This week I've had a few hours to resume work on my latest banjo - specifically, I've been able to rout out the inlay cavities on the fretboard. I've tried a couple of similar techniques for outlining the cavities. The first was to glue the computer printouts of the artwork onto the fretboard, then glue the inlays themselves on the outline. After that, I used a sharp pointed Exacto knife to scribe around the inlays. After prying the inlays off, I spread white tempera paint over the outlines, trying to rub it into the scribed lines. The water in the paint, and the water I used to clean it off, loosened the glue holding the paper prints down, leaving me (in theory) with a white outline against the dark ebony. I then started routing the inlay cavities with a 1/8" bit, followed by a small (about 1/32") dental burr for the details the 1/8" bit would reach into. It was during this phase that I discovered a bad mistake. The seventh fret inlay, a pair of sickles, was not centered properly on the fretboard. I should add here that I have not yet profiled the fretboard, just scribed lines where the edges will be. The handle of one sickle was nearly touching the line, it's opposite number was about 3/16" from the other edge line. After a few minutes of "calm reflection" over the situation, I decided that my only choices were to scrap the entire fretboard, or try to patch the area between the 6th and 7th fret slots. As I didn't have another piece of ebony to start over, and as I'd already completed the four inlays that make up the 3rd fret marker (except for the engraving), I decided to attempt the patch. First I routed the entire area out to the depth I had cut the recess so far (I'd only made the first pass), about 3/64". Luckily the fretboard blank was plenty long and I cut a 1 1/16" piece of the end, stuck it to a backer board with double stick tape, and using a hand plane, took it down a ways, and then rigged the Shopsmith in horizontal boring configuration with a sanding drum, and took a couple of passes under the drum. I pried the piece off carefully (still broke it), and fitted it into the fretboard. It was too thin on one end - I had not checked to see if the Shopsmith table was indeed parallel with the sanding drum. A couple of days later I got the time to try again. After carefully setting the table, I followed the same procedure. This time I took the patch down to a little over 1/16", leaving it proud of the fretboard surface, and glued it in. Once the glue had dried overnight, I planed, sanded, and scraped it down flush without doing too much damage to the rest of the fretboard. I recut the fret slots, then decided to take this opportunity to try a variation on the tempera technique. This time I painted the whole area with white tempera. When it dried, I used a fine pencil lead to mark the center lines, both horizontal and vertical. I went ahead and glued another printout of the artwork (with a one-piece inlay, I would have skipped this step) and glued the two inlay pieces to the printed outline. When the glue was dry enough, I scribed around the the pieces again. This time the knife left a dark outline on the white background where the wood showed through. I enhanced this a little after removing the inlays and the paper, with a scribing point. This proved to be a much more satisfactory technique, as trying to rub the white paint into the scribed lines left the lines a little to fine for the best visibility. Next up: Glue in the inlays.
2 comments
on “More inlay work - fixing a mistake”
PruchaLegend Says:
Sunday, April 5, 2009 @9:54:46 PM
Very interesting. You've certainly got more patience than I do.
banjotef Says:
Monday, April 6, 2009 @4:46:02 AM
My shopsmith is very functional and valuable for making banjos, also. I can put a sanding drum on it, and use the saw table as a small thickness sander. Great for cleaning and leveling my inlays.
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