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by David Vanderhoofven, RPT (030604 MMDigest)
Greetings! Rod Sprattling wrote about needing to make a new bottom board for an upright piano that had water damage.
I was called upon to repair an old upright piano that had a large crack in the bottom board (the board to which the pedals and trapwork are attached). The bottom board was badly damaged, and needed to be replaced.
I thought it would be useful to have a step-by-step list of procedures to follow when I need to do this repair. This information may be useful to you as well.
Attached is a repost of a message that I originally sent to the PTG email list called Pianotech on October 16, 2001. I hope that this information is helpful to you.
Making a New Bottom Board for an Upright Piano
The purpose of this procedure is to make a new bottom board for an upright piano when necessary. The pedals of the piano are attached to the bottom board, and if this board is cracked, broken or otherwise damaged, the pedals may not function properly. Also, if this board is damaged (cracked, stripped out screws, etc.), the pedals may make unwanted excessive noise or squeaks. This is intended to be a step-by-step explanation of the process I used when I recently made a new bottom board for an upright piano.
Tools and Supplies Needed:
* Table saw or Skil-Saw
The shop should be well lighted, have enough space so that the technician can move around comfortably, and must have good ventilation. There must be no open flames or other sources of a spark that might cause the lacquer used to burn or explode. A spray booth or other draft free spraying area is useful.
1. Remove lower front panel, and disengage and remove pedal rods
2. Lay piano on back using piano tilter
3. Remove screws holding bottom board in place
4. Remove bottom board
5. Measure dimensions of bottom board (thickness, length, width)
6. Cut new wood to dimensions of old board using table saw or Skil-Saw. If the old board is wider than the wood you have available, it may be necessary to glue up several pieces of wood to get the necessary width. If this is the case, the following steps apply.
A. Use jointer to get smooth edges on wood
B. Use biscuit jointer to cut slots for biscuits (or use electric drill and dowelling jigs to drill holes for dowels)
C. Apply wood glue to both edges of the wood you are gluing together. Apply glue to slots and biscuits (or apply glue to dowel holes and dowels)
D. Insert biscuits (or dowels) and clamp edges of boards together.
E. Wipe off excess glue before it dries
F. Allow sufficient period of time for glue to cure (24 hours)
G. Use cabinet scraper or chisel to scrape off excess glue. (Of course, if you use plywood, steps A through G can be omitted.)
H. Cut new board to dimensions of old board
I. Sand surface of wood smooth
7. Use router and router bit on new board to duplicate edge profile of old board
8. Spray underside of board with several coats of flat black lacquer, and spray upper side of board with several coats of clear gloss lacquer. Allow sufficient time for lacquer to dry.
9. Repair stripped screw holes in underside of piano - epoxy pinblock plugs in place.
10. Replace bushing cloth around each opening in kick board. Replace any worn bushings in pedal assembly. Polish pedals and clear coat with brass lacquer if desired. Polish and lubricate pedal pins (replace pedal pins if necessary).
11. Position new board in place on underside of piano and clamp in place. Drill pilot holes for screws to hold board in place. Drill through new board into bottom of piano using drill bits of correct diameter, and drill to appropriate depth (use depth stop if necessary. Use a countersink bit so that screws will be flush with the wood surface. Install several wood screws to hold bottom board in place.
12. Locate pedals in correct place and mark screw holes through the pedal bracket holes. When in proper position, the pedals should not rub on kickboard on either side, and the pedal horn should not rub on wood of kickboard.
13. Remove bottom board and put on workbench. Drill holes for pedal brackets, and install pedals and brackets.
14. Install bottom board, making sure to tighten all screws securely
15. Using piano tilter, return piano to vertical position
16. locate proper position for trapwork springs, mark and drill holes, install trapwork and springs with wood screws
17. Install pedal dowels and regulate pedals. Check for squeaks
18. Reinstall lower front panel
Of course, if you have the piano tilted on it's back, this is an ideal time to take care of any problems with the casters.
Thanks to Kevin Way, South West Missouri Player Piano Service, for excellent help and advice and the use of his jointer and clamps.
David A. Vanderhoofven, RPT
05 June 2003
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