Let's hollow out my jazz bass, shall we?

Alright, so I've got a jazz bass that I built a few years ago. It's a great bass, with good tone, and looks really sharp, if you ask me, but frankly, it's just too heavy for me. I have a back problem, even at my young age of 23, so as nice as the bass is, it simply never leaves the case. I replaced the tuners with Hipshot Ultralights, made a few other minor modifications (contoured the body a little, replaced the neck plate with neck ferrules, replaced the bridge, converted to string-through...), and got a nice, soft, wide Taylor strap, but it's still too heavy.

So here's what I'm thinking... I know the idea of planing 1/4" off the top and hollowing out the body has been beaten to death here, so I think that's what I'll do. I'm going to use spruce for the top, since it's a tried and true top wood that's also very lightweight. Oh, and don't worry. The finish is acrylic lacquer -- very hard. I'm not going to worry about bracing, since this is just going to be semi-hollow. I don't think it will need bracing.

Question, though. Since it's going to be refinished a solid color, would there be a problem if, say, I had to rotate the top 30 degrees in order to cover the entire body? I know that if this were an acoustic with a transparent finish, that would be totally unacceptable, but I figure no one is going to see the glue line or the grain or anything. The body is 13.5" wide, and so is the top, so I doubt I'll have to, but just in case.



EDIT: Okay, my mistake. The body is 13" wide and the top wood is 13.5" wide, so there's shouldn't be a problem.

 

I took the plunge today and planed 1/4" off the top, and then began hollowing out the body using forstner bits. So far, it's MUCH lighter -- possibly 2 lbs. -- but I've still got a little more hollowing to do (that little bit highlighted on the left side, and a little more on the right) to smooth out those chambers, glue on the top, and put the hardware back on. I could take it a step further and hollow out between the pickups, and between the neck pocket and neck pickup, but I wanted to keep the body solid there. I read that doing so helps transfer the vibrations, or something like that. I think that, rather than using a router to finish the job, I might use a rotary rasp. It seems like it would be easier, simpler, and quicker.

By the way, the hole in the upper horn was done simply because I could. It does little to reduce weight, but I figured why not?

Oh, the carnage!


Marking where I'm going to rout the chambers.


I start by using a drill press and forstner bits.

 

Actually, no, it doesn't.

Because of the tummy contour on the back of the body.

1/4" Carpathian spruce!

 

The finish on the back is still mostly intact, but needs to be re-polished after it's multiple trips through the planer, so all I'm going to do is spray the top the same color and restore the finish on the back.

 

Used the router to clean up the chambers and bring them to their final depth of 1". It's a very light body now. I was hoping the top would arrive today, but it didn't come in with today's mail. Perhaps there's a pink slip in my mail box saying it's waiting for me at the post office. I'll check that now. Maybe I'll be able to get the top on today!

 

Yeah, I thought about going with a nice piece of 1/4" poplar from Lowe's, but they didn't have a piece wide enough. I then considered a maple top, since that's pretty much the standard, as far as tops go, but they're too expensive. Spruce, however, is pretty cheap (cost: $30 shipped), and it's not something you typically see on a solid-body instrument. I always like to do things a bit out of the ordinary.

And I suppose I could add piezos, but I'm not at all concerned about changing the tone or getting fancy with the electronics. I just want to finally play my bass without killing my back and shoulders.

Oh, by the way, the top arrived this morning. I was expecting it to be jointed already, but nope. I had to hit it with the router. I glued one side on earlier today and am now gluing on the other side. Here's a photo, though it doesn't really show much -- just a top being glued and clamped. I took it just now.

 

You know, I'm not really sure how much it weighed. I don't have a scale, but if I had to estimate, it was maybe 12 pounds?