Official Luthiers Forum!

I have been following this forum for awhile. You are a very talented group of Luthiers. Thanks for the education and inspiration. I am getting close to starting my first build. I have been working with wood most of my life and have a decent workshop setup in the garage.

Was planning on starting with a les paul style guitar with a chambered body. I would appreciate any comments on my initial plan for the chambering. I started with the John Catto plan and sketched in the chambering loosely based on an x-ray picture of a les paul cloud 9. The side thickness on the sketch is 0.75”. On the x-ray pic it looks to be closer to 0.5”.

Would like to chamber the full thickness of the mahogany center. Remainder of the details are a 0.25” maple back plate, a standard carved maple top, and a 3 piece maple neck. Not going to install F holes, so was thinking of leaving the back side of the front plate flat (uncarved).

Thanks in advance for any comments or suggestions

I think that would be just fine, structurally, if that's what you're asking. There's plenty of wood there for bridge, pickup and neck mounting.
Were I doing it, I'd rout out the chamber to a depth that would leave 1/4" of material for the back, instead of going all the way through and then capping the back. Only because that would be much simpler to do, IMHO. But the seperate back would be just fine. There's more than one way to get where you're going.
One possibility you might run into is feedback at high volume because the electronics are exposed to the large body cavity. I've never run into this, but have read it can be a possibility in semi-hollow construction.
If you can seperate the electronics cavity from the rest of the main cavity that might be a good idea.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

I build chambered Gibson CS336 clones which is a very similar design to the Les Paul that you are considering (uses Les Paul wiring plan), but with the smaller version body outline of the 335. Gibson call it 'tonally carved' as the top is profiled inside and out. The side walls that are left from the chambering are 10mm thick, so 0.5" would be plenty. As you can see there is no isolation of the electronics in this design, nor have I ever had any problem with feedback even at 11!

Here's a shot of the internal chambering, I leave about 6mm on the back, but this is also slightly profiled on the outside. Gibson actually take the chamber right up into the horns.



Here's some shots of a finished guitar, to give you an idea.







Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Colin, that's lovely.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

So pretty! Like candy.

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"Act your age, not your shoe size" - Prince

that is a fantastic guitar!

I think I'd leave the back with some meat as mike proposed. It will be much easier without too much weight added.

Hi,

Red flag popping up for me. I think too much wood is being removed between the neck joint and the bridge. I'm sure that when built it will play splendidly for hundreds of years, but I get too nervous at the thought of hogging out that much meat. There's not much wood between the pickups and the chamber and you're cutting the cross-channel out to feed wires to the 3-way switch which seems bad to me on its own, but this is cutting away the last little bits of mahogany on the sides of the pickup cavity.. It's kerfing in the last spot you'd want it. I feel like the cap wood will be bearing the brunt of keeping the strings tight. Jackson's RR24 (V, neck-thru) doesn't have a neck pickup option because of a rigidity/lack of wing "meat" concern. Different beast entirely, but my point is there are limits.

I'm sure it's fine, but at the very least I'd change the angle of the cross-rout for the wiring to the 3-way so it didn't overlap the pickup cavities. Or no rout and run the wires around through the cavity.

Can't wait to see what you make of it.

Great comments, thanks for the replies. Beautiful 336 guitar. Eliminating the cross route and feeding the wires to the pickups thru holes is a good suggestion.

Was initially looking at this pic of a LP BFG routing but it appeared to go to far with wood removal, particularly for a 1st attempt. They do isolate the electronics from the main cavity area with an interior partition.

Thanks again

I would certainly not rout for the switch wiring, but just run the wires round the chamber to the switch with screened cable, if you do leave a partition for the electronics, which I feel is not necessary, just drill a hole for the wires to pass through. I guess Gibson did the rout for the switch wiring because their machines were already set up for it, my guess is they just took already routed Les Paul bodies and added the extra rout for the chambers. I'd also not bother with the section routed between the tail piece and bridge, I can't see any difference that could make, just a few grams in weight, that you wouldn't notice. As you can see from my 336, when they designed the chambered body from scratch for the 336, they kept it simple, as you are not Gibson, you can do the same with the Les Paul body shape, keep it simple.

There is plenty of meat left to take the tension, electric strings run at lower tension than acoustics with very much more wood to support them, so no worries there at all.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

The wire routing channel only needs to be about 3/8" deep if that makes a difference.

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