Scraping the recurves: Easy but tedious.

Since the start of this project, I've been mystified and a little intimidated by "scraping the recurves" on the tops and backs. By introducing a concavity around the rims, the tops and backs are thinned, and become more resonant. I left a flat area of between 1 and 1 1/2" inches all around where this concavity would go, then hoped for the best until the past 3 days, which I spent scraping and scraping and scraping.

Truthfully, I haven't had a lot of experience with fine, thin card scrapers. I've planed and sanded and cut, but light scraping just hasn't been part of my regular woodworking routine. Especially not using a curved scraper, which I wan't even sure I could sharpen well/

But it turned out fine. I'm not sure my scraping achieved a tone like Bob Benedetto's, but the bodies are much more "alive" now to the touch. Taps are deeper and last longer.

Before I could scrape, I had to install little 1" bone pieces for the tailpiece wires to bear against. Fussy work with a sharp knife and a 1/4" chisel. When I ground down the bone to fit flush on top, the shop smelled like a dentist's office.

Scraping one of the backs. I reground a scraper iron from a tool I never use to the curve  shown on the plan, then spent three days using this tool an another "french curve" scraper, which I sharpened about a half dozen times. Each push or pull of the scraper brings up a tiny curl which I'll guess is no more than  a thousandth of an inch thick. The good news is that when the scrapers were sharp, they didn't tear out grain at the upper or lower ends, where it was completely cross-grain.  I'm a scraper fan now, but I won't underestimate the time it takes. 

While I was scraping, Spring happened, and I was able to work outdoors for most of the process. The two scrapers are shown here. I'm amazed how much wood I actually removed. 

One of the bone pieces after the recurves were in. 

With the recurves scraped in and all surfaces rough sanded fair, the bodies of the guitars are concluded, except for a big mortise in each for the neck, which I'm not going to tackle right now. In this photo, you can see the slightly wavy, asymmetrical match of the two back pieces for one of the guitars, which is going to look pretty nice, I think. On to the necks!

Cheapskate router setup for nice wood bindings

I'm making two guitars, not starting a new career. And, let's face it, I'm pretty cheap when it comes to buying one-trick tools. But I want things to be, well, just so. So when I booked up on cutting the channels for the bindings, I was a little dismayed to find this router bit set and this router cradle as the "best" way to cut perfect channels for the wood bindings I wanted. Buy them together for $278 plus shipping.

I've been cobbling together router setups for 35 years, and I can't for the life of me understand why you would want to jack up the guitar in the air and then hang the router even higher in the air on top of that.

Here's what I did instead, with some scraps of poplar and a mix-and match of router bits and bearings on hand

Basically, I used my router table with a scrap of 13/16 poplar surrounding the bit, then taped same-thickness scraps of poplar to one side of the face I was cutting. The way, both sides would always be the same height off the router table, which means the same depth of cut.  Then, when one side was cut, I swapped the taped-on scraps to the other side and finished up. 

Ready to start the first cut. I'll admit I was nervous. I sharpened the router bit with a tiny diamond file. But I couldn't see what damage I could do, except for tearout, which I addressed by going really, really slowly around.

Closeup of the first setup.

After the first channels were cut on the tops, where there is a 2-part binding, I went around tops and backs for a second channel for the outer curly maple binding to cover the end grain of the tops and backs. Same idea, different router bit.

I was really happy with the result: clean, no-cost binding channels. Take that, Stewmac!

I found a nice 4' chunk of curly maple at woodcraft for $3, because it had a huge hole in the middle of the board. Fine with me - I just cut strips about 3/32" x about 7/16" on the tablesaw, and scraped them flat. I had to buy a new blade for the saw, though - even my mildly used 40-tooth blade caused blowouts in the grain. A new 60 tooth blade did fine, then I scraped and sanded the strips.

70 degrees out! I was able to work at my outdoor workbench for bending the bindings. What a difference bending the maple vs. bending the mahogany; curly maple falls apart if it's wet, and the mahogany doesn't bend if it's dry! In the photo, the first maple strip has been bent, and is immediately ready for installation.

Bending the second curve on a cutaway-side maple strip. The best technique proved to be slooowwwly pushing  the maple around the hot iron, dry. I used the smaller-diameter "upper level" pipe (see prior photo) for the first tight cutaway curve, then the lower-level larger pipe for everything else. No springback on this stuff at all. The little mahogany strips bent more easily, with just a little spray spritz of water which made steam.

Superglue! I went about an inch at a time, pushing the bindings in, seeping a little glue in, spraying accelerator. Took about 10 minutes a side. Tape wouldn't have drawn it in tight enough, and there was no way to clamp. The guitar bodies looked dishearteningly ugly at this point.

For the bottom joint, I overlapped set the first strip in a hair long, overlapped the second, and used a sharp 1/2" chisel to put them together. Worked well.

Thank you, Miles! A friend left his Fein Multitool here several years ago, and hasn't bothered to pick it up. This is the only time I've used it, I swear. Had to buy a new velcro pad and some Schliefblatter for it, though. Working outdoors again - less mess in the shop. I was really happy to see that superglue disappear. Next step, not shown here (my wife needed the camera at work) was two days' work scraping and sanding the sides flush again. Thorny work on the inside curves.

Bindings in place, rough sanded. Next little step, inserting the bone piece at the base of the tops where that tailpiece adjusters go, then scraping the recurve on tops and backs, which should be interesting.

The Big Glueup: tops, sides, and backs

The guitars have gone from 2D to 3D... from parts to bodies. Yay!

Last look inside. It's sort of a shame nobody will ever see these fittings again. 

Glueup! Top, sides, backs. TRhis was pretty frantic, working quickly to get the glue spread before the "open time" expires. I use Titebond III for this, partly because the open time is a little longer than II. For this glueup, I made a special rim-wide clamping caul, which is on the top of the sandwich, and a special little clamp to pull the cutaway area together.

Cutaway clamp. Just some scraps of plywood, a 3/8 carriage bolt, and the hand nut from the original carving jig, which is the bottom part of the sandwich.

Sanding the sides flush and fair. The body on the right is done, the one on the left in progress. It was a full day's work to sand the sides. The sides themselves are only about 5/64ths to 3/32" to begon with, so I was really wary about using power tools here. I made up some wide sanding blocks of 100 and 150 grit paper, and carefully leveled the whole perimeter. There were lots of subtle "flat spots" from the side bending, which needed to be smoothed out - you'd see and feel them if you didn't. Also, the sides need to be perfect now because the next step - binding - requires a fair curve to follow. Both bodies turned out fine, although my arms were aching and my hands hurt.

Sanding the tricky part. I made several half-round sanding blocks, in different grits, to sand and fair the inside curves. Even so, it was difficult, because all the sanding had to be with the grain of the wood, although it was tempting to sort of saw away sideways in these spots.

Congratulations, Brendan! Tag inside one of the guitars. 

Blocks, stiffeners, linings: fitting out the sides for gluing

Sorry for no post in a while - but I took about 2 weeks to raise some cash by building a 17 foot wind tunnel for a friend who manufactures anemometers. I had to build and deliver it in two parts, because I couldn't fit it all in my shop. Take a look, and you'll understand.

But now I'm back on the job.

Once the sides were bent, and the linings were cut, I installed blocks, vertical stiffeners and linings to the sides, to get them ready for the big glueup. Here's how it went:

Adding neck and tail blocks. I was amazed to find I still had some 3" thick chunks of Honduras Mahogany in my shop from about 20 years ago, when I made garden furniture out of it.  I brought the chunks up here from New York.  It was perfect for making the thick neck and tail blocks, which  I glued up in the main clamp to fit the sides together.

I goofed, but it's OK. I bent one of the sides so that it fell about 1/8" short of meeting the other side in the butt joint at the top. So I had to scab in a filler piece cut off from trimming one of the other sides. Instead of just adding about 1/8" to fit, I cut a little bit more off the short side and added about a 3/4" piece to fill. BUT no problem - the "extra seam" will be invisible, hidden under the neck when it's assembled. If this is the worst mistake I make, I'll consider myself lucky.

Gluing in sections of kerfed lining to the inside edges of the sides.  By a stroke of serendipity, I had a relatively clean "indoor" job I could do upstairs in the house during evenings while the shop was in shambles from building the wind tunnel. I added vertical grained basswood stiffeners to the sides where indicated (you can see one just under the tip of the brush) and segments of kerfed lining in between. This was nice, sit-down work.

Kerfed lining sections clamped and drying. I used little spring clamps on the ends and clothespins in between. 

Adding filler strips. To make the best possible uninterrupted glue joints between the sides and the tops and backs, I added small, tapered fillers  over the vertical stiffeners, in between the strips of kerfed lining. When these were dry, I pared them down to the same profile as the linings with a sharp chisel.

Leveling the edges with a "sanding paddle." I spray-mounted sandpaper to one end of a wide flat stick, and rubbed the "sandy part" over the kerfed linings, little by little, until they were flush with the sides. Careful work, but satisfying when it was done.

Using the sanding paddle trim and level the edges. Neck block, sides, vertical stiffeners and kerfed linings all cleaned up and level!

Ready for gluing the tops and backs. Last good look at the inside.