Search found 1604 matches

by Trevor Gore
Sun Jan 16, 2022 11:06 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Intonation Problem
Replies: 10
Views: 16007

Re: Intonation Problem

Check out that peak at ~440Hz. That's likely your problem...

In the 2nd Edition, Section 22.3.4 shows an example of how to fix this sort of problem on the 2nd partial (not in the 1st Edition). Also likley in the Modal Tuning Course notes.
by Trevor Gore
Fri Nov 26, 2021 8:16 am
Forum: Instrument Builders Forum
Topic: Schertier Slot Head Tuners
Replies: 5
Views: 4750

Re: Schertier Slot Head Tuners

I haven't used them either, but I would drill full depth at 6mm then open out for the collar with a metric step drill that has (at least) 6, 8 and 10mm steps. Picking up the original 6mm bore with the 6mm step should keep everything concentric. Best done with a pillar drill to keep the bores square ...
by Trevor Gore
Fri Nov 12, 2021 8:52 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Target Plate Thickness for 0/Parlor Guitars
Replies: 7
Views: 18124

Re: Target Plate Thickness for 0/Parlor Guitars

I measured 9 top plates today and calculated targeted thicknesses for 343 mm wide 0 guitars. Adirondack, Engelmann, Lutz and Sitka. I look a random 10% stiffness reduction considering the top width. If you're using the formulae in the books for the elastic constants, measuring them correctly and ap...
by Trevor Gore
Thu Aug 05, 2021 7:07 pm
Forum: Instrument Builders Forum
Topic: West systems GFlex or Titebond original
Replies: 2
Views: 3304

Re: West systems GFlex or Titebond original

If you're looking for a gap filling glue, avoid Titebond. The thinner the Titebond glue line, the stronger it is. I would also avoid liquid epoxies, which is what G/Flex appears to be. You need the glue to stay where you put it. So I would suggest using Techniqlue (an epoxy), which is thixotropic, s...
by Trevor Gore
Sun Aug 01, 2021 11:37 am
Forum: Instrument Builders Forum
Topic: Torrefied Tonewood
Replies: 24
Views: 27273

Re: Torrefied Tonewood

nkforster wrote:
Thu Jul 29, 2021 6:01 pm
Trevor may have tested this scientifically, but I've not.
No, I haven't done any objective tests.
by Trevor Gore
Fri Jul 09, 2021 12:31 pm
Forum: Instrument Builders Forum
Topic: How do you profile your bridge?
Replies: 10
Views: 7217

Re: How do you profile your bridge?

Page 20-8 in the Build book. Make a convex sanding form by either laminating veneers into the top dish that you used (then dress any spring-back by sanding in the dish) or just sand a block from scratch in the dish. I start with 80 grit and it never takes very long (no more than 5 minutes total) to ...
by Trevor Gore
Fri Jul 09, 2021 9:40 am
Forum: Instrument Builders Forum
Topic: New Gore Guitars website
Replies: 7
Views: 5323

Re: New Gore Guitars website

The UK is quite a low proportion of sales, which was a bit surprising as I know there is a lot of interest there. I think VAT and import duties really loaded up the price. The USA is a big market (no import tax/duties) and also Canada, which does have import taxes. There has been good interest acros...
by Trevor Gore
Wed Jul 07, 2021 7:56 am
Forum: Instrument Builders Forum
Topic: Falcate Bridge Plate Thickness
Replies: 6
Views: 4509

Re: Falcate Bridge Plate Thickness

1.5mm as per the second edition. Apologies for the typo that got through in the 1st edition.
by Trevor Gore
Thu Jul 01, 2021 9:12 pm
Forum: Instrument Builders Forum
Topic: New Gore Guitars website
Replies: 7
Views: 5323

New Gore Guitars website

When you've had a website up and running for a dozen or so years it can get quite big. I hadn't realised how much stuff I had there until I got a message from my hosting service saying they were going to switch off the content editor. That was about 6 months ago, so my website has been frozen in tim...
by Trevor Gore
Sat May 08, 2021 5:39 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Confused about frequency response in my first TG style falcate
Replies: 20
Views: 24947

Re: Confused about frequency response in my first TG style falcate

Nice guitar, Martin. Regarding the changing frequency responses, your early responses without the neck mean you couldn't have had strings on, and you may not have had saddle and bridge pins in. Just adding the mass of the strings can make quite a difference which people often put down to loading the...
by Trevor Gore
Tue Apr 27, 2021 9:55 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Bolt On Neck truss Rod
Replies: 3
Views: 5730

Re: Bolt On Neck truss Rod

I haven't found much info in the book regarding truss rod extension pocket for BO. :o !! Section 18.9.1 I wonder about where to place the adjuster nut Fig 18-7 Also when the fingerboard is finally glued down, how to stop glue entering the rod channel. Section 18.6, esp. 2 lines up from the bottom o...
by Trevor Gore
Tue Apr 20, 2021 1:02 pm
Forum: Instrument Builders Forum
Topic: detached bridge
Replies: 5
Views: 4735

Re: detached bridge

This may not be the only problem, but certainly looks like one of them... Looking at the thickness of the residual glue on the tail side of the detached bridge, that glue line looks way too thick, to the extent that the the joint looks like it wasn't properly closed. There could be numerous reasons ...
by Trevor Gore
Sat Apr 17, 2021 10:18 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: How useful is the CF under the brace?
Replies: 15
Views: 30542

Re: How useful is the CF under the brace?

Andos wrote:
Fri Apr 16, 2021 8:52 pm
...CF only has tensile strength, no compressive strength...
I think you need to re-check the theory of composite structures... Hint: the CF is held in a matrix...
by Trevor Gore
Fri Apr 16, 2021 9:57 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: How useful is the CF under the brace?
Replies: 15
Views: 30542

Re: How useful is the CF under the brace?

One of the main reasons for adding CF to the structure is to control cold creep, so it allows you to remove a lot of wood that would otherwise have to be there purely to keep the stress levels down so there is less cold creep. Over time, as wood creeps, only having one layer of CF will likely come b...
by Trevor Gore
Fri Apr 16, 2021 9:31 am
Forum: Instrument Builders Forum
Topic: Problem with side mass not changing T1
Replies: 2
Views: 2991

Re: Problem with side mass not changing T1

Moving down 17Hz would take an awful lot of side mass. The critical thing for making side mass work is to make sure the mass is so firmly connected that it is essentially integral to the sides, because to work the mass has to move precisely with the sides. So if the hold-down bolts aren't seriously ...
by Trevor Gore
Fri Apr 16, 2021 9:17 am
Forum: Instrument Builders Forum
Topic: Paulownia Acoustic Top
Replies: 10
Views: 8255

Re: Paulownia Acoustic Top

Paulownia has a similar range in long grain Young's modulus as King Billy, but typically is around 75% the density. As ever, it's critical to measure the piece of wood you are about to build with, but I can't see why Equ. 4.5-7 wouldn't work to tell you how thick to leave it.
by Trevor Gore
Sun Apr 11, 2021 9:51 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Specific mobility
Replies: 3
Views: 5548

Re: Specific mobility

The book says "Steel string guitars with monopole mobility greater than 14 x 10^-3 s/Kg are exceptional instruments indeed...." (p. 1-89) Note that in Fig 1.7-8 the guitars below 14 are all wood X-braced guitars and the one above 18 is falcate braced with CF. That tells you something about responsiv...
by Trevor Gore
Fri Apr 09, 2021 6:02 pm
Forum: Instrument Builders Forum
Topic: Finger pressure
Replies: 6
Views: 5476

Re: Finger pressure

If you have the 2nd edition of the books, check out Appendix V (not in Ed. 1) p. AV 2. You're probably better off measuring string displacement rather than pressure applied and p. AV 2 explains how to do this.
by Trevor Gore
Sat Apr 03, 2021 3:44 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Can you derive a freq plot from a sound clip?
Replies: 8
Views: 8993

Re: Can you derive a freq plot from a sound clip?

...And that got me thinking... can you use a high quality sound clip of an instrument and use it to figure out the freq plot?... As John Parchem has said, every played note contains an embedded impulse response. The best way I've found to derive a frequency response curve is to isolate a single not...
by Trevor Gore
Tue Mar 16, 2021 7:45 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Compenstaed nut jig
Replies: 7
Views: 8768

Re: Compenstaed nut jig

Trevor if by chance you read this I wonder what cutter you use? CMT 1/8" two flute solid carbide down spiral. A new one can be pretty aggressive, so I use ones passed down from other operations (e.g. rosette channel cutting). I run a low speed on Tusq, otherwise it melts. Bone could be run at a hig...
by Trevor Gore
Wed Mar 03, 2021 12:17 pm
Forum: Instrument Builders Forum
Topic: Airbrushing lacquer vs HVLP
Replies: 17
Views: 11797

Re: Airbrushing lacquer vs HVLP

I've sprayed lacquer with an airbrush, touching up the edges of fret boards. It works fine, but you need a big nozzle (for an air brush) and need to spray wet or the lacquer will dry before it hits the target. It's not the tool to use for a whole instrument, though. I've had an HVLP touch up gun (1....
by Trevor Gore
Sat Jan 30, 2021 10:18 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Intonation and Flamenco guitars
Replies: 4
Views: 5781

Re: Intonation and Flamenco guitars

This type of discussion can get very fraught very quickly. The outcome of the argument depends on what going-in assumptions you consciously and/or unconsciously make. Consider a couple of things: 1) Nut compensation works because it means you have to change the string tension (re-tune) to get the op...
by Trevor Gore
Mon Jan 18, 2021 9:12 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Plate target thickness of non rectangular plates using deflection testing
Replies: 11
Views: 15265

Re: Plate target thickness of non rectangular plates using deflection testing

It's not that hard to get the cross grain stiffness using deflection methods. The pics here are of my old deflection jig as they show the technique better. First the jig. Note that the support tubes themselves are longer than the panel is. DSCF6101s.jpg Here's the normal arrangement for measuring lo...