Monday, August 23, 2010

Fixing Mistakes

A lot of lutherie is learning how to fix things when they don't go as planned.  And it's not uncommon for things not to go as planned.  It's so not uncommon, that there's a particular thrill when something actually goes right.

So last week it was time to rout the rabbets for the bindings on the guitar, so I got all the stuff out to do it, including the bearings that go on the router bit that control the depth of the rout.  I found the correct bearing, installed it, did some tests cuts on scrap, and then it was time.

It's actually kinda scary to start cutting into the guitar bodies, so I'm always nervous when I actually move from scrap pieces to the actual guitar.  I started with the back of Quigley's guitar and started routing from the middle of the lower bout to the butt, and then back toward the waist.  As I approached the waist, there was a funny noise, something went flying, and the guitar kind of jerked.  I turned off the router and looked at  the body.

There was a nice little gouge in the back deeper into the body than it should have been.  With a sick feeling I looked at the router to see what might have caused it.

Seems that I hadn't tightened the screw holding the bearing to the bit enough, and over the course of cutting the test pieces it had been working loose, and finally fell off.

Well, the screw fell off; the bearing went flying.  Without the bearing, the bit cut deeper into the body than it should.

Here's what it looked like:

Well, that's enough to ruin your day!  So, now what do I do?

My first inclination, right in the middle of my frustration, was to cut the back off, toss it, and start over again with a new back.

Deep breath, dude.

Next I looked to see if I could widen the rabbet all around and add more purfling than the simple black/white/black purfling I had intended.  Thing is, to cover it I would have needed the original b/w/b purfling, then something wider like a herringbone, and then another b/w/b purfling.  Backs don't normally get that much ornamentation, I don't think it would have looked good anyway, and I would have had to decide whether to match it by doing the same thing on the top.

In these situations it's always good to take some time.  So I turned everything off, went inside, and watched TV for the rest of the day.  Ate a whole bag of potato chips.  Not really, but I felt like it.

By the next day I had decided that I could recover from this.  So here's what I did.

I got the part of Quig's back that was leftover after I cut the shape out--called the offcut.  I used a contour gauge to duplicate the shape of the gouge.

I transferred that onto the off-cut where the grain lines matched the area of the back, and cut it out on the bandsaw. Then I did a lot of filing of both the patch and also the gouge to give it a more regular shape.  I got it to fit as close as I could and then used Tite-Bond to glue it up.  After a couple of hours I sanded it flush.

And here's what it looks like now:

Pretty nice, huh?  From another angle you have a hard time finding it.  With the binding installed it won't be noticed unless you know what you are looking for and where to look for it.

Yesterday I went back to routing the rabbets, and had no more incidences on either guitar.  I'll finish tonight and start gluing the binding and purflings.

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