Re-imagining a 1931 Knabe Butterfly Grand – Part 3
Removing the old bridge pins. After the pins were out, I injected a mixture of hide glue and water into each hole, and then blew each hole out. The water will expand the wood, and then the glue will keep it expanded. This way, when I put the new pins in, they will be nice and tight.
After I resurfaced the bridge cap, I then burnished new graphite on, and then re-notched the bridge. This will make it slippery for the strings, and looking all shiny and new.
I then covered the bridge cap, and applied two coats of lacquer to the notches and to the cleaned sides.
Here’s the old pinblock sitting in the plate pocket. It is supposed to fit this perfectly. The curved black part of the plate that the wooden pinblock sits against is called the plate flange. This is cast into the plate and is the main thing that keeps the pinblock from shifting. If it shifts even a few millimeters, not only will the piano be un-tune-able, but you run the risk of actually damaging the pinblock or the plate.
Click on a picture (any picture on this blog in fact), to get a closer look. Just make sure you press the “BACK” button on your browser to return to this page!
This guy was lucky (sort of) The pinblock doesn’t hug the flange, (see the HUGE gaps in the closeup below), but it, and the plate survived. Of course, it still was drilled wrong, so it’s still a FAIL.
Not only does the Bass end have a HUGE gap, (very bad), but the pin block was too thick, so he just grinded a bit off!
Here’s the pinblock blank I made, sitting in the plate pocket.
Look Ma, no cavities!
After the blank is shaped, it gets a few light coats of lacquer to protect it.
Before and after – cleaning and polishing the plate screws.
Drilling the pinblock. The drill press bed is set to an angle of 6 degrees (angled away from the speaking length). This angle was calculated based on measurements taken from the plate. Also notice that there is compressed air being directed at the drill bit. It’s a very special drill, used at low speed, and the air not only keeps the bit cooler, but blows away the sawdust so that I can see what I’m doing.
After the holes have been drilled, they are very slightly counter-sunk by a special tool called a toe-hole burnisher. This tool doesn’t cut the wood, instead it compresses and shapes it, so that not only does the new tuning pin find a a guide into the hole during installation, it insures that, if, 50 years from now, the piano needs to be re-pinned, drilling out the block won’t tear the outer laminations.
This is an extreme close-up, so if you click on the picture to enlarge it, you can see the difference between the burnished tuning pin holes, and the one counter-sunk plate screw hole in the middle foreground.
The finished pinblock lying in place.
And now, in yet another little bit of re-imagining, I’ve glued and doweled the pinblock to the case. Previously, it was just attached to the plate, however, on high end pianos such as Steinway, the block is also attached to the inner rim, and the front spreader.
This will add yet another level of stability to the tuning.