Aluminum acoustic
 

Hi all, I'm new to this forum. I'm a (decidedly) amateur luthier, and have been experimenting with aluminum body acoustic guitars. Anyone else out there tried working with an aluminum soundboard? I know Martin had their version, but I was wondering if there's anyone with some hands-on experience wanting to swap horror stories.
-Jeff
http://lobocnc.com/photos/p22.jpg

I love the rivets as rosette. Very clever.

http://www.magazineluiza.com.br/imag.../204066900.jpg

No hands on experience, but I think yours looks decidedly better than Martins' version.
I understand that there was an issue with Martin bridges coming unstuck from the aluminum top. What type of glue did you use for the bridge, is it fastened with anything other than glue?

.... I like your Logo...Lobo :D

Gluing was one of the biggest headaches to work out. I started off with regular epoxy, but it proved too brittle. I believe Martin used a methacrylate glue (kind of like Plastic Welder) which is really nasty to work with. It tried the methacrylate with some success, but then I got a bad batch which spooked me. I'm currently using a 3M toughened epoxy which has more give than regular epoxy, and it has been working well. That said, I also jam a couple of 4-40 screws through the bridge plate into the underside of the bridge for good measure. So far no failures.

I'm actually gluing up the entire body much like a wooden guitar, with wooden kerfing and spruce bracing. The toughened epoxy has really good peel strength, so that's all been working well. Surface prep is key, though.

Just curious -- why not use a milled aluminum bridge? Why not weld the joints?

Oh, and does it feel really cold when you play it in the morning? :)

There was one builder around the 1900's (probably not long after aluminum started to be mined) who used it for acoustics.

Ah, here it is. Merrill.

http://www.billcampbanjos.com/Merril...ack2_small.jpg

The bridge is ebony. I was afraid that an aluminum bridge would be too heavy - It'd be about 3x the mass of ebony.

As for welding, that's way beyond my skill level. The top is only 0.020" thick and the sides and back are 0.040". I also liked the idea of putting a little wood inside in the hopes that it would cut down on any harshness. It doesn't sound harsh at all, so maybe I succeeded...

Any yes, it is chilly to the touch at first (I'm in Bellingham), but there's not much thermal mass, so it warms up quickly.

Very cool photo of the vintage guitar.

That's fascinating. How do you join the front and sides? Is it wood kerfing, aluminium kerfing or something else?

That's very cool. I'd love to hear a recording.

Just regular old basswood kerfing.
-Jeff

Audio clip of aluminum guitar
 

My playing & recording skills are a bit limited, but here's an audio clip...

http://lobocnc.com/photos/p2tim.mp3

Sounds great! Is that a 000 body size?

Make a smaller one and market it as an alternative to the carbon fiber travel guitars.

I've already thought of a brand and logo for you....

http://ih3.redbubble.net/image.12331...er,375x360.png

Its got a 17 3/8 body length, 13 1/4 lower bout and 10 1/8 upper bout, and a 25" scale. Is that close to a 000?

No, that's a small body. Similar to a Martin 0.

It's already a travel guitar. :)

Your bridge must be smaller than normal. Typical width is 6". Probably why I assumed it was a larger guitar.

Riveting, truly! Sounds great.

I would never guess from this recording. I expected a Dobro-like tone. Sounds great. And your chops beat mine.