Search found 1337 matches

by Trevor Gore
Mon Sep 17, 2018 9:53 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Waterfall Spectrogram Program
Replies: 1
Views: 51

Re: Waterfall Spectrogram Program

I can't help you with phone apps, John, but the plots I did were made using Spectrum Lab on a PC. I think later versions of Visual Analyser also do waterfall plots, but not as flash looking as those in Spectrum Lab.

Any one else?
by Trevor Gore
Mon Sep 17, 2018 9:45 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Measuring beyond the decimal place for distances >600mm
Replies: 5
Views: 99

Re: Measuring beyond the decimal place for distances >600mm

I use a piece of 1/8" by 1/2" brass rod (Bunnings) that I machined to length on a milling machine with a good digital readout. It turned out to be 0.2mm short, but I just zero my calipers at +.2 to take care of that. If I was doing it without heavy machinery, I would likely just make a number of scr...
by Trevor Gore
Fri Sep 14, 2018 9:02 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Determining Panel Mass on Target Plat Thickness Chart
Replies: 1
Views: 81

Re: Determining Panel Mass on Target Plat Thickness Chart

The panel mass is the wood density multiplied by the panel volume. The panel volume is its thickness (which you have just calculated) multiplied by its area. The panel area is the bit that is hard to calculate. If the guitar shape was drawn on a CAD type program, the program will give you the area. ...
by Trevor Gore
Thu Sep 13, 2018 12:49 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: determination of soundboard flexural rigidity
Replies: 2
Views: 101

Re: determination of soundboard flexural rigidity

I don’t see how to calculate the neutral axis of the soundboard cross section in fig. 4.4-19. Take the moments of all the component areas about the base, setting up a large equation similar to the penultimate one on p 4-37. For calculating the x for the soundboard cross section do I have to take th...
by Trevor Gore
Thu Aug 23, 2018 2:24 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Rosette Router Jig
Replies: 5
Views: 414

Re: Rosette Router Jig

The hole in that bar is a through hole. The nuts and Belleville washers lock the threaded rod to that bar which screws in and out of the nuts on the wide bar, causing it to move. The piece of angle (NOT the bracket that had the gauge on) captures the sprung nut at the wide bar so that it does not ro...
by Trevor Gore
Sat Aug 18, 2018 1:08 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Rosette Router Jig
Replies: 5
Views: 414

Rosette Router Jig

Below, as per a request , a few photos of my precision router jig as used for rosettes. A few things go together to make this thing accurate. First, the large diameter pivot (10mm), the stiff structure of the thing, low runout after-market router collets on the DeWalt trimmer and the anti-backlash a...
by Trevor Gore
Sat Aug 18, 2018 12:25 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: NEW BUILD tap testing Englemann
Replies: 5
Views: 379

Re: NEW BUILD tap testing Englemann

The trip was very good, thanks. Was over with Robbie O'Brien doing the Modal Tuning Course a couple of times. Nice burst on that Gilet guitar! Just looking at the frequency responses can you tell if a particular piece is stiff across the grain, ie high Fc equals stiff piece of timber across the grai...
by Trevor Gore
Thu Aug 16, 2018 11:44 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: NEW BUILD tap testing Englemann
Replies: 5
Views: 379

Re: NEW BUILD tap testing Englemann

Any comment would be appreciated, some time since I did the course and had used the formula. Lower bout at 380mm is large for a 00 sized guitar. They are usually around classical size at 360-370mm. I recently measured one of Gerard's 00's at 370mm. I think CF Martin make them a little smaller than ...
by Trevor Gore
Thu Aug 16, 2018 11:36 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Carbon Fibre Thickness for Bridge
Replies: 1
Views: 123

Re: Carbon Fibre Thickness for Bridge

I am making a contemporary classical walnut bridge. I intend to use 2 layers of carbon fibre cloth which is .5mm thick - is this OK or does the cloth need to be thicker to give the correct amount of stiffness? The CF cloth as spec'd in the book (198gm/m2) measures up at ~0.27mm thick. Works fine. A...
by Trevor Gore
Thu Aug 16, 2018 11:18 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: First Falcate underway! Plate Thickness question?
Replies: 5
Views: 349

Re: First Falcate underway! Plate Thickness question?

For the Top plate, Trevor lists an f value of 75 to plug into the thickness calculation, but doesn't specify the bracing. For my bear claw sitka top, I get 3mm with an f value of 75, 2.8mm for 70, and 2.6 for 65. Should I use a lower value for falcate bracing? I use 75 with falcate bracing as per t...
by Trevor Gore
Wed Aug 15, 2018 7:21 pm
Forum: Instrument Builders Forum
Topic: J45 headstock design
Replies: 12
Views: 567

Re: J45 headstock design

Francis wrote:
Tue Aug 14, 2018 4:12 am
Not sure about the black 510's, I think the Cosmo version may suit better?
That's a great deco heastock. Shurely (!) it needs the Grover style deco tuners to match...(Other brands are available!!)

Image
by Trevor Gore
Tue Aug 07, 2018 1:11 am
Forum: The Gallery
Topic: Odd Ball Junior
Replies: 4
Views: 308

Re: Odd Ball Junior

Nigel, I hope that park bench isn't home these days.... :D

Nice job, BTW!
by Trevor Gore
Tue Aug 07, 2018 1:01 am
Forum: Instrument Builders Forum
Topic: Hard shellac touch ups - pale areas
Replies: 7
Views: 450

Re: Hard shellac touch ups - pale areas

If you sanded through to the wood, and took some "sun tan" out of the wood, the "sun tan" seems to take for ever to catch up, if it ever does. If you just sanded shellac, because all shellac has some tint to it, you have to match the thickness of coating pretty exactly in order to build to the same ...
by Trevor Gore
Thu Aug 02, 2018 1:10 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Further J45 questions
Replies: 12
Views: 788

Re: Further J45 questions

... I have golden shellac flakes but I've used bullseye (I think) shellac on a harp in the past. Is that a better bet for preventing tear out as it won’t colour the spruce?... I use either blonde or Platina, as those are the only two types of shellac I use. Neither of those colours the wood, but I ...
by Trevor Gore
Wed Aug 01, 2018 11:48 am
Forum: Instrument Builders Forum
Topic: Gidgee
Replies: 13
Views: 734

Re: Gidgee

Anyone used Gidgee for back and sides? For guitars, yes, a couple of times. Here's one. The other one looked much the same, but I left out the sap wood. Hard to bend the figured wood without leaving flats in it and very dense at ~1300kg/m^3. The straight grained wood planes fine, but the figured wo...
by Trevor Gore
Sun Jul 29, 2018 8:39 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Further J45 questions
Replies: 12
Views: 788

Re: Further J45 questions

One thing puzzles me though. The book indicates routing the binding then the purfling. If you use a ball bearing to dictate the depth and you do it that way around what does the bearing reference when cutting the purfling? I'm using the LMII router cutter rather than the Stewmac one. Originally, on...
by Trevor Gore
Fri Jul 20, 2018 5:46 pm
Forum: The Gallery
Topic: Indigenous themed retro SS and classical
Replies: 8
Views: 613

Re: Indigenous themed retro SS and classical

Thanks, all, for the kind words. What did you use for the inner ring material? It's palm. It came from the guy next door who had to take some trees down. Sorry, I don't know exactly what type of palm. I think all the trees that came down were the same, but there are lots of different colours availab...
by Trevor Gore
Thu Jul 19, 2018 11:40 pm
Forum: The Gallery
Topic: Indigenous themed retro SS and classical
Replies: 8
Views: 613

Indigenous themed retro SS and classical

I've not posted one for a while, so here's two! Both in blackwood and Lutz, both slot heads, both with an indigenous themed rosette. I tried Schallers on the SS after a twenty year holiday from the brand. Similar to Waverlys, but Gotohs will still remain my go-to tuners. The classical has an open po...
by Trevor Gore
Thu Jul 19, 2018 6:56 pm
Forum: The Gallery
Topic: 12 fret BRW small body
Replies: 22
Views: 6455

Re: 12 fret BRW small body

kiwigeo wrote:
Thu Jul 19, 2018 1:30 pm
Trevor, I assume the finish is hard shellac from Robert? You had no issues burning new shellac into the old finish?
This one was nitro all over, so no problems with drop fills.
by Trevor Gore
Wed Jul 18, 2018 9:36 pm
Forum: Instrument Builders Forum
Topic: Classical neck reinforcement. Yes or no?
Replies: 7
Views: 428

Re: Classical neck reinforcement. Yes or no?

It's worth looking at what might cause the various deformations of a neck over time. Broadly speaking, the direct loading is not much of an issue. Steel string guitars have smaller neck dimensions and higher string tensions and so the stress on a steel string neck is considerably higher. What is an ...
by Trevor Gore
Wed Jul 18, 2018 9:35 am
Forum: The Gallery
Topic: 12 fret BRW small body
Replies: 22
Views: 6455

Re: 12 fret BRW small body

I imagine it was falcate braced with CF so the top probably didn't move much but I wonder if it continued to compress a little? Did the saddle positions need lengthening at all? Did the truss have to be used to counter movement in the neck? The guitar looked pretty much in "as new" condition and ye...
by Trevor Gore
Wed Jul 18, 2018 12:24 am
Forum: The Gallery
Topic: 12 fret BRW small body
Replies: 22
Views: 6455

Re: 12 fret BRW small body

Five years later (where did that go!) and in for a service. Gets frequently gigged, but well looked after. Fixed the pre-amp (the main reason for the visit), tap tested, tweaked the set-up, sorted some dings in the finish, a cut and buff and good for many more years. sDSCF0649.jpg sDSCF0653.jpg And ...