Monday, June 29, 2009

Installing the Back

Monday, June 29, 2009

The facility where I work is shut down for the July 4th week and my poor wife does not get that luxury, so I get to spend a whole lot of quality time working on my mandolin.

Today I got to glue the kerf lining and the back on.

Similar to the way I aligned the soundboard when I attached it to the sides, I started by installing three alignment pins. These pins, located in the head-block, tail-block and lower point block, are actually just small nails that have been cut off and put in backward so that the point goes into the back when installed.

First I drilled the holes. The bit for this is just big enough to allow the nail to be pushed in by hand - it doesn’t need to be really tight.

Then I inserted the nail (point first) all the way to the bottom. Using my handy linesman’s pliers, I cut the nail as close to the block as I can. Because the cutters in the pliers are inset from the face closest to the wood, I know that the remaining nail will be a little long - just like I want it.

Then I pull the nail out of the hole, flip it over so that the point is up, and tap it securely to the bottom. Now, when I get the back exactly aligned with the sides, all I have to do is squeeze the two together. This will force the nail points into the back wood and give me repeatable locating holes. The nails, of course, are now permanent parts of the mandolin.

Next, just as I did for the soundboard again, I glued in my kerf lining and then once it dried, I sanded it flush with the sides.

Here is the last shot (hopefully) anyone will ever have of the inside of this soundboard.

At that point, the only thing remaining before gluing on the back is to give this sign the inside of the back so that one day, when I am dead and famous, the proud owner of #1 can prove who built it.

And now, because the internet will live forever, there is documented proof of just what it reads.

Ok. Enough of that. Back to the building thing.

As I pointed out earlier in my various attempts to use hot hide-glue, it sets-up really fast and anything that can be done to get clamps in place quickly is valuable. So in preparation for gluing the back on, I started by cleaning everything off of my workbench, dry-clamping the back to the body, and then laying out all my Bessie clamps and cello clamps so they are ready to go. Here is how it looked while I was heating the hide-glue (far left of the photo).

From start (applying the glue around the perimeter of the body) to finish (tightening the last cello clamp) took only 5 minutes. Fortunately, during my dry-clamping, I found that I could strategically apply four Bessie clamps and five cello clamps to close all the major gaps and then come back to add the remaining cello clamps. I believe I had these first nine clamps on in just over 1 minute. Here is how it looks while drying.

I’m going to let this dry over-night and then, maybe as early as tomorrow, I will use my belt sander to sand down the edges of both the soundboard and back to match the sides (both are oversized now) and get started installing binding around the body and peghead.

Sunday, June 28, 2009

Installing Fretboard Binding and Frets

Sunday, June 28, 2009.

This week was dedicated to binding the fretboard and then installing the frets. I know it doesn’t sound like much, but these two steps took an unexpectedly long time (true for a novice like me, I am sure, less I suspect once you have done it a few times).

After having completed cutting my fret slots, my next step was to bend and install the binding on the fretboard. The binding I bought is a white plastic strip that measures .060" thick x .250" wide. Being stiff and relatively brittle, the first step is to shape it to the contours of the fretboard and then glue it in place. Shaping is done with heat and the recommended glue to attach it to the ebony fretboard is weld-on cement.

During my research, I read several stories by folks who, using heat-guns to shape their binding, had overheated it and “turned it to ash”. This is good to know since I already have a heat-gun and it is the method I chose to use. Other heating methods include boiling water and hot sand or glass beads and I will probably try the boiling water method when it comes time to shape the binding for the body, but for this, I used the heat gun.

At the base of the fretboard there are several relatively sharp curves around which I needed to be quite sure that my bends were accurate, especially with respect to each other. To accomplish this, I made a small jig out of some scrap wood and drill bits.

To make this, I traced the outline of my fretboard onto the wood and then found appropriately sized drill bits that roughly matched the inside diameter of each of the bends. As you can see, I drilled the holes and then used the bits themselves as my “posts” to bend the binding around (these photos are of my first attempt at this jig where I tried to use a rod in one location rather than a drill bit - it didn’t work out so well, so I ended up making another jig). By holding the binding between the bits and then carefully applying heat, it was pretty easy to get the curves where I needed them.

Because I have a sharp corner at the base of the fretboard, I made my binding from two pieces. If you have a different contour for yours, you might want to make this from a single piece of binding. Using weld-on cement from Stew-Mac, I glued my first piece to the fretboard and held it with a combination of spring clamps and C-clamps.

Gluing turned out to be a less than perfect operation. It seems that the cement needs to be applied relatively heavy and then dries pretty quickly. I did not expect this and was not as speedy when applying my clamps as I should have. Consequently I ended up having to re-glue several places. Once I did, though, it seems to hold well.

In the second photo above, you can also see a shiny spot where the glue got on the surface of the fretboard. When this happened, I was worried that it might damage the wood or cause a stain but this turns out to not be the case. Once everything dried (24 hours) and I scraped the binding down to the thickness of the fretboard, the glue scraped right off.

Time to install the frets.

Fretwire seems to come generally in two forms - long rolls and short, straight sections. If you are a serious builder looking to make many instruments, it probably makes sense to buy your fretwire in bulk, or roll form. If you are only making one or two, like me right now, it makes sense to buy just what you need. So I bought two lengths of straight sections.

Now one of the things I read, written repeatedly by various luthiers, is that it is best to curve or arch the fret wire a little bit so that when installing it, the ends make contact before the center. This is to prevent the ends from popping out again after they are installed. Apparently this is relatively common when the wire is not arched but not so much if it is. So, wanting to do this, I looked for a way to do it. As it turns out, you can bend it by hand (the method I ended up using), cut a groove in your workbench and pull the wire through it (similar to the method you might use to curl strips of paper by pulling them down across the edge of a table), or build/buy a bending device from one of the luthier supply houses. Bending by hand, while being pretty easy, was also pretty inconsistent, but I think it worked out well enough for me.

Once I had a gentle curve in the wire, it was time to cut to length. The method I ended up using for the majority of my wires was to hold the wire against the fretboard and, using a standard set of side cutters, cut the wire as closely as possible to the edge of the fretboard. This method allows the wires to hang most of the way over the binding when installed.

Obviously, since the binding itself does not have slots cut in it, I needed to trim the “tang” on the wire at both ends. To do this, I used a grinding disk on my Dremel to cut away about 1/8” of the tang.

Then it was a simple case of hammering the frets into the slots on the fretboard. For this I used a hard plastic mallet while holding the fretboard back against the anvil section of my vice. To aid with the ends-before-center idea of the curved fretwire, I tapped in both ends first before tapping in the center. Here is what it looked like after installing the first three frets.

I don’t really like the look of the first two fret wires so I decided going to replace them but figured I better wait until all the other frets were installed before doing that.

Here it is after all the wires were installed. I do have some extra wire left so I will be replacing those first two frets.

And, finally, here is what I did toward making the fretboard extension. It is made from a scrap piece of maple and will be attached at the base of the neck under the fretboard for extra support.

As you can see from this picture, something is not quite right. I suspect that the soundboard is too thick right below where the extension makes contact so my current thought is to scrape and sand it lower and then, where needed, trim the extension to match.

With the fretboard laying on the neck and the nut (yet to be shaped) in place for spacing, it looks and feels pretty good. It even appears that the 15th fret is pretty much aligned with the break line where the neck and body meet as it should.

As I looked at this side view for the first time, I was concerned with the gap between the neck and the back of the fretboard. Having laid the two together before, I did not find the gap then, but now I do. Then it occurred to me - the difference is the frets. With them installed, there are 30 small “wedges” forcing the top surface apart and, therefore, causing it to bow. Once I have it glued on the neck and fretboard extension, this should straighten right out. It also lets me know that I don’t want to do any form of fret leveling until then, either.

Saturday, June 20, 2009

Slotting the Fretboard

Saturday, June 20, 2009.

Well, happily, it appears I lied (well, how about "was mistaken"). I was able to get a little a little bit done on the fretboard after all. Not only was I able to cut it to the ebony shape, I was also able to order, receive, and use my Stew-Mac fret saw and miter-box as well. I also learned a couple of valuable things.

The first thing I learned was that it is easier to shape the neck to the fretboard than it is to shape the fretboard to the neck. I’ll explain - the fretboard, as a whole, consists of the ebony veneer (or whatever hardwood you end up using - I am using ebony), the binding, and finally the frets. In Siminoff’s book, he has you shape the neck and then, later, go build the fretboard assembly. This is fine, assuming you are careful enough right from the beginning to not allow yourself to cut the neck too close to its finished width. I did and, as I now know, I also went to far in a couple of places.

Another way thai I now know about, is to make the fretboard assembly first (since it is flat and thin it is much easier to control its dimensions) and then use it as your template for the final shaping of the neck. Why is this easier, you might ask? Well, for me anyway, having the fretboard done first gives me a real-world limit that, for some reason, is just psychologically better than a template - I know that the fretboard is what I will ACTUALLY be using and I cannot afford to make the neck narrower than it or I have to start over. With the template, however, I'm never quite sure where exactly to stop. It might be just me, but there it is.

So for this mandolin now, I am having to make the fretboard a bit narrow to match the neck, but since it’s mine and not for anyone else, this is something I can live with. It’s a learning thing, after all.

To get the proper shape then for the fretboard, I started by cutting the ebony blank to the shape of Siminoff’s template. This gave me the correct length and shape, especially for the base. I then held the initial cutout against the neck and traced its shape onto the back of the ebony and then, because I am going to bind this with some 0.06” thick plastic binding, I offset the traced line by about 0.05”. I then re-cut the ebony to its new, narrower dimension, ready for the binding. Once the binding is installed and the assembly is attached to the neck, I should have just enough overhang to allow me to scrape the binding to match the neck without making it look too thin.

All of this I did last Saturday and, before setting out for my business trip, I also ordered my fret saw and miter box from Stewart-MacDonald. When I returned on Friday evening, there on my desk sat my new saw and miter box, just begging to get used, so today I did. This is also where I learned my other lesson for the week - cut your fret slots BEFORE you cut your fretboard to shape. Why? Because the wood is still square (or at least you should be able to make it that way) and this is really helpful when using a miter box which is, by design, cutting the slots perpendicular to its sides. Because I had already cut my fretboard sides on an angle, I now had to find a way to line it up so that my slots were cut perpendicular to the centerline of the fretboard. Here is what I did.

In the first photo, you can see I have screwed the miter box down to my workbench. Fortunately, the designer of the box builds the thing with three counter-sunk holes so it can be screwed down without interfering with the work. I then placed a wedge shaped piece of wood inside the miter box to hold the centerline of my fretboard perpendicular to the cross-cut of the saw. This is actually one of the two scrap pieces from when I originally cut out the fretboard from the ebony blank. Once I had this located so that the slots at both ends could be cut, I glued it in place with Titebond. After the glue dried, I cut a slot in it with the fret saw. This served as my locating guide and is shown in the second photo.

The next set of photos show where I lined up and made my first cut.

When I was cutting the first couple of slots, I held the wood with my left hand while working the saw with my right. I figured I didn’t want to mess with having to clamp/unclamp for each of the 30 slots and the slots aren’t very deep...This, I found, is not the best way to do it. Not only was I pulling the wood away from the guide pretty regularly but my left hand got really tired, really quickly. Enough, I said. I used clamps for the rest of the slots - much easier to clamp and unclamp than to try to manually hold the wood with a fatigued hand.

In this shot you can see where I am using some wood cauls to hold the fretboard rather than just the clamps. I initially had to do this because of the design of my workbench and where I chose to screw down the miter box rather than because of the clamps or the work itself. Toward the end as I cut the last few slots, though, it became necessary anyway in order to clamp the work securely, so close to the saw blade. I think this shows up pretty well in the picture.

And here it is after all the slots were cut.

This picture shows that some of the slots are off by a very small amount one way or the other. I credit this to the fact that I cut the fretboard to shape before cutting the slots. Had I slotted it first with a square piece of wood, I feel confident the slots would have been more accurately located and probably more square. Once again though, I think this something I can live with. If it turns out to be enough of an issue once I am finished, I can always remove it (I will be using hide-glue to attach it to the neck) and build a new one to replace it.

Friday, June 12, 2009

Filling Some Neck Gaps

Friday, June 12, 2009

Between work and some much-needed early summer-time chores, I did not get a lot done this week - but I did get a little.

After posting last Sunday, it dawned on me that I had made yet another mistake - while gluing the neck to the body, one of the things you need to do is to locate the neck at the proper depth with respect to the top of the head-block. Now this might seem pretty straight forward, but I can assure you it CAN be messed up. It’s not perfectly clear from my photos, but the head-block and top of the dovetail in the neck are in different planes - the neck plane is 6 degrees out from the top of the head-block. This means that, at best, only one edge of the two will line up while the other will be offset - no big deal provided that you align the correct edge. So which is the correct edge? The back one (closes to the tailblock - and even that is not EXACTLY the correct one) - and here is why.

The plane of the fretboard on the neck has already been established when it comes time to glue these two pieces together. The top of the head-block has not - it is flat with respect to the body. Once the glue in the dovetail joint dries the head-block needs to be sanded to match the fretboard plane. Now obviously (when your smart enough to think about it in advance) you need to align the neck so that all of the sanding is done to the head-block. I did not do this. I aligned it so that the top of the head-block was below the fretboard plane which, had I done nothing to correct it, would have meant creating a new plane for the fretboard. Not a good idea.

So what I did was to cut and add a thin shim (made from a left-over piece of maple side-wood) that matched the outline of the head-block. This, once glued to the head-block, I was able to sand it down to match the fretboard plane. Since this is located such that it is going to be almost completely hidden from view and then stained so dark that it will be almost impossible to detect, I feel pretty good about this fix.

Now, as I noted in my last post, I also needed a shim on the back of the neck. Just like the one I did on the front, I created a shim using another piece of maple side-wood and glued it to the neck. After sanding it to match the contour of the neck and the plane of the back, I think it looks pretty good, too.

I’m afraid I am not going to get to work on my mandolin next week at all (work, work, and more work), so (for all my followers) I apologize. I hope to post again in a couple of weeks.

Sunday, June 7, 2009

Neck Joint Cutting - For Real

Sunday, June 7, 2009.

Well I finally cut my neck joint - this was the step I feared the most (so far). Having never attempted a dovetail joint before, I was just new I would mess it up to the point that I would have to start all over. Fortunately, it looks like this won’t be the case - at least not for this reason, anyway.

Cutting the body side of the joint was really straight forward since the design has this cut square with the body. Since I have yet to attach the back, the rim sets nicely on my bandsaw and once the shape was transferred from the template, it was as simple to cut as you could want.

As you can see from the photos, I ended up needing to install a shim on one side of my dovetail. This is a piece of the same maple veneer I have used elsewhere and ended up being necessary once I got finished trimming and sanding the curved section of the joint on both the neck and the body. The veneer turned out to be almost exactly the right thickness right out of the box. All I did was to cut a section the right length and width, glue it on to the side of the joint and let it set up before attaching the neck.

You will also notice that there is a spacer that has been attached to the head-block. Because the fretboard will eventually extend over the body but not be attached to it, there needs to be a support onto which it will attach. Furthermore, the design has a binding strip that matches up to with the 15th fret (I will be installing that pretty soon) and yet another extension that will act as a support out over the body. This piece fills the gap between the neck joint and the 15th fret that would otherwise be there. If this is not all perfectly clear, I imagine it will be once I get that part done and some photos up. In the mean time, here are some pictures of the joint in neck.

And finally, here is the joint glued together.

In addition to the shim I talked about earlier, I added a very thin shim to the opposite side of the dovetail in the back. I installed this shim as my last step just after the joint was made up. It acted to really tighten the joint up and to add just a tiny amount of twist that I needed to square the plane of the fretboard with the body.

When you look at the back of the joint, you will probably notice that the base of the neck is set back a bit from the body. This is a result of my over zealous sanding way, way back when I was first shaping the neck. I realized pretty early that this would likely be a problem at this stage, but figured it was a small enough issue that I would go ahead with it rather than to make a another neck. Since I intend to finish this part of the mandolin quite dark and this is not a critical piece, I plan to make a maple shim to fit here.

This can be our little secret.

Now to let the glue dry and get started working on the rest of the fretboard.