Hi, Will:
I would like to add a few comments.
In step 9, you mention making go-no go gauges as in step #3. Are you sure you don't mean step #4? I don't see how a wedge (3) has anything to do with a dowel (4).
Following your steps might be easier if you have some drawings. Also, if you can name each item, it will be easier to refer to it in later steps. For example, "stretcher piece". I am assuming you are referring to the jig you just made.
How are you attaching the new block to the stretcher?
I like your ideas for jigs, as being better than measuring. I'm a member of the "Measure Once, Cut Twice" club. The fact is, even if you are perfect at measuring, the drill bits often wander and ruin your best efforts. Drilling through several items at once and using guide pins insures they will reassemble with extreme accuracy. String winders prefer a rubbing of existing wires in the piano for the same reason. If you ever have to replace a lid on an Asian import, and have to drill all the holes for hinges, lockbar, pintle, etc., using a paper template is the only way to go. One wrong drilled hole and it won't fit, and your botched holes will need filling.
Best of luck with your new system.
Paul McCloud
San Diego
----- Original Message -----
From: William Truitt
To: pianotech at ptg.org
Sent: 10/18/2009 8:47:28 AM
Subject: [pianotech] Making a fully fitted pinblock without measurements
To the List:
For some time I have been searching for the Holy Grail of locating the plate and a new pinblock to the case, without using measurements. It is my experience that anything that can be measured can (and will) be measured wrong. Or any measurement that must undergo a conversion can and will be converted wrong. So in other areas of rebuilding I have been seeking to accurately locate things with the use of indices and jigs, and not having to rely on measurements. The process I will detail is for getting the plate back exactly where it was before (which, of course, presumes that’s where it needs to be!)
But I had not quite figured out how to do this while installing a fully fitted pinblock, although I had rid myself of most of the measuring as the instrument of first resort ( and I most definitely take measurements as backup and cross reference)
Here’s what I have come up with:
Before teardown, I will want to do the following things.
1) Drill two 90 degree pilot holes in the plate at the tail, one towards the bass end, the other at the treble end. Go through the plate, through the soundboard, and an inch or so into the rim. You can do this with a floor drill press with the head spun 180 degrees and the aircraft drill bit going down the inside of the rim, or with a hand drill and bubble gauges to keep you at 90 degrees. This method we see used in most new grands and by many rebuilders. I drill a quarter inch hole and use .250 drill stock as my pilot pins.
2) Drill a hole through the plate and into the pinblock below, at each end of the plate, an inch or two from the rim sides and clearing the plate struts. This should be the diameter of a bridge pin that you will later use.
3) At the pinblock end, I use 4 pieces of carpenter’s tapered shim stock. Cut to near desired thickness, tap down between the sides of the rim or stretcher until it just snugs against the plate, then mark a line of the top of the plate. Make 4 or these, two at the ends to the stretcher and two to the sides at each end. Label them.
4) Take a 1” by 2” piece of wood scrap stock (size doesn’t matter too much), and drill a ½” hole through it on the drill press. Take a length of ½” dowel stock, goober the inside of the hole with glue, set it on top of the rim in the area of the Capo bar, tap the dowel down until it bottoms out on top of the plate at the capo. Make one for each end, and mark what it is ( I print small labels on my Labelmaker). This will serve as a quick and dirty but accurate reference for plate height later on.
5) Remove plate (this of course presumes that you have done all other protocols for teardown prior to removal of plate). Tap in an inverted bridge pin into each hole, with the pointed end of each pin sitting about 1/8” above the pinblock.
6) Cut a piece of ¼” plywood about ¼”shy of the width of the pinblock from rim to rim. It will be a rectangular piece that will be wider than the pinblock at the treble end. Rib it so that you have at least one straight edge to butt against the stretcher. Center the plywood with about 1/8” of gap at each end. Press the straight side into the stretcher, then press down against the two bridge pins to get a mark. Drill the two holes out at .125. Enlarge the holes in the old pinblock to accept .125 drill stock. Tap the drill stock into the holes in the old pinblock, and then press the stretcher piece down onto the pilot pins. You should now have your stretcher piece sitting flat on the old pinblock and butting the stretcher along its length.
7) Cut two pieces of narrow ¼” plywood stock that are longer than the width of the pinblock at each end, and narrower than the gap between the rim wall and the pilot pin. Apply glue to the bottom of the piece, and press it against the rim wall and down against the larger plywood piece. Let dry. Do same at other end. At this point, you should have a pattern which will allow you to reproduce angle of the sides of the pinblock to the stretcher. The sides of the case are often not at 90 degrees to the stretcher, particularly at the bass end.
8) Make a filler piece of ¼” plywood stock that will fit just inside the end pieces from end to end, and glue to bottom piece. This will provide a level platform for later steps.
9) Before removing pinblock, I will have made two more go – no go gauges for the pinblock as in #3 step. I will place each on top of the stretcher where it butts into the rim sides and tap the dowel onto the top of the block there.
10) Remove the pinblock from the case in your customary fashion. Use pinblock stock that will be longer, wider, and thicker than the original. Trace the pattern of the face to the flange on the new block and cut out on the bandsaw. Fit the new block to the face flange and the underside of the plate by your customary means until you are satisfied that it is well mated.
11) Clamp the new block to the plate from above and into the face flange. Center punch for screw holes and tuning pin holes. You will have enlarged the two pilot pin holes in the plate out to .125 already. Center punch those holes through the plate and drill out at 90 degrees. You can drill for plate screws or tuning pin holes now or later.
12) Having installed the .125 drill stock into the end holes, lay the pattern piece of plywood over the pins onto the new block. Trace out the shape of the pattern onto the new block. Using crosscut saw for the ends, and bandsaw and/or joiner for the stretcher, remove most but not all of the waste, leaving a little extra.
13) Place a router with a laminate trimmer bit onto the pattern and rout off the excess until the block is flush with the pattern edge. Now you have the pinblock fully fitted to the exact shape of the rim and stretcher
14) I will modify this slightly at the bass end by setting the pattern on my crosscut saw table and adjusting the angle to exactly match it, then cutting the bass end of the pinblock about ½” short. I will cut a filler block that is tapered at 1 degree, and a little fat. With the block in the case, I keep thinning it until it drops into the opening down to about ¼” from bottom. Later, when I glue the block in, the glue serves as enough of a lubricant that I can tap the filler piece down until it bottoms out on the shelf. Doing it this way allows me to remove the pinblock repeatedly and easily throughout the rebuilding process as needed, without bunging up the case sides, yet still gives me a tight fit.
15) The pinblock – stretcher Go – No Go gauges allow me to quickly ascertain whether the new block is too thick or too thin by setting it in the piano on the shelf and dropping the gauge in place. Joint or plane off the bottom of the pinblock to thin it, or add shims under the ends to elevate the block as needed.
16) If you have done everything correctly, the following should occur: With the pinblock secured to the stretcher and rim sides and glued, the plate should go back in exactly where it was before. The two pilot pins at the tail should drop through the plate and through the hole into the rim. The two pilot pins in the plate should find their hole in the pinblock exactly. The four tapered wedges should snug against the plate at their marks. The plate will be exactly where it was before, so it’s relationships to the action should effectively remain unchanged.
I do take many measurements to cross reference. I like to use a digital electronic caliper where possible as it is very accurate, no conversions are necessary, and it gives you a direct reading to record. Using it against the backside of the pilot pins, I extend the foot until it touches the rim wall or stretcher, and use a small square or block of wood to square it, to give me a consistent reading.
Any comments, criticisms, and/or additions would be appreciated and valued.
Will Truitt
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