Thinline Jazzmaster with Both Contours!

[Deed_Poll]

Hey guys! This is a first for me so I thought I'd document the process a bit and do a build-along

The challenge is how to achieve the top and back contours with a hollow / Thinline construction. I've done one or the other before as a Thinline, basically machining the body core in 3D inside and out, and capping it off with my standard 1/4" marine birch ply top (for belly cut) or back (for arm contour).

This Thinline had a belly contour and shows the process pretty nicely:





Here's the inside of the body core (before cutting the belly contour on the outside). You can see I've extracted the shape of the belly cut and used it for the inside cavity cut, so that the cut leaves a consistent 1/4" back thickness.



Then I cut the corresponding contour in the back



Here's the top, with reference holes to glue to the core so the f-hole and control cavities are in the right place



And here's the whole thing clamped up and gluing the top to the back. After this stage, I simply line up the reference holes with the bed and cut the body from the front as usual.

[Deed_Poll]

So I adapted the above process to try and tackle a Thinline with BOTH contours. What I would have to do is basically the same thing, but the top AND the back would have to be like the body core above. Instead of a thick core and thin top, I would have to split the difference and start with two boards approximately one-half the thickness of the finished body. So I got in touch with my supplier and ordered a stack of 1" thick, 44" long and 7"-8" wide heat treated maple.



Each of these boards would be sawn in half, and doubled back to make either a top or a back. It would take two whole boards to make a body, and each body would be 4-piece (two on top, two on the bottom) with a join down the centre and a 'pancake' join mid way around the body perimeter.



Here's a print-out to check that Nico is happy with the f-hole shape and location. I also used it to pick some suitable boards for the build and locate any knots and things to make sure they would not fall on the finished body.



These are the ones I chose, they're a good match for each other in terms of grain and colouration and are just the right size. I order 1" thick stock knowing that I will have to plane them off to 21mm-22.25mm (for a finished thickness between 1-5/8" and 1-3/4"). Obviously, for each guitar all the thicknesses will be the same! The range is just a handy reference.



You can see there will be a fair bit of planing and thicknessing involved to get these straight, square and planar!



And here's the first pair after planing and thicknessing ready for glue and clamping. This will be the top. I've left this to glue overnight, and the back will be clamped up tomorrow.

I'm gluing the top first because it will be the first side to be machined - I will be cutting from the top, and will do the f-hole, pickup routes, and the control routes (cutting them just deep enough that the "hollowing out" pass from the other side will reveal the cavity).

Then I will do the hollow pass (back of the top), then the hollowing pass of the back (too of the back), and then it will be time to clamp the top to the back.

Stay tuned!

[kdanie]

Love it! I'll be watching as it progresses.

ken

[Unicorn Warrior]

+1 looks like a great concept in the making

[sirspens]

Ooohhhhhh.... so nice

I've been wanting to do a thinline with both contours for my G&L inspired offset. This gives me a lot of hope.

Also, I want one of these!

[Deed_Poll]

Cheers guys! Much appreciated

Sirspens, yes I have been watching with great interest. I love what you're doing with that build! I had a go designing a G&L style offset a while back with this, which I'm yet to make yet:



I have thought about doing one of these as a Thinline with both contours, sticking to the tele-ish theme. That could look cool with your G&L pickups and hardware choices!



Or maybe even get around to making a StarBacker! One of these days...

[Shadoweclipse13]

This is cool as hell! It'll be very interesting to see how the contours affect the weight and acoustic sound, if at all.

[NickD]

Also watching with interest, I've been wanting to do a Thinline Jazzblaster for sometime, but the woodworking is beyond me.

[kosta]

This is awesome. I had Guitar Mill make me a mahogany CFM thin line Jazzmaster body. It's great, but missing the contours. This is definitely a worthy pursuit!

Pic here if anyone's curious: https://www.instagram.com/p/BMO-4XAjKJd ... hare_sheet

[Deed_Poll]

Part 2! Great to have you all along for the ride on this one

I thought it had all gone perfectly, but alas there was a problem! I'm quite sure it's fixable though. Just very, very annoying.



Things initially look good from the front! The first cut was doing the f-hole, pickup and control cavities from the front. Not to full thickness, because the Thinline cavities would intersect them from the back... Though this picture is taken after that.





At first glance, the underside looks decent as well. This is still attached via the reference pegs to the machine bed. I use 4.5mm wooden dowells for this since that way I can use the same tool I use for the neck bolt holes. The piece is also fixed down by vacuum (I'm a belt and braces kinda guy!)



I cut the treble side cavity with an end mill (square bottom). Where it overlaps with the control cavity, it is well within my standard 0.1mm allowance. The circle you can see by the cavity is to give the pickguard screw in that location something to bite into.



These bumps on the bass side perform the same function. The Jazzmaster was never really meant to be a Thinline, so I had to improvise a couple of things!



Here's the disaster area. So my method is to lower the tool pass around the f-hole, so that the edge of the f-hole looks like it is 1/8" thick rather than the 1/4" thick the bulk of the top actually is (Fender did this as well with their thinlines).

But you can see here, I was unlucky this time and got a splinter right along the edge of the f-hole... that will be visible from the top as you will see, so I'll need to fill that in to the correct thickness and reshape it flush with the edge before I can join top to bottom. Really annoying!



Here it is from the other side, clearly visible and horrible! Sorry, Nico! It will be put right I promise!



Inside is like a Zen garden! I'll machine the visible side (inside of the back) a lot finer than this, but I perversely like the idea of leaving some invisible evidence of how the thing is made.

The back is now patiently gluing up, more on that in part 3!

Cheers

[blimpage]

This is fascinating. I can't wait to see it put together.

That StarBacker design is really interesting too, it works so well!

[gishuk]

This is all looking great but the StarBacker is PERFECT it needs to exist!

[MayTheFuzzBeWithYou]

This is all looking great but the StarBacker is PERFECT it needs to exist!

Cool mashup indeed. I've also dreamed of a mixture between a Rickenbacker 480/481 (whatever...a guitar in THAT Ric-bass-shape) and a Jazzmaster. Doesn't need to be a thinline but if so, with the Ric-Cat-Eye of course!
Duesenberg has done something a bit similar with the double cat - but it's not quite what I mean...

EDIT: also love your wood choice and I'm curious about the result! Having a Thinline Jaguar I'm a bit in the other camp though. As my next built will be a non thinline but with all the bindings so no contours...

But for all of you who are interested in another cool offset Jazzmaster. I just stumbled across this one. Located in spain. Shipping to EU only. No affiliation!

[sirspens]

But you can see here, I was unlucky this time and got a splinter right along the edge of the f-hole... that will be visible from the top as you will see, so I'll need to fill that in to the correct thickness and reshape it flush with the edge before I can join top to bottom. Really annoying!



Here it is from the other side, clearly visible and horrible! Sorry, Nico! It will be put right I promise!

Have you considered binding the interior of the f-hole?


Fender Coronado

[NICQ]

Here it is from the other side, clearly visible and horrible! Sorry, Nico! It will be put right I promise!

No problem - "Where wood is chopped, splinters must fall"
I was going for a solid Sonic Blue finish so you don't have to think about repairing it meticulously or mathcing the grain or wood too much

Build looks great so far - very excited!

Have you considered binding the interior of the f-hole?

That would look cool if the whole body had a binding... but that I think of it - the neck for that guitar will be bound indeed so..... hmmmmm