So, now you have the body of your uke completed. It's a thing of beauty, of course, and you cannot help but admire it's smooth, even sensuous shape. So what do you do now? Why you're going to take a small router and buzz the edges of your creation with a 20, 000 rpm blade - a blade so sharp and moving so fast that one little hiccup and your uke is toast! sounds fun, huh?
I am not lying when I say that it took me two days to get up the courage to perform this desecration. I thought it through like Lance Armstrong thinks through a mountain stage of the Tour d'France. I'm talking Zen Plus.
I practiced adjusting my Dremel router base until I could take it apart and reassemble it blindfolded.
I practiced cutting ledges in blocks of wood until I could tell what percentage of a turn of the knurled adjustment knobs equaled 1/64 of an inch.
I bound and purfled the kitchen countertops....ok, that's a lie.
Anyway, you get the picture. It takes guts to cut into something that you've created, but mostly it takes preparation.
Cumpiano suggests using a hand purfling cutter to scribe the outside limits of your binding ledges and then using the router instead of a chisel to make the cut, much as I did for the rosette and backstrip. This made sense to me, so I purchased a beautiful rosewood and brass marking gauge/cutter from WoodCraft and modified it slightly for my purpose. I adjusted it for the width of the binding ledge and made a cut in a block of wood. I then made another cut for the height of the ledge on the side of the block. I adjusted my Dremel router accordingly and routed out the ledge. Pretty clean. I then tried routing without making the cuts first. Just as clean! Hmmm. I then made several practice ledges, fitting the tortoishell binding in the ledge until it fit perfectly. I decided to make my cuts with the router only. Forgive me William!
I cleared my workbench
of the usual clutter and placed blocks of cork underneath the
black of the uke to support and protect the arch. I placed a piece
of non-skid matting (the kind that is used under rugs) underneath
to hold it in place on the benchtop.
Putting on my safety glasses (the router throws a lot of sawdust and chips), I took a deep breath and began to cut. It is crucial that the base of the router lay perfectly flat on the top at all times, and that the edge guide stays at 90 degrees to the sides as it moves around the body. I went slowly, stopping every quarter to check that all was well and that the cut was even in height and depth.
The only trouble
that I had was that the depth of the ledge was reduced by half
at the headblock, where the body and neck would join. This was
due to the slight amount of dish in the top where it rested on
the block beneath, causing the router to tilt slightly inward,
reducing the depth of cut. I used a very sharp 1/4" chisel
to bring the ledge to the proper depth.
As with most of the more worrisome steps in this project, planning and practice paid off here. The very nice 5/16" carbide bit that I puchased from Stewart-McDonald along with my router base made these cuts very cleanly. Frankly, I don't think that it could have gone much better. Practice cutting and fitting on scraps of wood first, and you will be rewarded!
The next step was to cut a second ledge above and inside the binding ledge for the herringbone purfling. I was much more confident now in both my ability and in my tools and I proceded here without much fanfare. Again, I had to touch up the depth at the headblock, but all went well.
Remember not to cut either ledge
too deeply. The binding should stand proud of the sides slightly
- say 1/32" or so, and above the top by about the same amount,
give or take. The purfling should only be inlayed about half or
a little more of it's total height. The last thing that you want
to do is weaken (or, God forbid, cut through!) your soundboard.
The binding and purfling will be scraped and sanded flush with the body after the glue has dried. This takes some time, and care must be taken because of the different consistencies of the plastic and the wood used in each.
As I metioned in Step 8, bending the herringbone purfling around tight turns can be problematic. The purfling around the edge of the soundboard does not have to bend so sharply as that of the rosette, however, and it was not necessary to split it first. I did soak each strip for 1 minute in hot water ( and patting it dry) before bending it into it's channel. I used the time-tested method of holding the strips in place with masking tape until they dried and conformed to shape. The same method will be used when gluing both the purfling and the binding in place.
Routing the ledge for the binding
on the back presented a new problem: the arch and dome that I
had built into the backplate caused the router base to tip away
from the vertical, causing the bit to cut shallow in some places
and not at all in others. What I needed was a router guide that
registered more on the sides rather than the back. I contemplated
using my marking gauge/purfling cutter and chiseling out the ledge
by hand, but decided to go with another tool offered by Stewart-MacDonald
called the "Adjustable Binding Router Guide." Unlike
the "Precision Router Base"which can be used for inlay
routing as well, this attachment is really only for binding and
purfling ledges. Its tiny "footprint" where it rests
on the horizontal surface means that the arch will have little
effect on the depth of the cut.
The trade-off here is that a great deal of attention must be paid to keeping the router vertical in both axis's. I would suggest securing the uke body to the bench and guiding the router with both hands. My results were considerably less clean that with the precision router base. There was a wavy inconsistancy to my cuts that required a good deal of touch-up with chisel and file. I believe that with more practice, I could do much better.
In the continued spirit of Scottish frugality, I came up with the perfect file for smoothing the ledges: emory boards for fingernails. These can be had at the grocers for pennies apiece and have a course and fine grit on either side.
With the binding ledges
cut, it is time to prepare the endgraft. I used a wedge of tortoiseshell
plastic to compliment by tortoise bindings. I traced the piece
onto the uke body with pencil and then scribed the lines into
the wood with a straightedge and an exacto knife.
Working with the grain, I chisled out the pocket for the endgraft, matching the depth to that of my binding ledges. The depth leaves the plastic standing slightly proud of the wood, allowing me to scrape it flush to the contour of the body.
Using TiteBond, I spread glue into
the purfling ledge on the soundboard and taped the herringbone
purfling down tight with strapping tape, which is stronger and
stickier than masking tape. Even that was not strong enough to
hold the purfling into the tight bend at the waist, so I used
a cam clamp.
After an hour, I removed the tape and scraped the purfling flush with the top. Even with the clamps, there was a very slight gap at the waist. I mixed some mahogany dust, which I had collected after sanding, with TightBond to make a thick filler and spread this into the gaps with a toothpick. When dry, this filler sands like wood and is virtually invisible.
Ordinarily, most luthiers seem to glue in the purfling at the same time as the binding. This makes perfect sense if both are wood. but with wood purfling and plastic binding, one must use two different glues. I could not face having to juggle both at the same time. I used a cement for plastic binding that is available from both Stew-Mac and LMI. Like glue for plastic models, this stuff is messy and noxious. I had to forgo my pledge to use only eco-safe materials in this case, as there are no substitutes readily available. Used sparingly, it is a necessary evil. I glued the binding in place with strapping tape as with the herringbone, and because of the greater flexibility of the plastic, this time there were no gaps.
The binding and endgraft
are scraped flush all around, and will be polished when the body
is "finited" just before finishing. I will forgo the
details of binding the back as they are redundant. At this point,
the body construction is complete, and the next step is to fit
the neck. Time for a homebrew!
