How To Use Wood For Cutting Arch Top.

[Hugo]

Hello all,

I've just decided to take the plunge and build a jazz guitar. Top and back will be cut from white Limba. Now I bought two nice slabs, but they're not perrfectly quarter sawn. I'll slice the blocks in two, and I'm now contemplating on how to put them together. A little drawing explaines more, I hope:

Top is the full block.

Second is the two halves.

Third is bookmathed (folded open), showing the curve-to-be..

Fourth is bookmatched and turned over, so the curve is it a different part.

Fifth is with the left part flipped over. I like this one.

Sixth and last is the same as the fifth, but turned over.

Which method would you recommend and why? It doesn't really matter what the result looks like (grain-wise...) 'cause it will get a solild finish. It will be carved to about 3mm (1/8") thickness.

REMARK: Dutch readers, please do not mention anything about this on the Dutch Gitaarnet Forum. I build this instrument to impress my girlfriend, and both she and me frequent the Dutch forum. So hush!

Thanks,

Hugo

Edited March 3, 2008 by Hugo

[Ptt-Guitars]

I would be inclined to go for the final example, the bookmatch (facing out both front and back). Its going to be stronger and possibly more predictable to carve, no point reinventing the process if its been tried and proven.

Good luck with it, is this your first build?

[Setch]

The fifth will reult in the most quartered grain orientation, relative to the surface of the archtop. Looks like the best plan to me.

Any particular reason you're using limba for the top? Spruce would be more traditional, and the optimal material for an acoustic archtop.

[Mattia]

What Setch said, second to last (or fifth one down, however you look at it). And also what setch said re: spruce top.

[erikbojerik]

Fifth.

Spruce.

[Mattia]

One more comment: 1/8" is awfully, awfully thin for an arched top instrument. Your average archtop (acoustic) is about 1/4" thick at the center, thinner (maybe down to 1/8", usually more like 3/16") at the recurve. Back (hardwood) is often a touch thinner, but not that much thinner. You're asking for too much feedback/movement if you go that thin, IMO.

I shoot for between 5 and 6mm for my carved electric instruments (carved inside and out).

[Hugo]

Thanks for the replies, guys. OK, number 5 it is!

I will use the Limba to see which result I get, and don't worry about the thickness: have wou ever looked inside an es335? It's fairly solid, I will make something similar taking up the forces. I think the body construction will be a nice mix between guitar building and model aircraft construction (other hobby).

And this certainly isn't my first build, but it will be my first non-solid body. Although I built a Thinline Tele, but that doesn't count, 'cause I cheated: cut the body and cavities from solid and then glued 1/8" maple ply to the front and back. Worked well, BTW.

I think I will route out the back inside first, in steps, then cut and sand 'till I get the complete curve. Then turn the lot over and repeat the procedure on the outside-side. This way I allways have a flat surface to clamp.

All hints and tips are welcome...

Cheers,

Hugo

Edited February 27, 2008 by Hugo

[Setch]

Hugo,

1/8" is very thin - stick with 1/4" or you *will* have a structural failure. Maybe not today, maybe not tomorrow, but certainly the first time the instrument gets bumped. 335s and their ilk may go thinner, but only when they're using pressed, laminated (plywood) tops. Going that thin with carved solid wood is a recipe for disaster because of the way carving creates short grain, it's significanlty weaker than a flat section of solid wood of equal thickness.

[Vinny]

Buy the book "Making an Archtop Guitar" by Robert Benedetto, he show all the steps, specs and templates with needed jigs to build it right. -Vinny

http://cgi.ebay.com/Making-an-Archtop-Guit...7QQcmdZViewItem

[Mattia]

Listen to Setch.

A center block helps, but it's about the runout; a pressed, laminated plate has zero runout AND is stronger because of the lamination, so 1/8" is fine. Solid wood? Go thicker. Much thicker. Sure, 3mm thick can be OK, but even on a fender-style thinline, I'd go for at least 5mm, if not 6mm (which is what Fender does, BTW). They're electrics, and most folks don't treat them as gingerly as acoustics (which while they do have 3mm backs and tops, sometimes a little less) are a) a lot more fragile, have bracing that means there isn't a huge unsupported arc anywhere on back or top. Also, the act of arching the top and back (radius dishes) provides additional stiffness. And no short grain like you get with carving.

[Hector]

you should`ve sliced the block at an angle. that way, you would`ve ended up with two wedges. the way archtop (cello, violins, etc) top and back woods are supposed to be. the wood would be thicker where you need it to be, and thinner on the edges.

[Hugo]

OK, 5mm will be the goal. I know about slicing the wood at an angle, but it was way to thick to start with. Cutting at an angle is saving wood, starting with a thinner log.

Hugo

[Mattia]

Supposed, shmupposed. It's tradition, the way to get split, perfectly quartered, no runout wood and waste as little as possible.

Personally, given the way I carve my tops (indexed around the edge with a router, then carve away), wedges are a pain to carve compared to flat pieces. They're also a pain to join (relatively speaking) and clamp, at least, more so than block billets.

[Hugo]

OK, today I sliced the 2 logs. Manually. 240mm wide, 600 long. Why isn't my bandsaw just a fraction taller?? Anyway, it's done, and I'll now smooth them out and join per 'no. 5'. Just went into my parts cabinet and pulled out 2 P90 pickups. I think they're going on this one, with a simple 3 position switch and one volume pot. I like it simple.

Hugo

[Mattia]

I like your style.

(also, feel free to trek up this way if you need some stuff sliced that your bandsaw can't handle. At least, if it's 26cm wide or less, anyway...or was it 24?)

[foil1more]

Yes, P-90's and a hollowbody sound very good. the lead guitarist for The Strokes almost always uses an Epiphone Riviera (hollow with P-90's)

[IWishICouldShred]

No tone knob on the jazz box?