The Soundboard

The soundboard isn't complete yet so I don't know whether what I did worked. But here it is so far.

I started with five pieces of rough-sawn sitka spruce, 1/4" thick by 4" wide by about 64" long, which I got by mail order from Zuckermann for about $160. I'm really dreading the hand-planing that it will take to finish it, so I cheated a bit and put it through the thickness planer that I rented for the basswood (for the case), to bring it down to 3/16" and make it smooth, to keep the hand plane from clogging later. I didn't want to go all the way down to 1/8" though, since the pieces are unlikely to end up perfectly flat so I need some extra material so I can plane away the little steps that people said I'd probably end up with at the joints after gluing (they were right).

Rough-cut sitka spruce.

Rough assembly of the soundboard was quite a bit of work. People on HPSCHD-L were very helpful with this.

Jointing

I don't have a power jointer, and I couldn't find one for rent. Evidently this is one of those things that people get religious about, arguing over whether hand tools or power tools are better, but I really had no choice, since power jointers (nice ones anyway) are so expensive. So I bought a beat-up old Stanley No. 8 24" jointing plane off of eBay for $66, got a Hock replacement blade for it from Lee Valley, and sharpened it using a honing guide, and sand paper (I got up to 2000 grit from the local Sherwin Williams auto paint store) tack-glued onto a sheet of glass.

I was a bit afraid of trusting an old antique tool for this, until Andreas Kilstrom (on HPSCHD-L) pointed out what I suppose is obvious to others but not to me, that if your plane is warped and shoots (say) an 85 degree angle on one edge, all you have to do is plane the matching edge upside down to get a 95 degree angle and you're all set, it'll add up to 180 degrees and your soundboard will be flat. So that's what I did.

Not much to it -- a couple of 2x6s to support the plane and the work piece, all clamped to a 4x4 for stability (I moved relatively recently and haven't set up work benches at the new house yet).

It took a bit of practice to figure out where to push on the plane to fix which kind of curvature, but after lots of work (during which I discovered that my 48" ruler's edges aren't quite straight) I got the facing edges to match each other nicely.

Gluing

I would have done this all wrong, but Den Ciul at Claviers Baroques told me about a really neat method of edge-gluing the soundboard pieces using masking tape. Start with the pieces lying flat on the workbench (or floor), with the "good" side (the one that you want to look good) up.

Step 1 -- tape across the joint, with the boards not quite flat.

Step 2 -- carefully press everything flat. This will draw the joint tightly together.

Step 3 -- tape along the joint.

Step 4 -- fold joint back, to release tension and expose the gluing surfaces.

Step 5 -- apply hide glue (in the cup, which has been sitting in a pot of 145-degree (F) water which I just took off the stove) to the exposed edges. I've propped the soundboard pieces between some 2x6es to make the gluing edges point up.

Step 6 -- flatten the joint again, and apply weights or clamps to hold it as flat as possible while the glue sets.

I'm new to hot hide glue so it's been a very intense experience. It's really picky about temperature, so it needs to be heated in a double-boiler where you're keeping an eye on the temperature of the water bath (approximately 145 F). Also, the working time is extremely short once it's out of the glue pot (uhh, yogurt cup) and on the work piece. Once I got half a clue I started doing the gluing in my bathroom, because it's big enough for the soundboard but still small enough that a little electric heater can get it close to 100 degrees F in just a few minutes, which buys you a little time with the glue.

Some of the stuff I've read suggests that hide glue needs much less clamping than what I'm used to (which is Titebond), so I may have gone a tad overboard with the clamps, but it doesn't seem to hurt so what the heck. I cut slots into the edges of little 6" lengths of 1x2 pine to stop the F clamps from totally screwing up the outer edges. This helped a lot (and kept the clamps from slipping off) but even so, the edge was a tiny bit deformed, so there's no point in doing the jointing for the next joint until after you've finished gluing up this one.

As you can see in the picture, the soundboard flexed a bit while I was clamping, but it straightened out again when I took the clamps off. The hide glue makes a very stiff joint. Sandwiching the glue joint between two 2x6es (chosen for their straightness) made the joint nice and straight. Luckily, hide glue does not stick to masking tape, not even to the sticky side (although spruce sure does -- so you have to be very careful when peeling it off so you don't rip big splinters out of your nice new soundboard), so adding a strip after you close the joint will prevent the 2x6es (or whatever you use) from sticking.

The finished assembly looks pretty nice, from a distance anyway.

I was tempted to try to save time by gluing together more than one pair of boards at a shot, and then stick my progressively bigger pieces together as I went. But I figured this might be a bad idea, because a little clamping might persuade a flimsy 4" wide piece of spruce to fit against an edge that isn't quite perfectly straight (in spite of my best efforts while planing the edges to match), but an assembly 8" wide would be a lot more rigid so my mistakes would haunt me all the more. I don't know if this was good logic (maybe no amount of mismatch should be forgiven) but I don't see how it could hurt to do just one joint per gluing session.

Planing

This is the part I'm really dreading. I bought a ratty old Stanley No. 4 smoother off of eBay for $15 and I'll be working on fixing it up a bit for when the big day comes, but I've had really rotten luck before with trying to smooth wide open spaces with a hand plane so I may try to cheat (i.e. belt sander). Luckily this won't happen for a while, I'm taking the advice from David Jensen's web page and leaving the half-finished soundboard to mellow in a corner for the months or years that it will take me to build the case and action.

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