Friday, January 30, 2015

Day 67: Getting Ready for the Sharp Tops

I purchased some Titebond Hide Glue today. Whether it's as good as traditional hide (yes, made from the hides of animals) chips melted in a glue pot remains to be seen. All reviews I was able to find on the Interwebs were favorable and this is one of the questions I will be asking Owen Daly when I visit his shop in February.

The reason I'm switching to hide glue for the key tops is that once the glue is dry, I can heat it and it will soften up enough to remove a top without going all drama queen and slicing it off using Little Buddy (my 12" band saw). The glue will also adhere to itself. By this, I mean that, should I separate a top from a key, I would not need to sand the surfaces completely clean to reglue them as I would with, say, Titebond II yellow wood glue. Wet hide glue sticks to dry hide glue without the extra cleaning step, though I would sand things up a bit to get a good fit.

Hide glue is used pretty extensively by violin/viola/cello luthiers and others such as harpsichord builders who occasionally have the need to take instruments apart for maintenance purposes. I wish I had used this glue on all of the keys. I was able to get the natural key tops measured, cut and glued for keys 20 and 51 using it, which is a good experiment to see how it holds up after drying. Hopefully, I won't need to remove either of them in the near future.

Once I clamped up 20 and 51, I was free to move on to cutting the key top laminates for the sharps. As you may recall, this instrument is in the Arts & Crafts/Craftsman style, so I'm using quarter sawn red oak for the case, legs, bench, and sharp key tops and African blackwood for the naturals and other accents. I recently purchased a nice Thin Rip Table Saw Jig from Rockler Woodworking and Hardware that allows me to cut at 1/16" and 1/8" inch intervals with ease, and it's astonishingly accurate.

Using this new jig with a featherboard allows me to cut the sharp key tops at 1/16" (2mm) with incredible accuracy and safety. Mr. Miller states in his eBook Most Excellent that the sharp tops need to be exact clones because the human eye is able to detect minute differences in them very quickly. In this case, the first step is cutting them at the right height, which I've been able to do here.

Before I could start ripping the tops, I needed to extend the blade slot of my zero clearance table saw throat plate. This type of plate comes with no blade slot, which means you must install it, start the saw, and then slowly and carefully raise the blade to cut through the plate. The result is a clean cut with little to no clearance between the blade and the plate, This is done to prevent thin cuts from falling back into the blade, something that is not only terribly frightening, it's really, really dangerous.

The trouble with the current zero clearance plate was that I had added a riving knife to the saw during the recent Tortuga Early Instruments Holiday Maintenance Program. Because I had cut the plate before that installation, there simply wasn't room to raise the blade and, hence, use this particular plate for safety. Thus, I decided to extend the cut using my trusty scroll saw.

I noticed once I finished that I had set the blade to move so fast (a scroll saw is like a sewing machine with a jigsaw blade, rather than a needle) it melted the plastic and closed up the cut as fast as it made it. Yes, sometimes I worry about me. Upon closer inspection, I saw that the cut was still there, it just needed some of the melted goo to be cleaned out, so I grabbed a fine-toothed hand saw and cleared the path. Once installed back on the table saw, it worked beautifully.

Tomorrow, I will size and shape the sharp key tops in preparation for gluing them to the keys using - you guessed it - hide glue!

Until then...

No comments:

Post a Comment