Music
Glue and a few surprises
October 6. Glue. Resorcinol. Texas fudge...
Sanded everything I meant to work with today to 220 before carrying on. Will need to do it again, no doubt, but the cherry grain begins to come to life at this level. Relieved the edges on the front and back rails.
RD led me a wee bit astray, I think, with the bridge braces and gluing up the frame
10-12 ounces of glue was more (by a factor of two or so) than required to attach the dowels, the pin blocks, the backboard, and the front and rear rails.
I made two small modifications to RD's bridge braces. One aids construction of the braces themselves, the other allows more choices during assembly and easier maintenance if ever required: RD would have me drill large holes (2 inches) through the poplar braces that go directly below the brides. He wants me to drill the ones in the bass bridge braces at a 20-degree angle. This is tougher than it looks. And it is entirely avoidable: just drill two holes offset by half a diameter and then carve out the pinched in portion of the elongated hole. The Forstner bit is really good at that. I used a 1-7/8 rather than 2-inch bit.
RD's plans require that the braces be placed over the dowels before gluing the dowels in place. Fine, but I wanted to change the order of assembly to fit my schedule better. Note that if you cut out the wood below the holes through which the dowels pass, you can set the bridge braces in at any time, even long after gluing the frame.
OK, that's it for innovation today. The rest of the day was drilling and gluing and clamping.
Mixed and ready to use, Resorcinol is almost the color and exactly the consistency of brownie batter. It stains like crazy. I may have hurried the open surface prep, but I didn't know for sure how long had to work with it (2-3 hours, as it turns out). R has to set and cure at 70F or above.The basement isn't. So I brought the clamped, nascent instrument up to my office and hid it under a pile of cardboard boxes. Good thing I didn't clean up last week as I intended. It could stay there until next Wednesday, by which time the frame should have the approximate solidity of a Steinway. Amy came home and She With the Gas Chromatograph For A Nose immediately went on a hunt for "that smell." I couldn't smell anything. Which made it easy to say, "Smell? What smell?" I'll take the thing back downstairs just as soon as I possibly can.
Surprises: the backboard fit even less well than during the rehearsal clamp shown earlier. One right-side pin block hole penetrated the dowel hole and the glue erupted through it when I knocked the rails together. I think the rails are about 1/16-inch further apart than they were. I knocked and pounded and can detect no play and no room for them to move together more. It's a mystery. The backboard will probably require some bracing because that left edge is just barely in the slot at the long rail end of the left pin block. Do that at the next glue stage, or after. I will need to do some heavy sanding (or maybe worse) to get the left pin block reduced so that the left rail will fit flush with the long rail. How in the world? Don't know. But don't panic, all will be well. (Late thought: modify the inside surface of the side rail rather than the rock maple pin block -- which would you rather mess with? It will take some trial and error to sand the side rails to form, but at least it will easier than machining maple (does "molybdenum" come from the same root as "maple"?).
More surprises: paint thinner dissolves those clear plastic cups I was using as mixing vessels. (So does Resorcinol!) But forget paint thinner; R cleans up great with just water.
October 6-7. Photographed the Harvest Moon within ten minutes of Full just about 11 pm.
I unclamped and returned the dulcimer to the shop a little after midnight (it had spent 14 hours clamped at 74oF). I saw that the water used to mop up stray Resorcinol had left a rough residue or had picked up the grain on (among other surfaces) the maple pin blocks. Wanted to see if I had a trivially easy problem or something that would require research and much work. An experiment on a small area showed that just a touch with a 220 sanding pad will take the roughness right off. Whew! I'll do that soon for all the affected areas. Note that it is hard to carry a dulcimer frame through the house at 1 in the morning (i.e., quietly) when the baseboard rings like a bodhran!
October 7. Finished re-sanding the pin blocks back to 220. Rails cleaned up easily, too. All is well. Studied James Jones instrument photos to reassure myself that I can run all strings over the top of capped bridges on the sides of the soundboard. Also saw a soundhole wiith finished wood below that looks great. So maybe I'll apply a light stain under Venus and the Pleiades and go for a darker color on the soundboard. Or vice versa. Anyway, sand and prep the interior with those possibilities in mind.
Next:
- Cut out the soundboard and bridges (do it soon to allow time to find replacements if you screw it up).
- Lacquer the pin blocks.
- Insert the tuning and hitch pins (use RD's left and right mix)
- Glue the bridge supports down
- Finish the soundboard (you have plenty of test swatches, and you can cut more -- use them!).
- Make and attach side bridges.
- Make the treble and bass bridges.
- Prepare and attach the side rails.
- String it up!
- Start tuning and oiling.
Aim for a November 17 debut, but hope to have it finished much sooner in case an opportunity presents itself.
