Chad McCormack's "Equator" Semi-Hollow

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Chad McCormack
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Chad McCormack »

Hi Art. Come to think of it, I did actually use a dish carving bit (same as the final body chambering) to get some of the heel block down. THEN it was on to the rasp/file/scrape/sand. Time consuming, yes, but worth it in my opinion for the end result.

Adam Savage
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Adam Savage »

Chad,
As per moderator request (sorry Greg!), I'll post my next couple of questions here.
I suspect that following your exact methods would be tricky as I do not have access to machinery capable of milling the bookmatched top/back. However, I see that as only a cosmetic issue, and not one that would adversely affect a build.
As mentioned previously, I would like to attempt a carved top/back, and wonder if a stepped-contoured internal rout could then be followed (in a similalr fashion to a traditional archtop) by an external rout to obtain the carved shape?
As you have built several of these, do you find pickup choice is a little different with the hollowbody approach?

Thanks,
Adam

Chad McCormack
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Chad McCormack »

Hi Adam. These are flat top and back. I've not attempted a carved (arched) top and back with these, although I don't see any reason why it couldn't be done. As for pickups, I've only used StewMac's golden age humbuckers, both standard and overwound. I like the standard, personally. I'm sorry, but I don't really have any advice on, say, wax-potted 'buckers vs. not for a solid vs. semi-hollow. Perhaps someone with more experience can chime in on that one.

Adam Savage
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Adam Savage »

Hi Chad,
Thanks for the reply - I wasnt sure if you would need to go for pickups that are less likely to feedback (if that's even possible) when used in the hollowbody.
A last question = do you use the same internal routing on each instrument? Or does varying the routed shape alter the sound appreciably?

Your input is most appreciated.

Adam

Chad McCormack
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Chad McCormack »

Honestly, being an electric guitar the chamber routing probably has more to do with weight reduction than it does with sound qualities, for the plugged in instrument anyway. It's a solid block through the bridge region, and while there might be a *bit* more "woodiness" or "airiness" to the tone, I don't know that subtle changes to the chambered regions would make much difference at all. If it was a true archtop hollowbody, then of course we'd be having a different conversation altogether, and people who actually know what they're talking about would be chiming in about things like tap tones and bracing, etc. :) What I can tell you is that a solid, humbucker Tele build of mine strummed while hanging on the wall has a typical unplugged electric sound, while this equator strummed while hanging on the wall has a much fuller, more acoustic sound. Plugged in, those differences really narrow, because the pickups are experiencing pretty much the same thing in both instruments.

James Tonguet
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by James Tonguet »

Very nice work

Louie Atienza
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Louie Atienza »

Chad that came out awesome... I remember how much "fun" it was to rough out a chamber on a drill press... Love the work at the heel, very sleek...

Chad McCormack
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Chad McCormack »

Thanks Louie. The dish carving bit, in my opinion, is the way to go to clean up after all the forstner work on the drill press when chambering. Mine is a 3/4" D Freud bit with a 1/4" cove that gives me a really clean fillet all the way around the boundaries of the chamber.
Chambering process 3.jpg
Chambering process 4.jpg

Adam Savage
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Adam Savage »

Chad - a couple of further questions if I may. How thick do you make the sides and the top/back plates? And do you think using a standard pattern-following router cutter (and the corresponding right-angled corner it will produce between the base and the wall) would give too much of a reduction in strength if the wood thickness is around 1/4"?
Thank you,
Adam

Chad McCormack
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Chad McCormack »

Hi Adam. Side thickness is around 3/8" to 1/2" all the way around except for the obvious spots pictured above, and top and back are a bit less than 1/8", say 3/32". The bit that I use for the chambers is a dish carving bit, which is a top-bearing 3/4" wide bit with a 1/4" radius profile. I use that bit precisely because I don't want a 90 degree angle on the inside with a 1/2" roundover on the outside. If that guitar drops on a corner, I feel like I'm going to have a better chance escaping tragedy with the fillet vs. the square bottom... that, and I just think it's a slicker treatment of the chamber, even if nobody's ever going to look in there :)

James Tonguet
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by James Tonguet »

very nice work !

Adam Savage
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Adam Savage »

Hi Chad,
I truly appreciate the answers you have given to my multiple questions - another example of the generosity of folk on this forum.
I have secured a quantity of reclaimed afromosia (college workbenches - at least 30 years old), and have begun the process of milling the timber into a front and rear blank. So far, the grain is superb for the front (a bookmatched beeswing type pattern), and utilitarian 3-piece for the back.
All I need to do (apart from generate some free time!) now is to make the routing templates for the chambers and design an f-hole for the front.
Once again, thanks.

Adam

Dave Locher
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Dave Locher »

Beautiful guitar, and very informative thread. I was just last night wondering about hollowing out a sort-of arched top this way and today read this thread. Serendipity!

I think we (those of reading this thread) missed a question in there from Adam about pickups on such a guitar? I have a lot of experience putting different pickups into different styles of guitars because I am a total tinkering addict and can never leave anything alone. Every pickup I ever owned was, at one time or another, installed in just about every guitar I ever owned!
Although your answer was generally correct and a mostly-solid chambered guitar like that will not be prone to feedback like a true hollowbody guitar, potted pickups are a good way to go versus unpotted, especially with an f-hole of any kind. A guitar with that much open chamber will, based on my experience with high-gain amps at stage volume, be more prone to pickup squeal that a solidbody.

But other than that it's pretty much whatever you want. I've had patent-number humbuckers and Dimarzio super-distortions and Ibanez V-2s and Seymore JB humbuckers and no-name single-coil pickups all in the same semi-solid guitar and they all worked just fine but the single-coil squealed if I wasn't careful. (It was not potted.)
However, I put the V-2 into a true hollowbody once (replacing a patent-number Gibson humbucker) and took it out about 20 minutes later because the entire guitar howled and resonated in my hands anytime I went near my amp! It was just too much low-end and midrange gain. But the exact same pickup worked great in a heavily-chambered sort-of hollowbody.

Adam Savage
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Adam Savage »

Hi Dave,
Thanks for the informative reply :) I am not sure if the single coils I shall be putting into this guitar are potted or not (Bareknuckles, so I imagine they will be), but as it's unlikely the guitar will see a stage, then it shouldnt be too much of a problem even if they arent. I suspect I will replace them at some point anyway as I dont think their colour (mint) matches the afromosia, but thats a decision for later.
And at least for the first attempt at a hollowbody, I will not be doing any carving. Maybe the next one....

Cheers,.
Adam

Dave Locher
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Dave Locher »

You're welcome.
I don't know anything about Bare Knuckles pickups but I think the squeal would likely only occur with the '60s and '70s low-end pickups. In fact, now that I think about it I played a hollowbody Vox on stage with only minimal feedback issues and it had very microphonic pickups. You should be fine with those pickups in a chambered solidbody.

The biggest factor is actually your amplifier and any effects or distortion pedals you might use. My Randall amp will make most hollow guitars howl like crazy because it puts out tremendous low-end, but not much squeal. Higher-gain amps and/or distortion pedals will squeal like crazy but not howl. So it just depends. Even your EQ settings (especially how much treble) will make a big difference.

I never heard of the wood you are using, but when I googled it I saw that it is quite lovely. Sounds like a good start for the project.

Adam Savage
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Adam Savage »

Dave - BareKnuckles are a pickup maker from here in the UK, and make an extremely good range of all types (active aside).

Chad - Im sorry to be continually pestering you for questions, but I have one more before I (hopefully) have enough info to complete the guitar. How do you do the wiring without having an access plate? My internal routing is slightly different to yours in that it has a centre block, but otherwise simillar. I am planning on 3 single coils, a 5-way blade selector and a single tone and volume. The actual wiring diagram I should be ok with, but it is the manipulation I have reservations about. I havent yet decided whether to mount the pickups from the rear with an access plate on the centre back, or from the front with mounting rings, but I dont think either will affect the installation too much. Also, how do you wire up the ground wire to the bridge?

I truly appreciate your help with my build - photo's to appear once things are a little further on!

Cheers,
Adam

Bill Raymond
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Bill Raymond »

Chambering like this sure wastes a lot of nice wood. I would prefer to resaw a back off the piece, saw the rough interior chamber from the sides, then reglue the back to the sides and finish off with the router bit to make it all look neat.

Chad McCormack
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Chad McCormack »

Hi Adam. Ground wire to bridge is in the bridge bushing bore with a hole drilled through into the cavity. The region below the bridge pickup is completely open, so all components are soldered up and then pushed into the cavity below the bridge pickup. The f-holes allow my (slender) fingers access to steer the pot posts and switch levers into place. It's a little tricky, but doable without too much fuss.

Bill, I agree that a lot of wood is hogged out and transformed to useless chips and dust, but unless you plan on using the chamber cutout waste for other woodworking projects, I see the waste as six-of-one vs. half-dozen of the other. Perhaps I'm reading your post wrong and envisioning your process incorrectly.

Bill Raymond
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Bill Raymond »

Hmm, not knowing how you read my post I can't say whether you read it wrong or not <G>. I seem always to be able to use pieces of wood of that size for something or another, e.g. it could be used for head or tail blocks on an acoustic guitar, small finger planes, et c.. Be creative!

Jim Bonnell
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Re: Chad McCormack's "Equator" Semi-Hollow

Post by Jim Bonnell »

Chad, this is a great build. I was watching your's and Pete's as you posted them and like them both a lot. Now we have a third one posted and you guys are getting me charged up to try one. Where did you get the router bit you used for the binding slot? I haven't found one yet. Thanks and excellent job!

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