Australian/New Zealand Luthiers Forum

Those are typically called brash fractures and are typically caused by the wood failing in compression, usually on the compression side of a bend, so they sometimes get called compression cracks. Clearly, it weakens the wood considerably, leading to early failure when the the compression crack sees ...

I wonder whether metal glue, which is heat resistant, would be a suitable alternative to the Aerodux 500 you used back in the day? "Back in the day", when I was doing a lot of sailboat racing, the masts I used were made by a mob called Needlespar. They were constructed from tapered aluminium extrud...

GregHolmberg wrote: ↑

Thu Aug 07, 2025 2:56 am

....but I'm having fun. And that's what matters, right?

Definitely! But don't forget the acoustics project!

Maybe Trevor can explain more about how he fits a 4DOF model to a guitar. Write an objective equation and use a multivariable optimiser. When I did this for the model in the book (including the "simple sources") , I set the optimiser running and came back 2 days later when it had finished. And that...

Thanks, Alan. Properly heat proof wood glues are hard to find...

That's a striking guitar, Alan, and welcome to the falcate club! A quick question if I may: How did you do the sides? If you glued before bending, what glue did you use? My glue of choice for that application would be Aerodux 500 (which I used for boat building in the UK in the 80's and 90's). But i...

But has it survived the ultimate test of resilience.....a full on bar room fight? This one didn't survive a bar room fight. It got stood on (accidentally). The guy was heart broken. P1040666s.jpg Whilst braces were broken, they cracked along their length or split away from the top, rather than snap...

On the J 45 drawing #1 only the top end of the X braces are housed into the linings. The bottom ends of the X braces are feathered and not set into the linings. Is this normal on all X braced guitars? Most guitars have the bottom ends of the X braces set into the linings, which is fine if you want ...

...I am considering using New Guinea rosewood for the soundboard. This would be counter to traditional wisdom due to its density, but because of its amazing tap and the different setup of an archtop I feel it could be worth the experiment. I'll be attending Trevor Gore's masterclass which could pro...

kiwigeo wrote: ↑

Thu Apr 17, 2025 7:39 am

Trevor...when is the glue proof edition of The Books coming out??

And what exactly were you doing to stick the pages together??

Maybe it's time to invest in Ed 3; but a warning, some of the pics are even more provocative!

Is there an appropriate way to use dynamic testing for such material? The good news is "Yes there is!" I once came across a formula on the web which gave the resonant frequency of trapezoidal section panels. The bad news is I have never been able to find that formula since! However, a regular trape...

...is elastic modulus the same as Flexural modulus in this use or is just closely related? Flexural modulus and elastic modulus tend to be the same in isotropic materials at small deflections. For larger deflections, as typical of bending tests, and non-isotropic materials (like wood) they tend to ...

To reduce a resonant frequency you can add mass or reduce stiffness To raise a resonant frequency you can add stiffness or reduce mass The mass of a brace is proportional to its height The stiffness of a beam (brace) is proportional to its height cubed (i.e double the height it is 8 times stiffer in...

It is possible to get comparative results, but you have to be very careful about how you do it. The problem with the static test is that the longer you leave the load on, the greater the deflection you get, due to the visco-elastic behaviour of wood, leaving you with a decision as to when to take th...

In fact here it is, the timber arrives tomorrow.... That looks remarkably like my bench! Having used mine for ~20 years, here's a few things to consider: Make both the bench vises double screw (the wide front vise will wrack too much on a single screw). One day, I'll make that change! Make at least...

Trevor will no doubt respond as he always does with his sagely advice and make it all look embarrassingly simple :? Ha! I just looked up one of my old engineering text books.... it took 119 pages of "background" before it could sensibly discuss shear stress in beams. That's why the detail is not in...

If you're following the book process (back on sides, then close the box with the top) you have the opportunity to tune the back B(1,1) resonance before gluing the top on. Make the main back brace a few millimeters taller than normal and don't scallop it. Glue the back on the sides and flush trim it....

You can make a jig up using drill bushings (and it looks like Nigel did exactly that). P1010087s.jpg The screw-in drill guide bushings came from Lee Valley Tools: https://www.leevalley.com/en-gb/search#q=Drill%20bushings&t=product-search-tab&sort=relevancy&layout=card&numberOfResults=25 One is made ...

I played around with the above kit to try and find a user friendly configuration for teaching purposes. I wasn’t altogether successful, but here’s what I did and some of you might figure out how to do things better (and let us all know about it!) First, I wasn’t totally convinced about the security ...

Because the Facmogu amp is so small, it will fit inside the speaker tube. P1010027cs.jpg It can be controlled via Bluetooth from VA on your PC, so access to the amp itself is not required. This installment shows you how to mount the amp in the speaker tube. The only external “hard” connection requir...

A minor clarification: Where I said... You should hear a 1kHz sine wave through your left computer speaker. If not, check that you have your speakers on in Windows and then check the “Dev” (for Device) tab on the initial VA screen. On the “Dev” tab select an appropriate output device. Hopefully that...

According to Google translate, Facmogu means "Send out mushrooms" :wink: This next part is about using the Sig Gen functions in Visual Analyser. There are many versions of Visual Analyser and most of the time I use one of the earliest versions (v 9.0.6) because it does what I want with least hassle....

OK, there weren't may suggestions there! But we'll move right along, anyway! Those of you who wanted to get into Chladni patterns but were daunted by the build complexity of the kit shown above, rejoice! There is a much simpler solution, versions of which many of you will have adopted already, namel...

I am re-visiting the DIY sig gen topic due to new hardware becoming available that looks very promising (having already tested it). What I am seeking now is a sig gen app (preferable for free, but not necessarily so) that will run on a PC where the frequency is continuously adjustable using a mouse ...

Yikes!!! I gave up using collet reducers many years ago, due to eccentricity issues. I never had an incident, but it always looked like one waiting to happen. I now only use routers where proper interchangeable collet sizes are available (primarily DeWalt (1/4", 6.00mm, 1/8") , Makita (1/4", 1/8"), ...