Sorry for the delay in this post. I've been distracted by various things (the bass included!), and on the road with the band. I started compiling my pictures and notes yesterday and now it's time for an update!
Last week I got to James shop in Asheville, NC and I proceded to have my mind blown. He started by inspecting the whole bass and assessing what needed to be done. There was a few issues with back delamination that he addressed, but the focus of this session was the top, so that is where I focused my pictures and where I'm focusing this post.
The first issue to address was the sagging belly under the bridge feet. James is a strong proponent of using heat pads to bend wood. The pads are made by Watlow, and require a 120V AC power supply with a rheostat to adjust the temperature.
He used a caul made of thick mahogany (although just about any thick & rigid piece of wood will work), hollowed concave to conform to the top.
The top is placed against the caul face-down (with a protective cloth, of course), and a heating pad against the back-side of the top. A thin piece of plywood is placed against the heat pad for a clamping surface, then the top/heatpad/caul sandwich is clamped using several cam-clamps. I can't say the exact temperature he used, but I know we left it clamped for at least an hour.
The next step was to make the belly patch. James likes to use well dried red spruce, about 1/8" to 3/16" thick (James if you read this, please correct me if I'm wrong). The patch is an elongated half circle (see picture) starting lengthwise from about an inch below the top of the f-hole, extending 3 to 4 inches below the f-hole, and the width from the edge of the bass bar to within a half inch of the f-hole. Once the patch is applied, the edges are feathered out an inch or so from the edge.
Since we had a limited time-frame, James glued and clamped the belly patch, the delaminated layer under the bass bar, and the bass bar all at the same time. In order to glue so much at the same time, James used another heat pad to pre-heat the areas we were going to glue. This allows for more time to clamp before the glue sets. He kept telling me that under normal conditions, he would do these jobs separately, mostly so as there's plenty of room to clamp. As you can see there is not a lot of room for more clamps!
The next day we removed the clamps, and applied fabric to the ends of the bass bar. Drench the fabric in glue, as it will absorb a lot. This strenthens the bond of the bass bar with the top ten-fold, so you will never worry about the bass bar detaching again.
This is where my time with James came to an end. What a valuable experience this was! For those who have had the pleasure of meeting James, you understand when I say he is an exceptional human being - in so many ways. I am humbly grateful for this experience and the work we (99.9% HE) accomplished, which he gave me an awesome deal on BTW. I can't recommend him any higher for any of your upright bass needs.
Now, onto the rest of the work. I will post another update later when I get a new bridge and do the remaining setup work. It may be some time as I have some gigs and travelling to do. Until then, happy bass-repairing!