Aluminum 6-string Bass

[skibum5545]

Hey all! It's been a very long time since I posted-- mostly because I went off to college and had no woodshop-- but I've been taking time off from school to learn to weld, and built this thing as a sort of final project for the year. I figured y'alls would appreciate it, so here it is!

I bought an Ibanez BTB 6-string, and replaced the body with a semi-hollow aluminum one. It's all welded by hand, and yes, it is extremely heavy (16 pounds!!)

I sketched up the body shape a couple years ago when I thought I would be using it for a guitar:

The body has a central framework with two parts: an upper part made of 1/4" struts and 5/8" deep, which defines the neck and pickup pockets, and has supports for the bridge to bolt into (which were not yet attached at the time of this photo):

This framework was welded to a 3/4" thick spine, which made up the rest of the body thickness, and provided a nice, solid base for tonal transfer between the neck and bridge:

The top and back were plasma cut from 3/16" aluminum sheet:

After attaching the back, the sides were attached by repeatedly tacking and bending an 1/8" thick strip of aluminum around the sides, and the top was welded to the sides and central framework after that. Alas, I don't have photos of this progress, but here's the body immediately after the top was attached:

The gap at the bridge section is there because the individual string bridges do not sit flush on the surface, but instead protrude by about 3/8" below the surface. The Ibanez body had individual routs for the bridges, but I decided that, since my body was hollow anyway, I'd simply not put any material in the way in the first place.

After this point, all that was left to do was grind off the welds, drill and tap bolt holes for all the hardware and electronics, and do a little carving. I created the arm bevel by grinding through the top and side with an angle grinder, then welding the gap closed with a bunch of filler rod and grinding it flat again. I got the finish on top by sanding out as much of the scratches and weld impurities as I could (there are still a number of small voids along the welds that are visible under close inspection) and swirling the top with an air grinder and Scotchbrite pad:

I decided to leave the back fairly unfinished, because I rather like the industrial look and wanted to leave some welds showing. I simply sandblasted the back and then brushed it out with steel wool:

I decided to put my school's logo on the backplate, by polishing the plate, masking out the logo with a vinyl decal, and sandblasting it:

I'd also like to take this opportunity to give major props to the welding program at Washtenaw Community College in Ann Arbor, MI-- it's respected as one of the best programs in the nation, and having had a chance to participate in it and be a part of that whole enterprise was a truly great life experience.

Here's one more picture of me holding the bass:

Some specs:

Maple/walnut 5-piece laminate neck with rosewood fretboard, 35" scale

Semi-hollow aluminum body (6061 alloy for optimal stiffness to weight ratio, with 5052 sides for bendability)

Bartolini mk-1 pickups with preamp and 3-band semi-parametric EQ

Brushed nickel hardware with black straplocks

Regarding how it sounds: first, it sustains forever. Seriously, I tried to time it at band practice a few days ago, and we all got bored and moved on to the next song before it stopped ringing. The body attenuates almost no frequencies, so the tone is clear, bright, and punchy, if not as warm as a wooden body bass. I'll try to post sound clips soon.

I put a whole lot of work into this project, and I hope you guys like it as much as I do.

[Akula]

Thats pretty awesome. I'd love to try something like that.

How much did the aluminium cost, overall?

Did you know it was going to turn out that heavy? Was there anything practical you could do about it?

[skibum5545]

All told, the aluminum cost 50 or 60 bucks. I didn't have to pay for my own filler rod (the fab shop supplied it) but that would have been another 10 or so.

I knew it would be heavy, though I didn't know exactly how heavy. I could have made the whole body thinner, and in retrospect, I should have used 1/8" material for the top and back rather than 3/16". I took some steps to reduce weight (note the odd shape of the central frame, instead of just a big rectangular block of aluminum) but reducing the 3/4" thick block to 1/2" and the top/back to 1/8" would've shaved off a few pounds.

Of course, it is a 6-string, so a big body was sort of part of the game, and the lack of a top horn meant the body needed to be heavy to avoid neck-heavy balance issues. As it stands, it balances very well, and I bought a giant padded strap to help with the weight.

[skibum5545]

Here are some sound clips: one is only the bridge pickup, which has a cool, modern, hi-fi, sound, and the other is a metal riff using both pickups (get it? Metal? hurr hurr).

http://soundcloud.com/dmd53/bothpups

http://soundcloud.com/dmd53/brpup

Finally, a live track from last night, with the bass boosted so you can hear it better:

http://soundcloud.com/dmd53/yessica

[Muzz]

Fantastic, love the look of the swirls.