Building a Ukulele from a Stewart-Macdonald Kit

Part 4: Attaching the soundboard

 

 

Once the glue for the linings has set, you need to knock off any glue squeeze-out and trim down any place where the linings came up above the edge of the rib. To do this while keeping the top edge of the rib/lining assembly even all around, I use a sanding board. This is just a piece of plywood with adhesive-backed sandpaper attached to it. I jazzed mine up by screwing an old push-block to it that came with a jointer (it was my second jointer -- I still have three of these and use them, well, two at a time, when using my jointer.)


With the linings and ribs flush and level all the way around, it's back into the mold. The turnbuckle shown here keeps the ends of the rib against the ends of the mold and helps to maintain the shape while you proceed with the following steps. Just a speculation here...what does the tailblock do when the rib is bent from a single piece as this is? The headblock guarantees the joint at the top end, but there's no joint at the tail. 

 

As you will see in the following steps, I'll be pushing the body around a lot. These registration marks let me adjust it back when it slips around.

 

The springback in the rib caused the waist to be too wide for the soundboard (the "top" or "table", that is, the front or the part with the soundhole in it.). Clamping it as when installing the linings wouldn't work, since the top has to go under the clamp. I've rounded the ends of two of the wedges I used back in chapter 2, and screwed them down to the mold to hold the waist in. 

 

While pushing the body around to get the waist in, I was continually moving it off-center, as revealed by the registration marks. I drove this screw in next to the headblock to keep tat end in place.

 

After running a thin line of glue around the edge of the rib, I place the soundboard down on it and clamp a piece of plywood down over it  with many clamps as shown. This works well only if you've taken care to keep the edge level when sanding back the linings. 


I'm going to use a laminate trimmer to cut back the overhang of the soundboard past the ribs. To hold down the assembly while doing this, I drilled a hole in the bottom of the mold and put a long bolt through it. The wing nut holds a piece of scrap wood that is cut small enough to allow the base of the laminate trimmer to go all around it, while large enough not to fall through the soundhole. This way I can hold it firmly be the base of the mold. and my fingers won't be in the way of the trimmer.

Sign the underside of the soundboard before closing it up by attaching the back. That way, when someone uses the ukulele as a murder weapon, detectives can find your name in the wreckage of the smashed instrument and trace it back to you. Maybe that's not such a good idea after all.

Before putting the back on. the soundboard bracing must be in place. Here It's marked to be trimmed to fit. The pencil marks seen faintly on the back of the soundboard come ready marked in the kit, and  show you where to place the braces.

The bottoms of the braces were pretty rough. It's essential that they be attached to the soundboard with a near-perfect glue joint, or there will be a buzzing rattle when the instrument is played. I smoothed the bottoms by rubbing them against my sanding board.

The instructions show boards and weights being used to hold down the braces as the glue sets. I used slow (60 second) cyanoacrylate glue and clamped them through the soundhole. 

 

The bridge plate needs to be in an exact location, so that the bridge screws will engage it and so the string vibrations will be evenly communicated to the soundboard. The line marked on the underside of the soundboard should line up with  the middle of the bridge plate. 

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Copyright 2005 Stephen Miklos