Search found 1215 matches

by Peter Wilcox
Fri May 18, 2012 8:39 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

Cut the sound hole, added a plywood brace around it, glued on the top braces and the bridge plate. The top has a radius of 30', the back 15'.
by Peter Wilcox
Fri May 18, 2012 8:35 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

Glued on the back braces.
by Peter Wilcox
Mon May 07, 2012 10:04 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

If the tailblock and heelblock make a right angle with the top, then the back has to be slightly longer than the top, which is 30". By using either 5/{sin[arctan (5/30)]} or the Pythagorean theorum, it comes out to 30.414". I suppose the extra length should be stretched out over the whole back, but ...
by Peter Wilcox
Mon May 07, 2012 9:24 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

A mock up to see the size of it - it's more ginormous than I thought (that's a 12" square.) It's 58" long. I was hoping to be able to play it slung on my shoulders, but that may not be possible.
by Peter Wilcox
Mon May 07, 2012 9:16 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

I cut out the top and back, and rough cut the braces for them. They're just laid out for fit. The back grafts will be continuous between the braces as usual.
by Peter Wilcox
Fri May 04, 2012 1:44 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

Since this is a completely experimental instrument, I've come up with a bracing plan to hopefully let the top move to increase low frequency volume. The long vertical braces will have a long notch cut into them, spanning the lower half of the top, and glued for an inch or two at the end. Crossing un...
by Peter Wilcox
Wed May 02, 2012 10:21 am
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

Thanks, Bob. I guess I've got to think this through some more.
by Peter Wilcox
Wed May 02, 2012 1:49 am
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

How do you know how tall to make the saddle? Trial and error after the instrument is finished? How do you test it - by listening or by spectrogram? Also, it looks like the A type bracing (as opposed to X bracing) that I drew on my plan above may dampen the top movement too much, though may be physic...
by Peter Wilcox
Tue May 01, 2012 8:56 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

Thanks, Bob, that's a nice looking top. How do you brace it to accentuate any particular frequency?
by Peter Wilcox
Tue May 01, 2012 4:34 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

I've decided to change the shape to try to get a little more air mass inside. I need to figure out the top bracing. I found this on Liutaio Mottola's site (its simplicity is very engaging): http://www.liutaiomottola.com/instruments/TinozzaAsm_files/TopBraces.jpg or I could go with a more conventiona...
by Peter Wilcox
Sun Apr 29, 2012 4:19 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

Steven Wilson wrote:Wow. That's the most elaborate clamping system I've seen for a top. Looks good.
Steven
:) Yes, I know it was huge overkill, but since it is a four piece top, and it's 31" X 21", and only 1/8" thick, I wanted to make sure it stayed flat against the bench, and that it wouldn't buckle.
by Peter Wilcox
Sat Apr 28, 2012 7:45 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

The rough neck.
by Peter Wilcox
Sat Apr 28, 2012 7:43 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

Next, the stacked heel being glued.

While jointing a board to use as a caul during one of these glue-ups, I failed to note a staple in the board. So as an added benefit to this challenge, I was able to learn how to sharpen and set up jointer blades. :lol:
by Peter Wilcox
Sat Apr 28, 2012 7:42 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

The neck is from alder. Here the scarf joint is being glued.
by Peter Wilcox
Sat Apr 28, 2012 7:35 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

The sides from the same myrtle. It's 10" wide at the near end and 9" at the distal end, so it's plenty wide enough - hopefully the straighter grained portion is long enough.
by Peter Wilcox
Sat Apr 28, 2012 7:32 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

The back wood - myrtle. Unfortunately it's only 18" wide, so I'll have to add some wings.
by Peter Wilcox
Sat Apr 28, 2012 7:25 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

Glued. It's 21 1/2 inches wide, so plenty big.
by Peter Wilcox
Sat Apr 28, 2012 7:22 pm
Forum: The Local Materials Challenge (Closed)
Topic: Acoustic bass, elliptical shape
Replies: 32
Views: 54432

Re: Acoustic bass, elliptical shape

Gluing the top.