Search found 132 matches

by Dennis Duross
Wed Sep 09, 2015 7:11 am
Forum: Archtop Guitars and Bass Guitars
Topic: Am I using the correct formula for downward force?
Replies: 11
Views: 6365

Re: Am I using the correct formula for downward force?

Matt: Having slept on it, I think you may be right. My apologies for being so dense. In the jig, it's all just downward force, and the rims are likely deforming slightly under the weight. But when strung up, the string tension helps the top resist the downward force and the deformation of the ribs--...
by Dennis Duross
Tue Sep 08, 2015 6:23 pm
Forum: Archtop Guitars and Bass Guitars
Topic: Am I using the correct formula for downward force?
Replies: 11
Views: 6365

Re: Am I using the correct formula for downward force?

Thanks for the replies. I will chase down both suggestions and see what I see. However if the equation is correct, my measurement of the break angle would have to be 4 degrees lower in order to replicate the deflection I'm seeing. And I would think that any rim deformation unaccounted for would be t...
by Dennis Duross
Sun Sep 06, 2015 1:44 pm
Forum: Archtop Guitars and Bass Guitars
Topic: Am I using the correct formula for downward force?
Replies: 11
Views: 6365

Re: Am I using the correct formula for downward force?

Barry:

This is a floating bridge design with a tailpiece.

I should have clarified that.
by Dennis Duross
Sun Sep 06, 2015 12:46 pm
Forum: Archtop Guitars and Bass Guitars
Topic: Am I using the correct formula for downward force?
Replies: 11
Views: 6365

Am I using the correct formula for downward force?

I decided to deflection-test one of my test mules, just to be sure I understand what's happening to the soundboard when downward force is applied to it. The top is braced and glued to the rims (prior to attaching the back). I tested the deflection under 10, 20, 30, and 40 lb of weight, applied direc...
by Dennis Duross
Mon Jul 27, 2015 6:50 pm
Forum: Wood and Materials Q&A
Topic: What to do if spruce ever gets rare & pricey...
Replies: 14
Views: 10575

Re: What to do if spruce ever gets rare & pricey...

Alan:

Are you saying that softwoods with the same density (weight?) have the same strength?

And the same qualities as tone wood?
by Dennis Duross
Mon Mar 09, 2015 7:21 am
Forum: Wood and Materials Q&A
Topic: rod/bar/tube material that is good in compression
Replies: 25
Views: 30963

Re: rod/bar/tube material that is good in compression

By chance, I just saw an episode of Antiques Roadshow where they showed a Larson Brothers guitar with a steel rod running from the neckblock to tailblock. I believe they said it was 19 inches across, but not sure what that would have to do with the use of a central rod. Alan: Yes, the 5.5' radius wo...
by Dennis Duross
Sat Mar 07, 2015 8:47 pm
Forum: Wood and Materials Q&A
Topic: rod/bar/tube material that is good in compression
Replies: 25
Views: 30963

Re: rod/bar/tube material that is good in compression

I don't want to hijack the thread, but yes, my reasoning was to try and isolate the top and back from the effects of the pull of the strings, and the reason is that my top and back plates are domed to a 5.5' radius, which (as it turns out) makes the plates very stiff, to the point where I'm pretty s...
by Dennis Duross
Sat Mar 07, 2015 10:39 am
Forum: Wood and Materials Q&A
Topic: rod/bar/tube material that is good in compression
Replies: 25
Views: 30963

Re: rod/bar/tube material that is good in compression

So to the original question, there's hollow carbon fiber tubes anchored to the waist on the one end (obviously, the sensible end) of the spectrum, and a big, honking, poplar beam (@ 8 oz in weight, as I recall) running from neck block to tail block on the other end (the comically over-built end) of ...
by Dennis Duross
Fri Mar 06, 2015 4:39 pm
Forum: Wood and Materials Q&A
Topic: rod/bar/tube material that is good in compression
Replies: 25
Views: 30963

Re: rod/bar/tube material that is good in compression

Mark, that last line of mine may read like sarcasm, but it's not.
by Dennis Duross
Fri Mar 06, 2015 3:33 pm
Forum: Wood and Materials Q&A
Topic: rod/bar/tube material that is good in compression
Replies: 25
Views: 30963

Re: rod/bar/tube material that is good in compression

I'm sure you're right, Mark. But the neck bolts onto the beam, so I thought I'd just go ahead and run it the whole length at the full dimension.

How much smaller would you feel comfortable with?
by Dennis Duross
Thu Mar 05, 2015 7:50 pm
Forum: Wood and Materials Q&A
Topic: rod/bar/tube material that is good in compression
Replies: 25
Views: 30963

Re: rod/bar/tube material that is good in compression

I couldn't tell you how it sounds because I haven't finished it yet, but here's a take, below.
bar.jpg
The bar is poplar, 1.5" wide x 1.125" deep, so yes, it has some heft to it.

Going to have a floating bridge, and an off-set soundhole.
hole.jpg
by Dennis Duross
Thu Feb 12, 2015 1:13 pm
Forum: String Instrument Repair: Practical and Political Issues
Topic: Notes seem to "thunk out" in the middle of the neck
Replies: 14
Views: 8795

Re: Notes seem to "thunk out" in the middle of the neck

Thanks for all of the replies. I haven't been able to get back to this yet, but am hoping to work on it this weekend. I did check the fret seating with a magnifier, and they all look like they make solid contact with the fingerboard. Also it seems to be not quite as bad as it was originally, so Wadd...
by Dennis Duross
Wed Feb 04, 2015 12:52 pm
Forum: String Instrument Repair: Practical and Political Issues
Topic: Notes seem to "thunk out" in the middle of the neck
Replies: 14
Views: 8795

Re: Notes seem to "thunk out" in the middle of the neck

Sounds like something I would do, Bob. It occurs to me that I'd be well-served by getting a fresh bottle of CA before doing any wicking. I did use CA when I fretted, but looks like an additional application is in order. Any thoughts on whether I should slacken or remove the strings or if I can just ...
by Dennis Duross
Wed Feb 04, 2015 7:51 am
Forum: String Instrument Repair: Practical and Political Issues
Topic: Notes seem to "thunk out" in the middle of the neck
Replies: 14
Views: 8795

Re: Notes seem to "thunk out" in the middle of the neck

It'll have to wait until after work tonight, but I'll check the relief (I was going for dead flat), and will check the frets for loosies. Will I need to slacken the strings first?
by Dennis Duross
Tue Feb 03, 2015 10:46 pm
Forum: Flat-Top Acoustic Guitars and Bass Guitars
Topic: Harlequin "Fat Boy", and Weissenborn new builds
Replies: 9
Views: 4324

Re: Harlequin "Fat Boy", and Weissenborn new builds

Patrick, your instruments are always so interesting.
by Dennis Duross
Tue Feb 03, 2015 10:14 pm
Forum: String Instrument Repair: Practical and Political Issues
Topic: Notes seem to "thunk out" in the middle of the neck
Replies: 14
Views: 8795

Re: Notes seem to "thunk out" in the middle of the neck

Sorry, I really didn't give enough info, did I? It's a steel string guitar, maple neck, wenge fingerboard. I don't hear it quite as pronounced today as yesterday, and now I'm wondering if (since I'd just strung it up for the first time) it was/is just sort of settling in? Still notice it to some ext...
by Dennis Duross
Mon Feb 02, 2015 10:44 pm
Forum: String Instrument Repair: Practical and Political Issues
Topic: Notes seem to "thunk out" in the middle of the neck
Replies: 14
Views: 8795

Notes seem to "thunk out" in the middle of the neck

Clearly I don't know exactly how to describe this, but fretted notes on all strings seem to have less power and sustain in the 5th thru 10th fret range. Not a problem in 1st thru about 3rd position, and they seem to recover approaching the neck block. Which makes me think that the middle portion of ...
by Dennis Duross
Wed Jan 21, 2015 6:32 pm
Forum: String Instrument Repair: Practical and Political Issues
Topic: material for Cello (rib/side)
Replies: 8
Views: 5374

Re: material for Cello (rib/side)

I've been laminating sides as a 3-ply: [inner wood (@0.05" thick)] + [1/64" baltic birch plywood (oriented 90 degrees from the inner and outer lams)] + [outer wood (@0.05" thick)] The finished sides end up a little under 1/8" but I plan on going thinner---just wasn't sure initially whether there'd b...
by Dennis Duross
Tue Dec 09, 2014 10:24 pm
Forum: Wood and Materials Q&A
Topic: African Blackwood nut and saddle?
Replies: 8
Views: 4688

Re: African Blackwood nut and saddle?

I've used it several times for both nuts and saddles, and it's great stuff. I've also tapped it a couple of times for 10-32 threads on adjustable bridges, and it's very hard. A lot cheaper than bone, if that matters. Cuts well, but will gum up your sandpaper in no time unless you hand sand.