Tips on "clamshell" chambered body construction?

blackbelt308

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I used to own the guitar in the photo... It was stunning! But it also weighed almost as much as my car! Having recently scored some very nice figured black walnut, I want to build a new Jazzmaster, complete with the maple sandwich, but this time appropriately chambered. I've built several thinline style Teles, but rather than a simple cap over core wood, I'm thinking this one ought to be done with a "clamshell" approach using two carefully hogged out halves (including the forearm & belly cuts).

I know some of you build bodies this way, and without CNC. Care to share some pointers?

Thanks a bunch!
Rick

Rosewood JM 3 copy.JPG
 

schmee

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I've considered doing it. But haven't. I've thought it's less work to do one half hogged out and put a cap on it than two hogged out halves...?
 

DJLockjaw

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What pickups are in that thing? I'm not a fan of the bridge in my jazzmaster, and would LOVE a humbucker that would fit the existing rout.
 

gb Custom Shop

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Here's a really good build thread that utilizes that construction method, albeit for a tele. With a JM you'll just need your chambering to account for the comfort contours.

 

telemnemonics

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I've considered doing it. But haven't. I've thought it's less work to do one half hogged out and put a cap on it than two hogged out halves...?
Right, thin cap makes more sense and you only rout the one rather than two halves.
For a JM or Strat with contours I’ve seen it capped from the back.
 

Si G X

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can't help, but following along.

... and for what it's worth, I think it's a great idea. 😄

Just looking at the pic in first post, most of the 'hogging' would be in the back half, which is 'easy' as long as you leave enough wood for the belly cut.

The front half, by the time you've routed everything under the pickguard and left wood for the arm contour, there's only really a bit in the top horn and in the bottom corner left isn't there?
 

eallen

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Oddly, I have had a PJ bass doing the exact thing on my build requests waiting for me to get to it for a year. I hope to get started in the next month. I dont know if I will have time to do a thread but if so I will.

I will be using one of the solid bass sized billets of Crotch walnut I have in stock. They want it resawn so that the grain on each side of the maple matches up. Fortunately my bandsaw has a 14" resaw capacity to manage it. If a solid blank is to be used and you dont have that resaw capacity it will require cutting the block down the centerline first and then resawing both halves. But before that...

For chambering, I use a thinline style template. I will minimize removing material from the belly cut and forearm areas and primarily remove it from the treble side.

As for how to do it. If using a solid blank as I am, place your thinline style template on the block and drill 1/8" holes in 2 opposite corners in the area that will be in the cutoff area outside the body. Then resaw the body blank. If quartering cut the black down the centerline first & clamp together before drilling the corners.

After separated, run all the surfaces over the joiner and glue the maple to one half. If quartered glue the 2 side of each together then glue the maple on the top or bottom. Once done, pin the template on the inside surface of each half and route the chamber as desired. Glue the top and bottom back together and keep on building.

Enjoy!

Eric
 

blackbelt308

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Really appreciate all of the comments so far!

I've done the traditional thinline approach before with rosewood and a layer of curly maple as you can see below, but for the JM I really want that maple layer centered in the body. Still thinking I'll give the clamshell approach the old college try...

rosewood 4.jpg


DJLockjaw: those are Curtis Novak's JM-WR pickups. The rhythm circuit controls were used as a dial-a-tap mechanism.

Thanks!
Rick
 

mistermikev

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I've done a lot of thinline... and have processed the back side of a top or two... if I was going to do this... what I would do is just make a template that can be used for either side. perhaps have a support/bar running across the area that will be cut with a forearm cut. Flip the template and use it to cut the other side. on the back side of the forearm area I'd measure out the angle I was going to use and just put 'steps' into the backside of the top leaving 1/4 of material under them at all times. I've done similar for my belly cut with a thinline design. You might want to mock up the body/controls/cavity in an editor like gimp... so you can plan to keep 'walls' around your electronics so that shielding is easier.
below shot of backside of top relieved for bending.
 

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Peegoo

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I've done a bunch. I've done it using a router, but prefer Forstner bits for the job because it creates a honeycomb that provides more support for thinner tops and backs.

My first step is to make a full-scale drawing of the body outline and lay out the locations and sizes for the drill job. With all center points market on the paper, I use that to transfer the center points to my wood slabs. It's pretty straightforward.

Here's one made from three slices like a cheese sammich:

Chestnut-and-Yellowheart-Montage.jpg


Here's a build thread on a pine body I sliced in half like a layer cake:

https://www.tdpri.com/threads/for-my-next-trick-sawing-the-lady-in-half-with-a-twist.993606/

This stuff is pretty simple to do; nothing complicated at all.
 

Pullshocks

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Bob J

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On my esquire build I’m doing, I went with the clamshell honeycomb, with no contrasting center slice. Was able to reduce the weight by about 1-1/4lb.
F1E587A7-D09D-4D01-882C-B0917EB23592.jpeg

My tip is be careful not to drill too deep, and maybe grinding the tip off the forstner bit.
B20B6B6D-EB9B-4ECB-945B-510A637912A1.jpeg
 

blackbelt308

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And we have chambering templates!

For the top half of the body:

JM chamber top template.jpg


And the bottom half:

JM chamber bottom template.jpg


And, since I also found a killer piece of Honduran mahogany and will have plenty of Ohio black walnut for a centered "sandwich" layer, I whipped up a Tele chambering template as well...

Tele chamber template.jpg
 

montyveda

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upon seeing your opening post i was going to post a picture of the template for chambering my hollocaster... but you've pretty much done what i did, so no need. Looking good 👍
 

novakane

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Kind of on a whim/see if I could make a guitar out of a piece of pine project board that was taking up space for several years, I designed and made a "clamshell" guitar in 2020. This was done all by hand, I was turning forstner bits with a brace rather than a drill press.
One thing I found quite helpful was having a template - and I used a pair of dowels (seen on the upper section in the picture which is actually the bottom half of the guitar). My template was double sided so it was showing the layout for whichever side it was laying on and the dowels could be moved to either side to hold the template. (Let me know if that makes sense or if you'd like to know more, I probably have more pictures)

Also - do NOT do what I did here - as you can see the one side is already closely shaped, I should have left a lot more space and done the final out side shaping after they were joined. Live and learn, this guitar ended up needing to be painted due to that and a few other mistakes.
Not bad for my first time ever carving wood with hand tools, all said and done.

IMG_2125.jpeg


IMG_2834.jpeg
 

novakane

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Kind of on a whim/see if I could make a guitar out of a piece of pine project board that was taking up space for several years, I designed and made a "clamshell" guitar in 2020. This was done all by hand, I was turning forstner bits with a brace rather than a drill press.
One thing I found quite helpful was having a template - and I used a pair of dowels (seen on the upper section in the picture which is actually the bottom half of the guitar). My template was double sided so it was showing the layout for whichever side it was laying on and the dowels could be moved to either side to hold the template. (Let me know if that makes sense or if you'd like to know more, I probably have more pictures)

Also - do NOT do what I did here - as you can see the one side is already closely shaped, I should have left a lot more space and done the final out side shaping after they were joined. Live and learn, this guitar ended up needing to be painted due to that and a few other mistakes.
Not bad for my first time ever carving wood with hand tools, all said and done.

Having said all of that, I now notice that you're using thick MDF templates so I guess you're going to do the work with a router. I'd still recommend using some sort of wood indexing pins. Helpful not only for aligning the templates but they get left in when assembling which really helps keep things from sliding around when you do the glue up. (Much like they do when pinning a fretboard down or when doing a scarf joint on a neck)
 




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