This is going to be a Steinway D soundboard for Manhattan School of Music. Our Masonite pattern was destroyed in the building fire and firefighter's effort putting off the fire with massive amount of water. Here we have a pattern made of tarp. At least it is water proof. There are several lines marked 45° from the belly. Lay raw wood stock following these lines. Leave each piece of wood at least 2 inches (5mm) longer outside of the pattern edge. If the lumber is too long, trim it shorter on a chop saw. The soundboard will be 10mm after sanding. The plan is to mill the wood to 11.5mm before gluing. So the lumbers selected are at least 12.5mm thick. The first and last pieces of wood should cover just the edge of the pattern giving it about 8" (20 cm) room on each end. The wood width will be reduced through milling. On the first or last board, write down the piano make, model, and customer's name. Write down the order on the two ends of each board. Write the numbers narrowly on the center line since the wood thickness will be reduced and part of the number may be lost. Note that at the beginning, we have 14 boards for this Steinway D. The boards are now brought to the machine room to be milled. Use a crayon or chalk, draw waves on both sides of the lumber covering the whole surface. This way if a spot is low, the waved lines can be seen. The boards are finally milled to 11.39mm, close enough to the planned 11.5mm. Observe any defects on the wood. They need to be milled off. Flatten one edge on a jointer. Check that the jointer fence is 90° to the table. The flattened edge is usually the opposite side of defects to be removed. On a table saw, ride the flat edge on the fence, rip off the unwanted part on the other side. Sometimes a long board has knots in the center, has to be chopped into two pieces to be used as almost-flawless stock. Ideally, mill the wood in the period of several days, mill one side, wait until it settles, then mill the other side a day later. The aim is to have the wood flat and stable, not to warp again. Bring all lumbers back to the fitting area, check if the layout is still larger than the pattern, giving about 6" (15cm) extra wood on the first and last board. Re-mark the board order on two ends of each piece. Make sure if any board cups, the cup faces downward to go with soundboard crown. The tongue and groove routing station is connected with an air compressor. The metal top/fence comes down to clamp the wood being routed. The depth jig with adjusting screws lets the board edge stay 2-3/8" from the fence, match the router base. The router base will ride along the fence. Hold the wood against the two screws, push the depth jig to the fence, then press the air control on the floor to clamp down the wood. If the wood is too short to touch the two screws on the depth jig, measure 2-3/8" from the fence to the edge of wood at both ends, hold it, and press down the air control. Check that the wood is clamped firmly. There could be a piece of supporting wood on each end of the soundboard stock for the router base to sit on. For a good solid clamping, make sure the two supporting pieces are lower than the soundboard stock. Rout all tongues then all grooves, or the other way around. This way, it is hard to get confused or disoriented. The groove router bit set includes one smaller bit, a larger bit in the middle, then a smaller bit, all sandwiched together. Color the routing surface with a chalk or crayon to later observe any uneven routing results. Set the router down on one end, blade not touching the wood, turn the trigger on, ride the router base against the fence and rout across the board. Walk evenly and steadily for this. Open up the groove wider with the edge of a sanding block. The tongue router bit set includes one larger bit, a smaller bit in the middle, then a larger bit, all sandwiched together. Coloring the routing surface is not needed. As long as there is a tongue to go into the groove, it is good. After routing, sand the top edge, bottom edge, and front side of the tongue to remove splinters. Put all the wood together in order, tongue in groove. Check if there is any uneven joints. Re-rout when necessary. When all joints fit well, check if the whole set is still slightly larger than the soundboard pattern. Add wood when needed. Layout the clamps. We have 4 sets of Wood River 4-Way Pressure Clamping System. The regular bar clamps are in between. With a pencil, mark the location of the pressure clamps. Place the clamps aside in their order. Measure the length of the marks, pick the spacer at the matching length. The taped spacers make sure that the woods are properly pressed together. The glue won't stick on the tape, which makes the unclamping process easier. If extension is needed for the soundboard stocks to fit the pressure clamp, include the length of the extension for spacer selection. On the groove side, mark where the tongue ends. No glue will be applied beyond this mark so the clamp ends can be kept clean, free of glue. Set the bottom part of the pressure clamps in place, tape on the spacers. The clamps are better raised with platforms for easy clamping later. Clamp the first piece of the soundboard on its pressure clamp, the pencil mark of the clamp on the top surface of the wood should be just above the bottom clamp. Piece all wood together to dry fit. Adjust the location of the pressure clamps so they are just under the pencil lines. Apply glue between the marks where the tongues end, spread evenly with a brush. Piece by piece, glue the soundboard together, the clamp lines should line up. Place the spacers, then the top pressure clamps. For soundboard extension between the pressure clamps, a small spacer underneath maybe needed so the extension piece stay flat. Sometimes a couple small pieces of spacer are also needed between the clamp ends and the edge of the soundboard. Play by each situation. Apply the bar clamps with wax paper underneath. In the end, all clamps must be tightened to the same amount of pressure. The glue squeeze-out should be even. For a easier sanding process later, clean up the glue squeeze-out as best as can be. Here Joe placed all bar clamps under the soundboard. It looks much neater and no wax paper is needed between the wood and the clamp. Leave the glue to dry over night.
Comments are closed.
|
Archives
January 2025
|