Monday, November 4, 2013

drilling the wrestplank and nut pilot holes

I drilled pilot holes in the wrestplank: about 1/8", where final holes will be 3/16".  I hope that the pilot holes, done on the drill press, will suffice to guide the hand electric drill, so that I don't have to use the drill press for the final holes, once the wrestplank is glued into place and coated with finish.

I marked the holes with Sharpie, through a paper template.

I plan to use these little brass nails I found, called "escutcheon pins" (if I remember the spelling right), for the pins on the crowns of the nut and the bridges, which will form the crucial termination points of the "speaking lengths" of the strings.  The plan is to drill pilot holes in the nut and the bridge, using the drill press for nice vertical holes, and then to tap the nails in with a hammer; hopefully the fit will be just the right tightness, to not require glue and also to not split the wood.

The problem was, the nails were smaller in diameter than any of my drill bits: like with most regular sets, I can go down to 1/16".  Below that, they usually start using other measurement units for the drill diameters, and, it seems, they become a rare specialty item.  What, you people never had to drill a small hole?  All the "usual suspects" had nothing below 1/16" -- even places with Dremel tools and small hobby-type drills and such.  Fortunately, someone reminded me to check Hardwick's in the University District of Seattle.  It was a little obscure even there, but I found a set of small drill bits, and then the staff very helpfully were able to locate a tiny chuck in a different part of the store.  The drill bits are weird, they are coated with abrasives, for drilling through tile and stone, but they seem to go through wood OK without clogging up; indeed, the abrasive coating seems to let me "keep on trucking" and drill straight through even though the spiral grooves are fully clogged with wood shavings.  (They had a more-expensive set of bits that were regular steel, but I thought I'd try these first.)

The drill press has pretty poor mechanical stability, and between that and the two chucks, there was significant oscillation at the tip of the drill bit: it was not properly centered, even after much fussing and adjusting.  However, the drill bit was so flexible, relatively speaking, that it had a strong tendency to wander, which I suspect would have been a problem even with perfect centering.  The oak molding I'm using for the nut and the bridges, is quarter-round in shape, so at the line of the pins, I am drilling on a slight slope.  Wander-city for drill bits.  So, it was necessary to make pilot holes (for the pilot holes), which I did with the corner of a small screwdriver.  Once guided by the starter holes, the drill bit flexed enough to go right where I wanted it.  Still, for the many similar and more-demanding drilling tasks coming up in the construction of the action, I think I will need a smaller and more-precise drill press of some sort, for these little bits.  Perhaps just a hand-cranked drill built into the right frame.


Now that it's drilled, I can glue the nut to the wrestplank.  The whole thing will get sprayed with finish, and then I will tap in the crown pins and drill out the wrest-pin holes to their final diameters.  (I hope that the finish doesn't clog the tiny pin pilot holes so thoroughly that I can't hammer the pins into place; at worst, I might have to re-open the holes using the hand-drill: a whole lot of tedium but not the end of the world.)

The pandalon will have 49 notes, meaning 98 strings and 98 tuning pins.  The tuning pins come in sets of 100, so handily enough, there are just enough extra left over (if I don't mess some up!), so that I can build a "monochord", to test out all the aspects of my bridge and nut designs, test out whether I can get away with double stringing without tuning problems, as I believe I can, etc..  This "monochord" will have two strings (a "duochord"?), tuned in unison, just like the real instrument will have.  I'll be able to verify the actual breaking tension of the iron wire I've got, and I'll be able to hold it next to an electric guitar and get some sense for how well this wire will activate a magnetic pickup.

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