Fretting and body work

So I finally got back to work yesterday and accomplished a bunch. The body was mostly complete, except for finishing, but I needed to trim the top and back to fit the sides exactly. In many places this was already done, but yesterday I finished this work. I started by sharpening my block plane’s blade to pretty much lethal sharpness. I then used the plane to remove most of the wood. You can’t really remove the entire overhang with the plane because at some point you’ll start removing material from the sides with the plane, too. After using the plane to do most of the bulk work I used a sanding block, made from a piece of 3/4 “ plywood, wrapped with 80-grit self-adhesive sandpaper to remove the remaining overhang. I sanded the top and back edges until they were flush and there were uniform sanding marks on the sides as well. (As recommended by the instructions I sanded very little at the neck joint to minimize distortion of the shape of the neck-to-body joint, since we want that to be tight.) Having sanded the top and back flush, I wrapped some 150-grit around the sanding block and did some cleanup on the sanding marks.


Here a problem presents itself. I fitted the neck just to check things out and it turns out that the body is a bit too thick – the fretboard rides out onto the body at the end of the neck, but the body is thicker than the neck at this joint and the fretboard will not fit. A couple of pictures will probably make this clearer.














See the “hump” at the neck-to-body joint? The fretboard will not work with that hump. I must admit that I’ve been concerned about this for a few weeks, but today I decided to just fix it. So I marked out the area that the fretboard is expected to cover on the top with a pencil, and made a mark on the edge where the neck meets the side, and went to work with a chisel thinning down the top in this area. Here you can see this work underway:


I have to assume that if I had done more sanding during the step below where I put the curvature into the top I would not have had this problem. As it is I hope that the neck angle works out (I think it will) and that thinning the top slightly in this area won’t make the top unstable (I think it won’t). Hopefully I can disguise this in the finishing, too, but that remains to be seen.

I still had some time (and energy, and guts) left after that bit of work, so I decided to tackle the start of what might be the hardest part of the project - fretting the fingerboard. The instructions tell you to do this before gluing them together, and though at first I wondered about this, I get it now. The hammering is much easier to do when you can lay the fingerboard flat on the bench rather than having to support the neck's contours sufficiently. The supplier helpfully left some extra fretslots in the cutoff piece of fingerboard for practice. I already did one months back, but as a refresher I did another. Here is a photo of the new one (I'm pointing to it):

By the way, I'd recommend buying the fretting kit from Stew-Mac - I used a cobbled together set of tools and find myself needing to order from them anyway to finish. Here are my tools, and a piece of the fretwire as delivered:

I bought the hammer from Harbor Freight and the dikes are my wife's from her stained glass kit (sorry, Babe, I'll give them back!).

Turns out that seating the frets is relatively straightforward and it only took me about half an hour. Here are the results, and a detail of a few of them (I know, I really didn't drill the fretboard dots very well!):

And here is a summary of everything today:

It's been a while, I know. I have been busy. But I got laid off about a month ago, and I don't start work again for another month. So I hope to finish the mandolin before returning to work. I got the tuners and tailpiece from Stew-Mac this week. I am out of town this weekend but will return to the project in force next week - an hour a day is my goal.

Also, found another blog just today from a much more ambitious guy than I am who is building a carved arch top mandolin. His site is very nice, and his descriptions are excellent. He's got guts - it's his first instrument, too, but his work is really wonderful. Check him out here.

Body and frets

Some progress! I was able to spend about an hour and a half in the shop yesterday and I made some progress (but took no photos, more's the pity, though I suspect that a post without photos will be well received by all three of the people who read this...).

The progress I made is principally on the top and back. Though I had already taken a block plane and trimmed the top and back as close as I dared to the sides while waiting for charcoal to be ready for some hamburgers, I still had plenty of work to do on them. I took my self-adhesive strip sandpaper, 80 grit, and stuck a length of it to the sanding stick supplied with the kit. I them busied myself sanding the top and back at their edges so that they no longer overhang the sides. This took less time than I thought it would - that 80 grit is aggressive! - but I was forced to stop when I got very close for fear of damaging the sides themselves with the abrasive. I will get myself some 120 and 240 grit self-adhesive stuff and finish the job this week.

I also bought a hammer from Harbor Freight that has a plastic head and a resin head to use in the fretting (the non-metallic heads are not hard enough to damage the fretwire). I cut myself a length of the extra fretwire provided with the kit for practice and did a quick test-fretting experiment on the extra length of fingerboard also thoughtfully provided for this purpose. It turned out to be much easier than I feared to get what appears to be a nicely installed fret. Put the wire in the groove, sharp tap at each end, and then sharp taps across the width of the fingerboard (I think three across the width after seating the ends). Of course it remains to be seen if I can do that successfully 15 times, and then get them level and smooth and properly dressed (the part that really makes me nervous, truth be told) but it was heartening nonetheless.

Body fully glued up

And here are the results of the glueups for the body. Still have to trim the top and sides, but this is well on its way.



Of course, I also still have to fret the fingerboard. And then there's all that finishing...

Top and back

Over the past two days I have glued the top and back onto the mandolin. This was much simpler than I expected (as, in fact, most of the project has been). First, though, I made some spool clamps. These are expensive - about $20 for a set of six from Stew-Mac - but simple. Basically they consist of a threaded rod with a wingnut for tightening and two short (about 3/4") lengths of dowel. To do it right you have to pad the dowel sections with cork. Since this is so straightforward, and since I happen to have a full woodshop with a chop saw and a drill press, I made my own and saved about $60. They aren't as pretty as Stew-Mac's, but they're perfectly functional, as I learned and you will learn below. Here is a shot of the spool clamps all laid out and ready for the top glueup.



I cut all of the dowel sections at once, and then cut little squares of cork and little squares of waxed paper. I drilled the dowel sections first, and then made stacks of cork and waxed paper so that when threaded onto the rod there would be a piece of waxed paper between every two pieces of cork (to keep the cork, and hence the jaws of the new clamps, from getting glued together) and drilled the stacks with the same drill press setup. I then threaded them all on one threaded rod. There was a nut and a washer at one end, and then I threaded a piece of dowel, a cork/waxed paper/cork stack, and a piece of dowel. This sequence was repeated until all pieces were on the rod, when I then put a washer at the top and threaded on another nut. I tightened the nut, and presto! the whole thing was clamped and glued.


Lesson learned - if you do this, wax the threaded rod before the glueup. The dowel sections stuck to the rod in some places and required some effort, including a heat gun in two or three cases, to get them off the rod. Oh, and the rod was toocaked with hardened glue to use for making the clamps themselves as well.

These pairs of dowel were then threaded onto 6" pieces of threaded rod with a hex nut at one end (the fixed end) and a wingnut at the other end (the moveable end) with big fender washers under both nuts.

These clamps are invaluable for gluing on the top and back. With the cork lining you don't even need cauls.

I then glued on the top. Here are some photos:











And here are the results:













I did the back today. Photos:

Fitting the top

So I finally got to work a bit on the mandolin this weekend again.

Today I glued the back brace onto the back, cut notches in the kerfing for the top braces to fit into, and trimmed the top braces so that they fit into the notches behind the sides.
First I glued the back brace on. Since I already wrote ad nauseum regarding gluing braces when I wrote about the top, I will refrain from kills virtual trees here repeating that information. I'll just show a picture of the back and back brace glued up. Next step for these pieces is carving the brace.

The next step is to fit the top to the sides. To do this you start out by cutting notches in the kerfing so that the top braces, which in some cases extend almost all the way to the sides, can fit. We start out by lightly clamping the top to the sides, making sure that the centerlines align, and also making sure that we are clamping to the top (as noted in a previous entry the hole for mounting the neck is offset towards the back so we have to make sure we clamp the top onto the correct side...). Then we make marks on the sides where the braces protrude, and then transfer those marks to the kerfing, which we are then going to notch out. Per the instructions I used my handy Xacto knife to cut the notches. Here are some photos of the process.

Finally you have to trim the braces so that they are short enough to fit. I used my trusty Marples pull saw and a chisel. Here are photos of that:

And here is the top, "snapped" into place with the braces in their notches.

Carving braces, or something to whine about!

Well, I finally found something to complain about in the mandolin kit. I’ll say again that I really feel that the kit itself is fantastic – the materials are great and everything is well thought out. I couldn’t be happier with them.

Recently, though, I have begun the process of gluing on and shaping the braces for the instrument. The instructions are somewhat incomplete in this regard. As I noted elsewhere, the instructions don’t really have any kind of direction on when to shape the ends of the braces during the glue-up process. It turns out to be practically unambiguous because you have to shape the ends of the short braces on the top before notching and gluing on the trans braces on the top. If you look carefully at the photos for the surrounding steps you can even see it has been done in the photos (although the photos for the nothing and gluing of the trans braces show the short braces carved in one photo and not yet carved in another, so that you can’t even get useful information indirectly on this point). But the instructions don’t tell you to do it at this time, and crucially they don’t tell you how to do it, either. You get some instruction on this point in a later step (there are two places where you have to shape braces), including a photo (the photo I included with my last post), but this is a logic bust in an otherwise very well constructed set of instructions and drawings.

What I really found disappointing is that I can’t find any instructions anywhere in the plans on when, or again crucially, how, to carve the braces. To make this deficiency clear it will pay for us to look at a photo of the plans.


This is the plan cross section of the short braces. See how the braces are supposed to be carved in a sort of boat hull shape rather than left rectangular in section the way they are delivered? (For my purposes I will use the word shape when talking about shaping the ends of the braces and the word carve for carving the sectional shape into the braces.) The plans don’t tell you when to do this carving. Now, it might seem that it doesn’t much matter when you do it, as long as it gets done before you glue on the top. It might even seem not to matter if you do it, although clearly not carving the braces has the effect of leaving an inelegant feature of the instrument and more critically of negatively affecting the response of the instrument while playing. (I read this in Guitarmaking, the Bible on the subject. I don’t know this from experience, but as a structural engineer – at least by training – it is obvious that this would be the case. Leaving the braces uncarved would substantially increase the stiffness of the top, thereby reducing its response to the vibration of the strings. Usually considered a good thing in highway bridges, but it would be a bad thing in a mandolin.)

Back to topic, the problem is that there is definitely an optimum time to carve the braces into this shape. You can’t carve them before gluing them to the top because then you’d be trying to clamp a pointy surface and the clamp would have trouble gripping the brace, and the extra material makes the brace stiffer so that you get more uniform clamping pressure with the limited number of clamps that can be brought to the party. So carving them on a bench away from the top is out. You therefore have to glue them on and then carve them. But that’s where it gets hazy for me. What do professionals do about carving the braces?

Let me take a moment to explain that carving the braces is tough. You can see in my photo that this was the hardest part of the process for me so far, and in fact I didn’t do it all that well. I’m satisfied enough to glue the instrument together – after all, except for the readers of this blog nobody but me will ever see the braces once they are inside the instrument – but obviously a professional builder would probably resort to using the top as firewood rather than sell the instrument with these braces on it. I suspect that the professionals use little planes in this process to take very thin, regular shavings of material, for at least part of the time they are carving braces. I don’t have any way of knowing this, though, because the plans did not include a single word of instruction on how to carve the braces. In fact, other than the little section on the plans and the fact that some of the photos – but not nearly all of them – show the braces carved into the desired final shape, carving the braces is simply omitted from the instructions entirely. So I used a chisel to carve them – the same one I used to shape the ends – and it came out better on some of the braces than it did on others. I think the short top braces look OK, but the trans braces look much less so. If you were to look carefully at the top of my instrument you would also see several places where I gouged the top ever so slightly while carving the braces. Unfortunately the cardboard mask I was using to protect the top while shaping the braces was too thick to permit its use during the entire carving procedure. I sanded these areas smooth.


Again back to our topic – when and how to carve the braces. I addressed the difficulties in carving the braces above, and also the method I use as well as the method I suspect the pros use. But the timing thing is another problem. You see, I glued on all four top braces before carving any of them. I’m betting that a professional would have glued on the two short braces, shaped and carved them, and then glued on the two trans braces. That way you would minimize the interference of other braces when carving the one you are working on. Sadly this did not occur to me until I was essentially locked (glued, you might say) into doing it my way. Because of this a small plane of the type I hypothesized about might not have been much help to me – the other braces would have interfered with the sole of the plane and prevented long cuts to the ends of the braces. Maybe pros don’t use planes for this very reason. At any rate, I carved the two short braces after taking the long braces out of the clamps, and then shaped and carved the trans braces. I wish I had done a better job but I guess you have to do it a number of times before you’re going to be great at it. The job I did will suffice for my first instrument, and I’m sure I will do things a bit differently on the next one.

Here’s a photo after the carving and shaping step (the other short brace looks much like this, the trans braces don't look as good):


Memo to Stewart MacDonald: please add some clarification of the carving process, and please do it in the appropriate place in the process. And thanks for the otherwise great kit!