Search found 1492 matches

by jeffhigh
Thu May 28, 2020 8:21 am
Forum: Instrument Builders Forum
Topic: The order of things ...
Replies: 14
Views: 1993

Re: The order of things ...

I drill the locating holes through the board into the neck then use plastic rod as pins only projecting 3mm from the face of the neck.
Then I can fret the whole board and just leave the pins in place.
Or I fret after gluing the board on, depends.
by jeffhigh
Mon Feb 17, 2020 10:57 am
Forum: Instrument Builders Forum
Topic: X-brace interfaces
Replies: 1
Views: 2641

Re: X-brace interfaces

Tapering down to 2mm at a butt joint between braces is essentially unconnected as far as any bending strength. What you are trying to avoid here is something like a full height butt joint which if it were to crack apart could buzz, Some older Martins connected finger braces and bridge plate to the X...
by jeffhigh
Tue Jan 21, 2020 5:56 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: compensation spreadsheet question
Replies: 5
Views: 3379

Re: compensation spreadsheet question

I had my copies of Trevors books stored away. I have pulled them out now. I'll note that the second paragraph of 4.7.3.1 indicates that the use of published values for the modus of steel are fine for steel strings, and only recommends the jig for use on Nylon or the like Classical strings I would su...
by jeffhigh
Tue Jan 21, 2020 10:32 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: compensation spreadsheet question
Replies: 5
Views: 3379

Re: compensation spreadsheet question

Are you trying to determine E from you test results? I don't see how?
It should be a constant around 190GPa as it is just a material property
Do you have a jig with pulley and weight to supply tension? The contant tension provided will not give meaningful compensation results Pictures?
by jeffhigh
Tue Jan 14, 2020 8:43 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: compensation spreadsheet question
Replies: 5
Views: 3379

Re: compensation spreadsheet question

Without getting too far into it and having to go back and check terminology etc, I suspect that your problem is that you have used the measured overall string diameter. For string longitudinal stiffness calculations, you need to use the measured core diameter excluding the wrap. The wrap contributes...
by jeffhigh
Sat Dec 14, 2019 5:11 pm
Forum: Instrument Builders Forum
Topic: Fibre Sheet for side lamination
Replies: 3
Views: 2106

Re: Fibre Sheet for side lamination

Fibre sheet would probably be quite damping too
by jeffhigh
Thu Dec 12, 2019 6:13 pm
Forum: Instrument Builders Forum
Topic: Study comparing FRC to subjective experience
Replies: 4
Views: 2177

Re: Study comparing FRC to subjective experience

It's a bit of a Straw man exercise
Put up a proposal that does not really represent anyones position then attempt to disprove it
I'll say worthless is being generous
by jeffhigh
Tue Dec 10, 2019 5:05 pm
Forum: Instrument Builders Forum
Topic: Study comparing FRC to subjective experience
Replies: 4
Views: 2177

Re: Study comparing FRC to subjective experience

Seems deeply flawed to me. To the extent of being worthless It puts up this hypothesis that percieved quality will be correlated with -the lower body frequencies being certain values (though not specified what is desirable) -the ratio of those frequencies not being 2.00 And then throws in a vast mix...
by jeffhigh
Fri Nov 15, 2019 12:03 pm
Forum: Instrument Builders Forum
Topic: Acoustic Bridge Types ...
Replies: 9
Views: 2793

Re: Acoustic Bridge Types ...

I have not made any for a while but definitely prefer the string through bridges for two reasons. - less stress on the glue joint than a tie bridge -better break angle I had to convert one factory uke to string through when lowering the saddle to get acceptable action left the strings sliding around...
by jeffhigh
Sun Sep 15, 2019 7:42 am
Forum: Instrument Builders Forum
Topic: Selmac Grand Bouche
Replies: 7
Views: 2696

Re: Selmac Grand Bouche

There should be, but often there is not.
I repaired a 70's grand Bouche can't remember the brand which was severely distorted around the soundhole resulting in very high action.
by jeffhigh
Sun Sep 15, 2019 7:30 am
Forum: Instrument Builders Forum
Topic: Selmac Grand Bouche
Replies: 7
Views: 2696

Re: Selmac Grand Bouche

There should be, but often there is not.
I repaired a 70's grand Bouche can't remember the brand which was severely distorted around the soundhole resulting in very high action.
by jeffhigh
Fri Jul 19, 2019 10:18 am
Forum: Instrument Builders Forum
Topic: Lefty Build
Replies: 5
Views: 2733

Re: Lefty Build

You would not want to wire audio taper pots in reverse. It would be useless.
You can get the Lefty Pots from these guys
https://www.realparts.com.au/left-hand-parts.html
by jeffhigh
Fri Jul 12, 2019 8:47 pm
Forum: Jigs & Fixtures
Topic: My dust collection system
Replies: 5
Views: 6456

Re: My dust collection system

Just out of curiosity, why two disc sanders?
by jeffhigh
Sat Jun 29, 2019 12:51 pm
Forum: Instrument Builders Forum
Topic: New acquisition. Southern Silky Oak.
Replies: 8
Views: 4360

Re: New acquisition. Southern Silky Oak.

And make sure any end grain is sealed well
by jeffhigh
Fri Jun 28, 2019 7:03 am
Forum: Instrument Builders Forum
Topic: New acquisition. Southern Silky Oak.
Replies: 8
Views: 4360

Re: New acquisition. Southern Silky Oak.

I have found it to move quite a lot with humidity changes (used in making small boxes)
It would not be my choice for neck timber.
by jeffhigh
Thu Jun 13, 2019 6:44 am
Forum: Instrument Builders Forum
Topic: travelling with several guitars?
Replies: 7
Views: 2524

Re: travelling with several guitars?

On an Archtop, I'd be taping the bridge in position and padding under the tailpiece
by jeffhigh
Mon Jun 10, 2019 8:08 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Gore method/Tap tune/Siminoff...help!
Replies: 13
Views: 6688

Re: Gore method/Tap tune/Siminoff...help!

IMHO forget Siminoff He is worse than useless because his principles and methods will lead you astray The Main aspects of the "Gore Method" are -materials testing by tap and then plate thickness calculation -Modal tuning where the finished guitar is tested and adjusted It does NOT tell you how to tr...
by jeffhigh
Tue Jun 04, 2019 9:24 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Cutting The Neck Tenon With a Table Saw
Replies: 6
Views: 5337

Re: Cutting The Neck Tenon With a Table Saw

If I were doing this (and I am not, I use a different neck joint) I would be building a dedicated double sided sled with accurately positioned fences on both sides. Set it up with a 90 degree saw blade and a stop right across to the end of the tenon Use a shim at the headstock end to give the 5 degr...
by jeffhigh
Sat Apr 13, 2019 9:16 am
Forum: Instrument Builders Forum
Topic: Finishing advice - colour under oil??
Replies: 2
Views: 1472

Re: Finishing advice - colour under oil??

I have used the Feast Watson Prooftint under wipe on poly on furniture without issue.
I would suspect that asking about compatability with oil is confusing people.
by jeffhigh
Wed Apr 10, 2019 6:00 pm
Forum: Instrument Builders Forum
Topic: Acoustical effect of back woods
Replies: 25
Views: 8485

Re: Acoustical effect of back woods

I agree with a lot of Peter Coombe's concerns about the methodology of this study. In addition -what the guitarist hears of the guitar is dependant on room acoustics - The fact that the guitarist hears the instrument as he is playing it means that they can make subtle adjustments to playing style to...
by jeffhigh
Sun Feb 24, 2019 10:50 am
Forum: Instrument Builders Forum
Topic: Twisted Ringed Gidgee
Replies: 2
Views: 1514

Re: Twisted Ringed Gidgee

If the blank is overthick and oversize as they mostly are, cut it to length and width (to minimise the amount of twist you have to deal with) then flatten one side and use that as a base to thickness to final. The exact process will depend on what gear or machinery you have. Dealing with it this way...
by jeffhigh
Wed Feb 20, 2019 7:52 pm
Forum: Instrument Builders Forum
Topic: Old build, dead guitar
Replies: 7
Views: 3098

Re: Old build, dead guitar

The guitar may just be overbuilt with a top which is too heavy and stiff.
You can't really tell just from a tap spectrum unfortunately, and tapping the back is fairly irrelevant.
You would need to do the deflection testing and uncoupled testing tap testing.
by jeffhigh
Wed Feb 20, 2019 7:21 pm
Forum: Instrument Builders Forum
Topic: Testing existing top and back
Replies: 9
Views: 3391

Re: Testing existing top and back

I'd suggest you just use the existing top and back at current thicknesses, brace and assemble and then test. You can always thin the plates in situ. The results from static testing of a shaped back and top are going to be suspect and can't just be rectified my averaging the width as suggested. For o...
by jeffhigh
Wed Feb 13, 2019 8:20 am
Forum: Instrument Builders Forum
Topic: Testing existing top and back
Replies: 9
Views: 3391

Re: Testing existing top and back

If you are testing "existing top and back" disassembled from the body as your title implies, all the regular material testing methods will not work since they rely on using rectangular uniform pieces.
by jeffhigh
Wed Feb 13, 2019 8:09 am
Forum: Instrument Builders Forum
Topic: Homemade fret/fingerboard leveller
Replies: 5
Views: 2537

Re: Homemade fret/fingerboard leveller

IMHO length is vital,
A 16" beam with 320 grit is far superior to a shorter file, even if you get a good one.