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I have this really cool piece of 3/8 inch spalted alder that I plan to mate to a 2 inch alder body in an Explorer body shape. I am going to route channels into the body in an effort to lighten it up. I like the idea of doing this the way Warmoth shows here: http://www.warmoth.com/images/Guitar/Bodies/ChamberedTele/ChamberedTeleBuilderImage.jpg.

I want to minimize the amount of planing that I do the spalted top so I plan to plane off the back of the body of much as possible. In the end, I would like the body to be 1.75 inches thick. So here are my questions:

- How thick should the body be planed to in order accommodate sanding?
- How deep can I safely cut channels into the body without negatively impacting integrity?
- What do you think a good channel width would be?
- What do you think would be a good distance between channels?

Thanks in advance for your thoughts.

Thanks Filippo,

You bring up an interesting point - I will be cutting the body later this week so I will have a better idea about what, if any, weight reduction is desirable at that point. I planned to take the weight from the area where your arm would rest while playing.

In general, how does one counter/prevent neck diving during the build?

There was an interesting thread on chambering over on the MyLesPaul forum not too long ago. Unfortunately that forum is down right now so I can't pull up the thread...but a lot of the guys over there do chamber the body because guitars with a hardwood drop top (especially those thick carved tops on Les Pauls and such) end up weighing quite a bit.

If you're going to have a guitar that isn't perfectly balanced though, Like Filippo pointed out, it is better to have the body weigh a bit too much than weight relieve and have the neck weigh too much (otherwise you will get the neck diving). If your neck is mahogany or something it won't be an issue but I probably wouldn't do weight relief if the neck is curly maple or something else heavy like that. What I've seen a lot of people do is just weigh the body and the cap on a scale after they are cut out (before gluing the drop top on) to decide whether weight relief is needed or not.

There can be a decent amount of variation in the density of Alder, but you may already have a reasonably light body in the first place. As far as structural integrity is concerned, you will be best off leaving everything between the anchor points of the strings to the neck alone. It would be very safe to extend lines perhaps an inch from either side of the neck all the way to the end of the body, and leave that area untouched. There are plenty of ways to maintain proper balance, but the neck will likely be the biggest challenge since they tend to be made from denser woods than the body and extend so far from the center of gravity. Again, make sure it needs chambers before committing to the idea. If you decide to move forward, weigh the body and top as well as the neck. With careful planning the weight can be reduced without a nose dive.

The guitar pivots on the strap, which is usually around the middle of the body. You can remove quite a bit of the body without running into an issue, especially if you intelligently locate the upper horn and strap buttons, but also because whatever you take away towards the neck is helping the situation and tends to balance out whatever you remove from the lower bout. One of my models has a VERY light chambered body and spruce top, and it has no balance issues at all. I think balance is predominantly about where the strap buttons are located.

You should consider that an Explorer width body will cup a bit with or without chambers. I like to leave about .250" on the back so it can take a little sanding without any major problems.
You can calculate the reduction by determining the volume to be removed vs solid then determine the weight of the wood blank per cubic inch and subtract the waste. This will get you into the range, but boards always have a heavy side which I prefer to layout on the bottom/treble side.
Much easier if you have a CAD/CAM program.
Some programs will even help you find the center of gravity.
Good luck and have fun.

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