Friday, July 3, 2009

Inlay and Routing for Binding

Friday, July 03, 2009

Well, as I said on Monday, I have been able to spend quite a bit of time on the mando this week. For starters, I unclamped the body and am really pleased with the way the back came out. Nice and tight and no apparent gaps. Although I said I was planning to use the belt sander to cut down the edges of the top and bottom to match the sides, I chose instead to use my Dremel with a sanding drum attachment instead. This worked really well and I felt a lot more comfortable that I wasn’t going to take away any more wood than need. With that done, it was time to install the point protectors.

Point protectors, if you did not already know, are hard plastic tips that are glued on to the two body points to help minimize damage. The plastic, as I ordered it, comes as a rectangular block that must be shaped to fit. Mr. Siminoff suggests shaping them first, and then gluing them on, but I decided to do it the other way around - glue first, shape in place. Here is how they looked before, during, and after shaping.

For the last couple of days have been focused on cutting out and installing the inlay work on the peghead and then preparing for the installation of the binding around the body. Because this build has taken so much time and I have come to the conclusion the value is minimal, like the ivy carving on the scroll, I have now decided not to do the ivy inlay on the fretboard. Instead, I will simply put my name on the peghead.

From what I have read, the way to go about installing inlays is to cut out the inlay material first (Mother of Pearl, or MOP), use it to trace the outline onto the wood, route out the pattern and, finally, glue it in place. So to start, I printed out a full-scale copy of my pattern and glued it directly to the MOP. Once the glue was dry it was time to start cutting.

It seems that most of the information I could freely find on the web indicates that most people use hand-held coping saws to cut out their MOP inlays, so that is what I figured I would do. To begin, though, I needed a working platform on which I could rest the part while cutting but one that would allow as much motion as possible. For this, I took a scrap piece of 3/4” plywood, cut out a slot with a hole in the center and a tongue that I could clamp in my vice. Here is what it looks like.

I have no idea what those other people use for a saw blade for cutting this stuff, but the saw blade I tried (finest I have) would hardly make a dent in it and the teeth would catch on the material every stroke. I abandoned the coping saw and moved to a cutting wheel on my Dremel. Much better (and quicker).

Now before anyone can jump on this, let me point out that I already knew that breathing MOP dust is bad for ones health so I was sure to wear a good dust mask while cutting. I also rigged up my shop-vac to suck away as much of the dust as possible.

Once I had cut away as much as I could reach with my cutting wheel, I still had some pretty major areas (and some really small, remote ones) that I couldn’t reach with anything I had on hand. I ended up making a run to the hardware store to purchase both a very fine cutting bit for the MOP and a small router bit for later when it came time to route the mating shape in the peghead. Both bits are for the Dremel.

Here I am using the fine cutting bit - also quite time consuming but well worth it.

And here I am cleaning up the finished shape with my jeweler’s files.

Once I was satisfied that the shape was ready, I located my desired position on the peghead, clamped a bottom guide in place (the blade from a small hand-plane, in this case) and traced the shape with a mechanical pencil.

Using the jig I made for cutting my dovetail as a support for the peghead, I clamped the neck to the jig and the jig in the vice in preparation for routing. I attached my Stew-Mac routing base and new bit to my Dremel, I carefully routed out as much of the shape as I could.

Even though the routing took out the vast majority of wood, there was still a fair amount it couldn’t reach. For this I reverted once again to my carving tools and jeweler’s files.

Of course as I carved and filed I would regularly check my fit against the MOP shape. What I found was that regardless of how careful I tried to be, working with the ebony wood made it really difficult to find the high spots and occasional point I had not yet notched. As a result, the cut-out ended up being quite tight in some places and much too wide in others. Here is how it looked before I glued it in.

One of the techniques that Mr. Siminoff shares in his book is that the gluing in process and gap filling process are one-in-the-same. What you do is to mix fine ebony wood dust with white glue (Titebond, in my case) until you have a very dark, almost black, mixture.

Then, using a small trowel, fill the cut-out with the glue mix and gently press the MOP into the cutout until it is fully inserted. Leave the extra glue which will shrink and suck in to where it is needed.

Once everything is dry, scrape and sand smooth.

I ended up having to add extra glue mix to fill in some gaps where I had not left enough extra the first time. Overall, though, I am quite pleased with the way it turned out.

Finally, then, I got started routing and carving the body for the binding. For this I used a router bit and binding router guide, both from Stew-Mac.

I read that this is a very delicate operation and that it was really easy to mess up, so I took extra precaution and I am glad I did. You really need to pay attention to your wood grain, router bit speed, and feed direction when doing this operation. I found that the most important thing was the feed direction. As long as I made sure to feed opposite the direction of the bit (so that I was trying to run over my chips), the tool never tried to get away from me. On the couple of times I tried it the other way, it jumped and pulled away (fortunately without causing any irreparable damage). As with the routing the peghead, there were, naturally, places I couldn’t reach with the router bit. For these, I am having to cut out by hand. That’s where I am right now.

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