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Semi-hollow Build Project


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Hi,

Just bought a one-piece mahogany body blank on e-bay last night and would like to use it for the bottom of a semi-hollow strat-style guitar that I'd like to build.

Are there any "rules of thumb" with regard to the thicknesses for the tops and bottoms of these type builds?

To keep the guitar in the 1 3/4" thickness dimension that I see commonly used for solid body builds, I figure I'll have to plane down the bottom in order to accomodate the top's thickness. I'm not planning on going for a carved top--I figure I'll have enough trouble figuring out how to laminate a flat top to the routed mahogany bottom anyway.

Instead of going wth the traditional Strat shape, I'd like to use the body shape of a JazzMaster. Although the body will be that of the JMaster, everything else will standard Strat--with the exception of a piezo type pickup in the bridge that I'd like to add for some accoustic versatility. Anyone have any tips on drawing this so that I can make a template? I'm not so good at freehand drawing---traciing the real McCoy or using a computer drawing would be best for me.

Anyway, thanks in advance for any info shared.

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You should make yourself a template that has both an outer edge (for routing/sanding the body shape) and inside, has the shapes of the chambers that you want inside the guitar (one of which is the control cavity). Plane the mahogany blank to the required thickness, screw the template to the blank (countersunk screws located where two of the pickups will be), then rout out the chambers first before cutting out the body outline.

Best to (1) make your template out of 3/4" MDF or birch ply, and (2) remove most of the wood with forstner bits on a drill press before routing off the last little bit, and (3) incorporate the shape of your neck pocket into this template as well.

The thickness of wood you leave on the back is a matter of personal preference, but I'd shoot for no thinner than 1/8".

THEN you can glue down your top plate. You'll need another template for your pickup cavities (and trem if you have one); the template for your neck pocket is already formed in the mahogany underneath (just make sure you remove any glue squeeze-out when clamping down the top).

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All he says is good, but I'd freehand with the router. It'll all be covered when you put on the cap anyway......

watch out for the belly curve on the back of the strat body.

obviously this will hit the inside routing unless you plan ahead!!

if yopu're using a LR Baggs X-Bridge you don't need to worry too much about hollow bodied resonance. I have one aon a solid strat and it's great!!

as for thickness, I took the back of my last "carved from a block" hollowbody to 3mm on a vertical mill

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I do it like Erik, mostly, although I'm 'good enough' with a router to freehand the edges after I've drilled out the excess with a forstner. Much easier/faster than routing it all. As for belly carves, well, plan! On my latest I carved the inside of the belly carve as well (gouge, scraper to finish up), mostly because I'm a dork and I felt like it:

chamber4.jpg

I always cut the neck pocket after the body's together and complete, match it to the neck.

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Hi all,

Thanks for the advice posted last week. With the mahogany body on its way, I went out and made a template this weekend--and I got some very helpful advice from an unexepected source: my 11 year old daughter. She saw me struggling with transfering the CAD drawing, at scale, to something I could trace out on the template. She came up with the idea of using the overhead projector to trace out, here's what we did:

Body Template

Template was created by downloading CAD drawing and printing it out on a 8.5” X 11” transparency. Using an overhead projector, CAD image was projected onto a piece of cardboard construction paper that was pinned to a wall. Paper was pre-marked with a straight line that was then matched to the center line of the projected CAD image. Projector was adjusted until projected neck pocket outline was as close to actual dimensions (3” X 2 3/16”) as possible, with center lines matched.

With neck pocket scaled correctly, guitar image was then traced onto construction paper, then cut using an exacto-knife. Cut paper image of guitar was then laid onto 3/4” thick slab of birch plywood, traced and cut using a band saw. Belt sander and block sander were then used to smooth out edges. Template edges are not perfect I may work on them as time permits, will need to get a drum sander set up for my drill press though.

Check here for a pic: http://www.geocities.com/savespark/GuitarBuild.html

Next step will be to figure out how thick the top and body will need to be--I have a neighbor with a 12" planer who'll happily let me use it. One small thing though with using this planer, the max width of the template at the "toe" of the guitar is about 13 inches. My neighbor said we may be able to the turn the guitar as it feeds though the planer--this of course means that the body and top will need to be cut prior to planing, instead of just planing down the raw wood. Any issues with this that we should be aware of? Also, turning a piece as it goe through a planer to make it fit--any issues there?

How does this sound for top and back thicknesses: Top = 3/8", Bottom = 1 3/8" I figure with a 3/8" top, I'll be able to shape an elbow contour into the bottom left part of the body.

I'll be ordering the top shortly and will be getting some templates for the neck cut out, pick ups, trem and contols.

As always, I'll take any insights that you may have.

Thanks

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OK, the wood's in and looks pretty decent--at least to me it does!!!

Here's a pic:

http://www.geocities.com/savespark/GuitarBuild.html

As for next steps, here's what's going on:

Will stop by a local exotic wood place tomorrow to find out about a top to laminate onto the body. In doing research on-line I'm finding that this may something I might want to reconsider--here's why:

1. Expense--this top wood, especially if it's got a bookmatched grain pattern, is way expensive. I'm not so sure that "learning" about guitar building on high end materials like this will be very productiive nor is it smart.

2. Top Contouring---I'd like to have an elbow cut on the top of the guitar (looks and comfort) but am not too keen on trying to bend the top a-la "drop top binding" that I've seen around the net. Might go a bit thicker on the top (3/8") Then sand it down at the elbow. Also, I'd leave the elbow area in the body un-routed. We'll have to see about this though.

Although I could simply abandon the semi-hollowbody approach that I started with and try for a solid body with the wood that just came in--- I also don't want an anvil hanging off my shoulder, and this block of Mahog is heavy!! My current guitar IS an anvil and I'd like something light to switch to for a change.

So here's a question for you experts:

Ever hear of anyone hollowing out a guitar body from the back? Maybe I'm the Forest Gump of guitar builidng and don't know better, but it seems to me that I could take my block of mahogany and could clear it out from the backside, leaving a strip down the center for pick ups, bridge and trem. I could then make a couple of lightweigt panels to place over the cavities. This would eliminate all the trouble of trying to lam a top on a the face of the body. The wood removal would keep the axe light and maybe even give it somewhat of a hollow-body tone.

My reason for asking this question is based on the fact that my present guitar, a 1981 Gibson RD Artist, has a major rear cavity that has a recessed plastic cover over it. This guitar was one of the first to have "active electronics" in it and the cavity in the back is where all the electronics boards, etc. are.

Anyway, I'll see what the exotic wood place says tomorrow. Then I'll figure out what I'll be doing on this thing this weekend.

Thanks

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Ever hear of anyone hollowing out a guitar body from the back? Maybe I'm the Forest Gump of guitar builidng and don't know better, but it seems to me that I could take my block of mahogany and could clear it out from the backside, leaving a strip down the center for pick ups, bridge and trem. I could then make a couple of lightweigt panels to place over the cavities. This would eliminate all the trouble of trying to lam a top on a the face of the body. The wood removal would keep the axe light and maybe even give it somewhat of a hollow-body tone.

Doesnt sound great to me but it will work. To me that seems a lot more work than glueing a flat peice of wood to a flat piece of wood with chambers in it (which you can effectively treat as another flat piece of wood).

you have the option of making as many holes in the guitar as you want as long as you leave the centre section intact - but think about what looks good as well and what you can live with, personally i would struggle to live with a guitar with large plates over the back when there are neater ways to achive the same thing that are not that difficult to do. I do love the old RD's but not from the back - at least there plates had a purpose!!

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Thanks WezV, I think you are on the money with your assesment re looks vs. functionality--but the big plates on the back of the guitar WILL have a purpose, they'll keep me from becoming sway-backed!!! Just kidding on that one, I do get your point and appreciate the well thought advice.

Made a visit to the local wood guy and.....maybe the traditional top and bottom approach won't be so bad afterall--here's the latest:

I bought a piece of birdseye maple for a very reasonable $45 yesterday. Its dimensions are 50" X 8.5" X 1". I figure I can do one of three things with this:

1. Check into gettting it re-sawn and planed--3/8" bookmatched would be ideal if it can be done.

2. Cut it in half, then have it planed down to 3/8" (lots of waste!!) and try to join it with some kind of interesting grain pattern showing.

3. Ruin it and not give the wife another "stupid husband" story to add to her collection.

While planing down the top wood, I would also have the body blank planed down to 1 3/8" so that the total "sandwich" achieves a thickness of 1 3/4".

Got some calls out to some local woodworking / cabinet makers in the area (Annapolis MD, USA) to see about the shaping. I would really like to know if the re-saw option is feasible. If so, I'd have enough wood for two tops AND it would really look good.

Will also check with a kindly neighbor (only accepts beer as payment) about the use of his planer. Will post results, hopefully, soon.

Thanks

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Hi Everyone,

Here is the latest re the hollow body J-master build:

Had the birdseye maple re-sawn and planed down to 5/16" then had the Mahogany body blank planed down to 1 7/16", so now I have book-matched top wood (enough for two tops) and a body that I can start hollowing out.

Here is a picture of the materials so far:

http://www.geocities.com/savespark/GuitarBuild.html

Next step will be joining the maple, then using the template to cut out the guitar top and bottom.

I'll post pics with progress soon--hopefully.

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OK, here's the latest re the hollowbody Jag build:

The bottom wood is almost all routed out and the top wood is glued up.

See pics here: http://www.geocities.com/savespark/GuitarBuild.html

Couple questions for those in the know:

1. Re the center strip---is 4.25 too wide? I arrived at that measurement by taking 3.728 and adding 1.0 inches to it. --.5 on the right and .5 on the left. I read in a post in this group that you should take your widest element and add .5 to each side. I'll going with an S-S-H set for the pups so I doubt that they will be wider than 4.25". If it turns out that my strip is too wide, I'll take a smaller Forstner and put some more holes in.

2. Re the chambers, would it be reccomended to connect them all together with a small route? Although I'm more interested in reducing weight than trying for an accoustic sound, I thought I might let some air travel around the inside of this guitar. Thoughts on this would be appreciated. Note though, that I do want this guitar to sound like an accoustic, but not all the time. I'd like to be able to use an X-Bridge to go from a Strat Sound to an Accoustic sound when needed.

3. Should I simply clean out the area in the lower right of the body, i.e. no honey comb? With the book matched birdseye face I'm planning for a rear route for controls. Any issues I should know about ahead of time with regard to the rear route? Do I have to leave anything inside this guitar for the controls to mount to? I seem to recall that they will mount to the underside of the top--I'll do some research here before I proceed.

4. Before lamming on the top, I'm pretty sure I'll need to drill or route cable paths from the controls cavity to the pup-stack. Any advise would be appreciated here as well---Hate to close this thing up and find out I've go no way to run wires.

Anyhow--thanks to all who have been following this, feel free to reply.

Thanks

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I'm sure it's too late to do something like this. I plan on doing multi-chambers like this on a future 6-string fretless build. It will reduce the weight without reducing too much (body weight is important for balance in ERB's). Of course I will continue to experiment until I get the right results.

th_fretless3.jpg

Click to enlarge!

I did another build with 3 seperate chambers and went completely through the electronics cavity - the pots would simply mount onto the top, which would be 1/4" thick.

Project711.jpg

If you did laminate the top to the body before routing any channels for wires, you would not be harming yourself. You could still drill holes at an angle for the wires to run. It would be much more simple to route the channels and not have to worry about this at a later time.

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Thanks for the input Bilious and Jon, I do appreciate it.

Jon--nice pics of your bass, hope it turned out for you. What you did there is exaclty within the spirit of what I am trying to do--create a truly unique instrument that will be fun to play and maybe will even sound unique as well. Re the through cavity for controls, I had thought about that but will probably just do a standard rear-route since I can get templates for the cavity and cover recess cheap online. A custom made back cover for controls might just be one of those things that I SAY I'll do, but never actually complete. If this guitar get's that far and is playable--I'll be too busy messing around with the sound and the cover will be left hanging.

Here's a question for you: When you lammed the top on to your bass, did you add an elbow countour on the bottom left of the face? I've seen this done on another guitar I own and, in this case, the body width was taken down to 1 inch (.75 inches removed) at its outside most edge. This of course was done on a solid body guitar so the shaping was no big deal (other than making it look nice!) For semi-hollows like ours, we've only got the top thickness to work with and in my case, it's 5/16th of an inch. I would like to have some contour for this area of the guitar, if not for actual comfort, then simply for looks is fine. I was thinking of NOT routing out any cavities under where this contour will be so that th top, however thin it may end up, would have something under it. Any thoughts or prior experience on this would be appreciated.

Bilious---re the full-through route out and the back panel idea. I had thought about that as well, but again figure going the easy route will be best for me at this point. Besides, I'm pretty sure that I'm hooked on building guitars now and will be making another one when this one is done. Maybe that top wood will come in handy for Axe #2 or something coming later.

Will (hopefully) start on the top cut tonight, will post pics as I go.

Thanks

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Here's a question for you: When you lammed the top on to your bass, did you add an elbow countour on the bottom left of the face?

No, not yet. I ran into a whole new deal of problems that involved me removing one top, so I have to remove the other top and re-do the veneer and top. I'm waiting until I get my vacuum pump system set up to do the top so I can get that done properly and accurately.

Will I be doing it? Possibly for aesthetics. I play with my basses high with my arm resting over the waist, so I don't use the arm rest area like I would on a guitar. If I were to go this route and shape an armrest, I would most definitely need a thicker top. Just make sure to check your work frequently if you are going with an armrest, you don't want to remove too much of the top and have a hole showing.

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I'm waiting..........so I can get that done properly and accurately.

Now THAT's an interesting concept---I'm stringing rubberbands across mine already and twanging them just to hear what it sounds like (just kidding of course) Wait and do it properly???!!!! That might be the best advice ever offered on this forum.

Went ahead and glued up a second top last night, since I wasnt' too thrilled with the first one. I used my workmate as a clamping base and think that it might have been the source of the problem---Since I want to start cutting the top asap, I didn't wait to get the proper clamps and just went for it with what I had.

Might pay the price by having to re-do it all tonight---we'll see.

Thanks

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I've been through a lot of gluing techniques. I could use a few to get some veneers / tops glued, but I'm tired of the long setups and use of time to do this stuff. I've got other solid body projects and other refinishes that I'll be working on until I have the cash for a vacuum pump system. So it's not a matter of only wanting to use one technique (vacuum) - I'm just trying to spend my time as wise as possible.

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OK here is the latest re the build---pics are here:

http://www.geocities.com/buildaxe/

Glued up and cut out the top, then shaped it to the body using the drill press and drum sander. Didn't go overboard on this since I'll be doing a lot of final shaping later.

Hollowed out the controlls cavity in the body from the top. Once I figure out how everything will fit inside, then I'll cut out the back. Since I'm going with an LR Baggs X-bridge (piezo pickups for accoustic sound) + a pre-amp, I'll have to see where everthing will go and if I'll have enough room before I glue the top to the body.

Ordered the neck from Warmoth today. It's a standard Strat replacement neck, mahog with kingwood fretboard Gotoh SG38 machines (chrome), stainless steel jumbo freights and a graphtec nut. They'll set it all up and I'll finish it once I piece everything together.

Now I've turned my attention to pickups. Since my group plays a lot of different types of music I was thinking of going for a rock and blues type sound form the mags--how does this sound?:

Bridge Magnetic PUP==Seymore Duncan JB JR Humbucker

Neck and Middle ==Seymore Duncan JB JR single coils

I went online to their site and listened to a bunch of tones from a bunch of their PUPs and these two sounded the best to me. I am still researching this, so any insight any of have would be grealty appreciated.

It'll be about a week or so until the neck gets in so I won't be doing too much untill I get it. Although I could route out the neck pocket and the trem cavity in advance, I figure I'll wait to see exactly what I'll be delaing with--I am actually planning on routing a test pocket just to get comfortable using the template etc. I also don't want to get the scale length messed up by trying to cut it out before I have the neck installed.

Anyway, let me know what you guys think re pick ups.

Thanks

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Hi to everyone following this build, for the lates pics, click here:

http://www.geocities.com/buildaxe/

To summarize, here is the latest:

Third try at glue up of the top yeilded satisfactory results, I went ahead and cut out the guitar shape in the top and used the drum sander to match it up to the body.

I also went ahead and routed out a fair amount material for the controls of this guitar. I didn't take it all the way through the back side of the body since I wanted to make sure I was going to have enough room for everything. Note that I'll be going with an LR Baggs X Bridge with a pre-amp and will most likely go with a 4 knob arrangement for volume and tone control. I figure on going with the Strat standard 3 knob (5 way switch) set up for the magnetic pick ups and use a dedicated volume pot for the X-Bridge. Once I order all of this and get it in, I'll lay it out inside the guitar, before the tops gets glued, and will then cut the back controls opening.

I ordered the neck from Warmoth a couple days ago. I went with a Warmoth Pro, Kingwood on Mahogany, with stainless steel jumbo frets and a graphtec nut. This should be in next week, so I won't be doing too much real work until it gets in and I can route the nect pocket. This weekend I hope to try routing a test pocket in some leftover wood so as to get comfortable and familiar with using the template.

I've also been looking at magnetic pick ups and have come up with the following:

Neck = Single coil Seymore Duncon JB Jr.

Middle = Single coil Seymore Duncon JB Jr.

Bridge = Humbucker, Seymore Duncan JB jr.

Let me know what you guys think of these choices. I used the tone comparison tool on Duncan's web site to listen to a bunch of different pick ups and these all sounded the best to me for what I like to play.

Any comments or suggestions here would be appreciated.

So anyway, I'm waiting on the neck and will resume working once it is here.

have a great weekend.

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I think it's looking pretty good so far. I like the Jaguar shape a lot. The one piece of advice I have for you is never to try to joint anything with a hand sander. As you've found, it's not a particularly effective method. Find a shop that'll give or sell you ten minutes on their jointer or buy a bench plane and learn how to use it. Either way, you'll get better results in less time. Once you've used a hand plane a bit, you can get an invisible glue line on a body or top in a minute or two. You can even use a long, flat block with sandpaper on it. But using an electric sander isn't a very good method.

Actually, if your table saw is pretty good, with a good (new/sharp) blade you can get a pretty invisible glue line straight off the table saw. You have to have a jig or fence in place that lets you push the piece straight along the blade though, any wandering and you have to start over.

On the subject of your pickup choices - the JB jr. is a single coil size humbucker, but is still a humbucker, while the humbucker sized version is called just the JB. Did you mean to have a JB jr., JB jr, JB guitar, am I misunderstanding? It's not something I would do, but if it's what you want, go for it.

Edited by jnewman
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