bridge. Extending the the lines place the ends of the braces.
by johnparchem
Sun Jul 24, 2022 11:29 pm
Forum: Instrument Builders Forum
Topic: Elvis has entered the building
Replies: 9
Views: 10101

Re: Elvis has entered the building

Thank you, Thank you very much
by johnparchem
Mon Mar 28, 2022 2:25 pm
Forum: Instrument Builders Forum
Topic: new classical with spectrum
Replies: 8
Views: 7477

Re: new classical with spectrum

Very nice guitar! I really like the guitars I made pitched around 190 Hz for the top. I love how the headstock joint worked out.
by johnparchem
Wed Feb 02, 2022 10:45 am
Forum: Instrument Builders Forum
Topic: Elmer Guitar
Replies: 10
Views: 15331

Re: Elmer Guitar

I see the prices but it does bother me that they are knockoffs of stewmac products as opposed to functional equivalent products. Maybe they are OK quality, China has very good manufacturing but if not held to a testable specification the quality of the materials and fit and finish goes down.
by johnparchem
Wed Jan 26, 2022 3:45 am
Forum: Instrument Builders Forum
Topic: This will wind a few up….
Replies: 7
Views: 7697

Re: This will wind a few up….

I made the mistake making a comment once on electric guitars on a different forum, never again just not worth it. My comments only involved the the sound difference between a EIR fretboard vs ebony.
by johnparchem
Thu Nov 18, 2021 4:22 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Air, Top and Back Resonances, Coupled and Uncoupled - Untensioned?
Replies: 17
Views: 41047

Re: Air, Top and Back Resonances, Coupled and Uncoupled - Untensioned?

Stiffness does not change with load. Stiffness is a constant. Deflection changes with load. Are we sure on that? Yes, load first causes deflection, which changes the location of the neutral axis in a beam (towards the fibers under compression), which I think we can presume happens with the soundboa...
by johnparchem
Wed Nov 17, 2021 11:57 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Air, Top and Back Resonances, Coupled and Uncoupled - Untensioned?
Replies: 17
Views: 41047

Re: Air, Top and Back Resonances, Coupled and Uncoupled - Untensioned?

... I do check the resonances before I finish and glue on the bridge. This lets me know that I am in the range. At that point the only remediation I would do is thin the edges of the top if I think the resonances are too high. Hi John Thanks for your thoughts. Do you find the initial untensioned to...
by johnparchem
Wed Nov 17, 2021 2:45 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Air, Top and Back Resonances, Coupled and Uncoupled - Untensioned?
Replies: 17
Views: 41047

Re: Air, Top and Back Resonances, Coupled and Uncoupled - Untensioned?

On a closed and bound guitar I have tried taping on the bridge and just adding mass with Blue tac neither really told me much. The bridge is also a brace stiffening the top; that is lost with taping and just adding mass. On repeat guitars I am consistent enough that I have a pretty good knowledge ab...
by johnparchem
Thu Nov 11, 2021 2:27 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Target Plate Thickness for 0/Parlor Guitars
Replies: 7
Views: 18120

Re: Target Plate Thickness for 0/Parlor Guitars

The smallest I have gone is falcate braces on a 00 body. In terms of the calculated thickness, I suspect there is a minimum thickness required for falcate or x braced guitar for the structural requirements. I retopped (a dropped) lattice braced guitar with a top around 1 mm. The lattice distributed ...
by johnparchem
Sat Oct 30, 2021 2:36 pm
Forum: Instrument Builders Forum
Topic: Neck Taper
Replies: 16
Views: 22934

Re: Neck Taper

I use a safe-t planer on a pillar drill. I get the taper by calculating A nut side shim the I attach to the finger board side of the neck. The Book shows using a Safe-T plane as well but the neck fits into a jig with the correct taper. I just did this for a concert ukulele I shim up the nut side of ...
by johnparchem
Mon Oct 25, 2021 8:51 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Tuning Components Off Note or On?
Replies: 5
Views: 14186

Re: Tuning Components Off Note or On?

I agree, I read Rodger Siminoff book at it made little sense to me. He advocated individually tuning each brace to specific notes. I could not understand how those tones meant anything once the brace is glued down. I got a DVD in my book and he contradicted half of what he said in the book. I am sur...
by johnparchem
Sun Oct 17, 2021 1:43 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Puzzled re adding mass etc…
Replies: 5
Views: 16637

Re: Puzzled re adding mass etc…

John Thanks a lot for the reply. I will take your advice and check when strung up. I thought it was to be tested without strings on but as I said it’s my first time to try side mass so I will wait. Can I assume with those figures that you would be trying to get the 178 down to 170?? Dave It depends...