Search found 1380 matches

by Trevor Gore
Wed Dec 12, 2018 8:00 pm
Forum: Instrument Builders Forum
Topic: Modal Tuning Course in Melbourne, Jan 2019
Replies: 3
Views: 649

Re: Modal Tuning Course in Melbourne, Jan 2019: fully subscribed

The Melbourne course is now fully subscribed. Thank you to all for the interest shown.

Have a great Christmas and New Year,

Trevor.
by Trevor Gore
Mon Dec 10, 2018 10:57 pm
Forum: Instrument Builders Forum
Topic: Modal Tuning Course in Melbourne, Jan 2019
Replies: 3
Views: 649

Re: Modal Tuning Course in Melbourne, Jan 2019

As I write, there have been nearly 500 views of the message above, so plenty of interest and as of now, there is just one place left on the January course. So if you were hesitating, now is the time to jump! There is no perfect time for everyone and I know many people have family commitments in Janu...
by Trevor Gore
Sun Dec 09, 2018 11:44 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Bolt on bolt off neck - order of operations
Replies: 26
Views: 2339

Re: Bolt on bolt off neck - order of operations

Hi Trevor Thanks for the reply. Yes, I misinterpreted the paragraph about yaw and pitch adjustment. I fixed the yaw only. I guess the plan indicates that the neck is completely square and it shows the position of the mortise relative tho the square tenon The plan is a single generic drawing coverin...
by Trevor Gore
Sun Dec 09, 2018 4:18 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Bolt on bolt off neck - order of operations
Replies: 26
Views: 2339

Re: Bolt on bolt off neck - order of operations

Before any holes are drilled, the neck pitch angle has to be correct (and also the yaw and roll). From what I can make out from the pics (the wide angle distorts things a lot) you didn't have the neck fully fitted before you started drilling holes (both the mortise and the bolt holes). It seems tha...
by Trevor Gore
Mon Dec 03, 2018 7:35 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Predicted Panel Thickness
Replies: 7
Views: 2202

Re: Predicted Panel Thickness

RonRapp wrote:
Fri Nov 30, 2018 10:45 am
BTW, I am very happy with the final sound!
Ah, there's the answer to my question in another thread!

Excellent!
by Trevor Gore
Mon Dec 03, 2018 7:32 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Starting out on J45
Replies: 29
Views: 2924

Re: Starting out on J45

That's good to hear. I don't think I've ever come across a piece of stationary manufacturing equipment that would function better for being lighter!
by Trevor Gore
Mon Dec 03, 2018 7:29 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Prototype Gore Guitar Freq Request
Replies: 21
Views: 2348

Re: Prototype Gore Guitar Freq Request

Looks great, Ron!

Do you like how it sounds?

BTW, anything you do to the fretboard will increase the T(1,1) frequency. Whilst not a regular solution, it is OK to leave the fretboard end as it is. It would be far from the first with that treatment.
by Trevor Gore
Mon Dec 03, 2018 4:11 pm
Forum: Instrument Builders Forum
Topic: Modal Tuning Course in Melbourne, Jan 2019
Replies: 3
Views: 649

Modal Tuning Course in Melbourne, Jan 2019

Attention those who live south of the border: I will be running one of my 3 day Modal Tuning courses in Melbourne early next year. I’ve lost count of how many times I’ve run this course now, but probably close to 20 times, including 6 times in the USA. It has proved to be very popular. Here are a fe...
by Trevor Gore
Fri Nov 30, 2018 6:24 pm
Forum: Instrument Builders Forum
Topic: Neck angle
Replies: 11
Views: 526

Re: Neck angel

My version: Steel string acoustics have a back leaning angle so that the normal string height above the soundboard at the saddle (~13mm) and the normal action at fret 12 (E2.8mm, e 1.8mm) can be achieved. The variable that should be used to achieve these figures is the neck angle and typically resul...
by Trevor Gore
Tue Nov 27, 2018 8:16 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Starting out on J45
Replies: 29
Views: 2924

Re: Starting out on J45

Steve.Toscano wrote:
Tue Nov 27, 2018 11:57 am
All in a 2m x 3m space.
2m x 3m!!??

You was lucky. When I were a lad...
by Trevor Gore
Sat Nov 24, 2018 10:49 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Main Air is at 110 Hz, aka the A note
Replies: 6
Views: 352

Re: Main Air is at 110 Hz, aka the A note

Heading in the right direction!

Try the side mass and see how it sounds. If you need to stiffen up the back, there are ways of doing that. Let us know if you want to do that and I'll explain a method how.
by Trevor Gore
Fri Nov 23, 2018 12:15 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Starting out on J45
Replies: 29
Views: 2924

Re: Starting out on J45

I bought a drill press attachment style mortiser from Carbatec many years ago. It and the 3/8" chisel it came with haven't ever given me any trouble. I haven't even had to sharpen the chisel, though its getting ready for it now! I use it on a 16mm chuck, 16 speed drill press. Reasonably heavy duty, ...
by Trevor Gore
Thu Nov 22, 2018 10:37 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Falcate #2 Tapping Results
Replies: 8
Views: 371

Re: Falcate #2 Tapping Results

I'd call that a win! Well done! The T(1,1)3 is ~ 3.5 semitones above the T(1,1)2, so far enough away. It would have dropped from 211Hz to 205Hz mainly because of the bridge mass dropping the T(1,1)2 and causing less repulsion upwards of the T(1,1)3. It's hard to say why the T(1,1)3 is lower than you...
by Trevor Gore
Thu Nov 22, 2018 10:22 am
Forum: Instrument Builders Forum
Topic: Interesting intonation problems with two small high-performance guitars I just completed
Replies: 18
Views: 710

Re: Interesting intonation problems with two small high-performance guitars I just completed

I've just had a quick read of this so may not have picked up on all the nuances. However, it is possible that your tuner (measuring string pitch) is triggering on the second harmonic of the note rather than the fundamental. That would be quite normal on a small guitar typically plucked at L/4 from t...
by Trevor Gore
Mon Nov 19, 2018 9:32 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Calculation of brace Young's Modulus (eq. 4.4-4)
Replies: 7
Views: 336

Re: Calculation of brace Young's Modulus (eq. 4.4-4)

You have too many zero in your first row of data, column E.

Flexural rigidity is a pretty straightforward calc. You need to develop some confidence in your results, best done by "triangulation". i.e. calculate three different ways and if you get the same answer three times it might be right! :D
by Trevor Gore
Mon Nov 19, 2018 9:21 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Predicting Panel Mass SS - Lookover
Replies: 4
Views: 243

Re: Predicting Panel Mass SS - Lookover

The answers can be slightly different due to Excel, but it's most likely that slight differences are due to rounding errors. If you hand transfer data from an elastic constants spreadsheet to a panel mass spreadsheet it is unlikely that you will be transferring all 15 significant figures that Excel ...
by Trevor Gore
Sun Nov 18, 2018 3:01 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Measuring Elastic Constraints - Lookover
Replies: 9
Views: 421

Re: Measuring Elastic Constraints - Lookover

That looks about right, John. You seem to have replicated the Table 4.5-3 results.

Feeling good? :D

Well done!
by Trevor Gore
Wed Nov 14, 2018 9:49 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Calculation of brace Young's Modulus (eq. 4.4-4)
Replies: 7
Views: 336

Re: Calculation of brace Young's Modulus (eq. 4.4-4)

Density is mass/unit volume, so you need what the scales say, namely 0.172 Kg. If I change 1.687 to 0.172 in your formula I get 10.5 GPa, which is about right. Straight off the spreadsheet: =(((414.6 * 0.5085^2) / (1.0279 * 0.019)) ^2) * (0.172 / (0.5085 * 0.051 * 0.019)) I can't see where you're go...
by Trevor Gore
Tue Nov 13, 2018 10:23 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Starting out on J45
Replies: 29
Views: 2924

Re: Starting out on J45

Definitely need 3/8" or 10mm, preferably 10mm for the mortise chisel. Often, 3/8" is sold as 10mm, so be sure you know what you're getting. 1/2" is too big and 1/4" is too small! The bar size is typically 3/8" for brass (which needs filing to fit in the 3/8" hole, hence a preference for 10mm) or 10m...
by Trevor Gore
Tue Nov 13, 2018 10:06 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Calculation of brace Young's Modulus (eq. 4.4-4)
Replies: 7
Views: 336

Re: Calculation of brace Young's Modulus (eq. 4.4-4)

So, I’m a bit confused how to get that into GigaPascals (N/m^2). Pascals are a measure of pressure, units of newtons per square meter. A newton is defined here . Young's modulus, E, is stress/strain. Stress has units of pressure as above, strain is meters/meter, so the units cancel and strain is di...
by Trevor Gore
Tue Nov 13, 2018 9:05 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Measuring Elastic Constraints - Lookover
Replies: 9
Views: 421

Re: Measuring Elastic Constraints - Lookover

John, Carefully check Table 4.5-3 in the black book, especially the density numbers. You're showing 0.395 Kg/m^3. Should be 1000 times that. Also check out these threads: http://www.anzlf.com/viewtopic.php?f=33&t=4019 http://www.anzlf.com/viewtopic.php?f=33&t=3626 The 2nd edition of the books has ev...
by Trevor Gore
Mon Nov 12, 2018 10:39 am
Forum: Instrument Builders Forum
Topic: Removing old shellac?
Replies: 8
Views: 523

Re: Removing old shellac?

How old is old? Old, fully hardened hard shellac is pretty well impervious to anything, including methyl chloride based strippers. Sanding works best on that stuff. Recently applied shellac will mostly wash off with IMS, even if you used hard shellac. I've had cases where I've tried to FP WRC and on...
by Trevor Gore
Sun Nov 11, 2018 10:58 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Measuring Elastic Constraints - Lookover
Replies: 9
Views: 421

Re: Measuring Elastic Constraints - Lookover

John, Your frequency measurements look about right. Check out Table 6.1 in the white book. Mahogany will fall between spruce and rosewood. Your elastic constants are incorrect, though. Your numbers for E long (for example) should be ~ 10 GPa, which is 1.0E+10, not 1.xxE+16 as you have. Check your ze...