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:

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.

Recent work

Well, I've had a bit of a hiatus while I took care of some personal business in the past few weeks, mostly related to a small but significant bit of elective surgery I had over the past weekend. For the record it was not plastic surgery of any kind...

At any rate, over the several weeks since my last post I have accomplished a bit but not had time to post about it. Actually, I also failed to take photos of most of these steps, but fortunately they aren't really visually gripping steps to miss.

What I did over the past few weeks was exactly what I said my next steps would be in the last post. I glued the short braces onto the top and sanded the kerfing to match the radius of curvature of the top. Fortunately the kit builder again thoughtfully configured the sanding stick setup so that the sanding stick, with the additional pad attached, resulted in a radius of the correct curvature. Basically you attach a strip of self-adhesive 80-grit sandpaper to the end of the sanding stick (7" in from the end, actually) and then, keeping the additional pad on the side of the instrument directly across from the area being sanded, you just sand the edges until you have properly contoured and leveled the kerfing. To aid in doing that you scribble with a pencil all over the kerfing. When the pencil lines vanish you have done your job. The key here is to keep moving around the circumference of the edge to ensure that you remove material somewhat evenly.

Here's a photo of the sanding stick setup. See the strip of sandpaper attached to the stick, and the additional pad? This photo was taken after some sanding of the top edge of the sides.



I also glued on the short braces for the top. I can't do any additional gluing of top braces, or really of the bottom brace either, until I get a set of more or less lutherie-dedicated cam clamps, so I'm somewhat stymied at this point. I failed to take a picture of the top with both braces glued-up, but rest assured that the process was identical for both braces and that the top pretty much looks just like this, but with two braces attached. Here is a photo of the brace being glued from the "inside".


And here is a photo of that same gluing operation from the outside, showing a piece cutoff from the top being used as a caul to protect the top. Note that cauls were not used on the braces since they have to be carved and will lose much of the material in the area that the clamp would have been bearing on anyway.


And, finally, here is a photo of the top with one of the two short braces attached.


I also spent some time tuning a bench plane which will be crucial to the shaping of the braces and neck and to the trimming of the top and back to the sides. I never really understood that almost all planes, and other woodworking cutting tools like chisels, require substantial preparation in the shop before they can be used, even if they are purchased brand new. While some of the very high-end planes might come with flat soles and very sharp irons, most do not. On a bench plane you can also spend a considerable amount of time ensuring that the bottom is a true 90 degrees from the side of the plane. Fortunately in my case the sole was very flat when the plane arrived, and the sides were close enough to 90 degrees from the sole to be acceptable for my purposes. I am somewhat surprised by this since because this is just a bench plane and not a high-end plane like a smoothing or jointing plane I bought a Stanley and not a really good plane. But a few minutes of (frankly) significant exertion really got this plane into usable shape. Mostly it was just flattening the sole by polishing it on 80-grit sandpaper adhered to a piece of polished granite I got through my previous employer that is truly flat and very, very stable. I then polished it with ever increasing grits until the sole was flat and mirrorlike. I have yet to sharpen the iron in exactly the same way before being completely pleased with the tool, but it still makes impressive shavings despite the relatively cheap nature of the tool. But this is a bench plane, after all - how accurate are we really expecting it to be?

At some point I will post some details about my sharpening system. Basically it is the Scary Sharp system (link, perhaps not to the originator of the system using that name, to the right), using a Veritas honing guide and several pieces of polished granite with various grits of sandpaper stuck to them. My good friend Joe Barker, who is building a sailboat in a room about 5% larger than the boat and blogs at http://barkerboat.blogspot.com/, uses the same system (I gave him several pieces of the granite, too) and he has more details at his site. Ignore all the Old Style comments over there. He has great taste in beer (and women) - he just wants to feel like a boat builder and you just can't get Narragansett beer in Cincinnati.

Biggest day yet, part II

Blogger kept crashing on me near the end of the last post, so I elected to split them into two posts. If you haven't yet read about shaping the braces, read the next post before this one.

Here you can see the top and back, along with the cutoffs (which the plan suggests keeping for use as cauls later in the project). On the right are the three major components to date – the top, the sides and kerfing, and the back.

And here's an exciting photo – I stacked the parts together on the benchtop just for giggles and took a photo. At some point in the near future the instrument will be glued together like this and then the top and back will be trimmed to final shape. I just thought it would be cool to see it like this.

Since I still had several hours (at this point I had spent only about 1.5 of my 6 or so) I decided to cut out the soundhole as well. Now, the plans suggest cutting the soundhole patch using a hobby knife. I had been dreading this step because I was frankly worried that I would cut this poorly and damage the top by over cutting. It had to get done sometime, though – so here it goes.

The photo on the left shows the soundhole from the kit manufacturer with the soundhole patch glued over it. The photo on the right shows the results of the rough-in cut out (as suggested by the plans I made a first cut a bit shy of the edges of the soundhole, followed by a final cutout to actual shape). As you can see in the left photo below, I did some minor damage to the top wood surrounding the soundhole when cutting it out just as I had worried. However, the next step in the plan is to smooth and bevel the edges of the soundhole with sandpaper so I decided not to worry too much about minor damage. Fortunately the damage turned out to be very minor indeed – the photo on the right is the soundhole after smoothing and rounding with some 120 grit sandpaper (the MDF of my benchtop is also visible here, and it might make the soundhole hard to make out. Sorry.)

These last two photos are of the top after all the work of today was complete. The one on the left is of the inside of the top (the side that will not be visible after the instrument is complete). You can see the soundhole patch and the markings for all the braces in this photo. The one on the right is of the outside of the instrument.

Next time I will be sanding the kerfing to match the curvature of the top and back, and gluing in some of the braces. Not too long until the body is largely complete!

Biggest day yet

Wow! I got several hours to work in the shop today and the outcome was better than I could have imagined. My wife took the kids and went off the visit her parents, and she instructed me (this is why I know she's the right girl) to work on the mandolin. I got more accomplished today than any other day of work on it yet!

I started off by shaping the braces for the top and back. The kit includes a specially sized “sanding stick” made of ¼” plywood. They even included a little piece of the same plywood for use as a caul for clamping the stick to the benchtop. The kit designers thought this step out well, and planned for it well, too – the caul that was included for the outside of the sides at the neck block it just the right height at the edges to result in the proper radius of curvature when used to elevate the non-clamped part of the stick. The following pictures should give some idea of what the heck I'm talking about:

The photo on the left shows the stick clamped to the benchtop and propped up at the other end using the neck block caul. A clamp holds the neck block caul in place – I found that the two clamps at the bench kept the stick from rotating sufficiently. As directed by the instructions I also supported the stick at two other points along its length; one of the supports is the tail block caul and the other is a piece of scrap left over from the toolbox I built for my son for his birthday. The picture on the right shows the same setup from above just for clarity. You can see the self-adhesive sandpaper (80-grit as recommended) in the photos.

The instructions say to sand one of the braces and compare it to the drawings, adjusting the curve by moving the neck block caul in or out until the curvature is satisfactory. You then sand all of the braces using that same setup so that they are the same. I found that, by luck, my setup worked out very well the first time, so I went about sanding all of the braces to the curvature shown on the plans (which the instructions helpfully tell me is about an 8' radius).

The picture on the left is an action shot of me sanding one of the braces. I used a longitudinal motion to sand them – that is along the length of the stick and not side to side across it. This just seemed easier and the results were good, so I guess it's OK – at any rate it matched the grain direction so it made for clean sanding. The photo on the right shows the completed braces. Note that there are two #3 braces.

The next step is rough-cutting the back and top. I had not originally planned to do this today, but the shaping of the braces went so well and so quickly that I decided to have at it. The instructions say to cut the top and back with a bandsaw if you have one. Since I do I decided to give this a shot.

Up until today I had not had luck with my bandsaw, which I bought used (along with almost all of the rest of my stationary power tools) from a guy who was liquidating his shop. I examined the saw and realized that I had not been setting the damned thing up correctly. Not one of the cuts I had tried with it had been successful until today. Today I adjusted the tensioner more carefully and realized that I had not been properly adjusting the blade guide. After having done this the saw cut like a dream. Lesson learned – adjust your bandsaw carefully for each situation and it will cut much, much better.

I used the bandsaw to cut out the back and sides (the instructions tell you to leave about ¼” proud for later trimming to the actual shape of the instrument). Because I was not being very careful about accuracy since I was leaving the cut proud it went fast. I first had to mark the brace on the back and trace the outline (the left photo) and then cut it out on the bandsaw (the right photo).

Flush with my success I then cut out the top as well.

Kerfing for back

On Monday I took the mandolin out of the clamps (err... clothespins) and examined my work. Here is the result of the glue-up of the kerfing for the top of the mandolin:


Here I'll take a moment to once again try to explain kerfing. I now have a couple of good examples of what it looks like in the field.




See how the kerfs in the wood (the word kerf refers to the bit of wood removed by the passing of a saw blade, so here they are the notches in the wood) allow the wood to bend smoothly while still maintaining a nice bit of glue surface on top?




Here we have two closeup details of what the kerfing looks like. Notice how the kerfs close slightly on inside curves, allowing the wood to bend smoothly.






Finally, I have a closeup of the kerfing in the clamps, showing the small amount I left the kerfing proud of the sides during the glue-up. The instructions say to make this small reveal about 1/32". No idea how close I am to that but it looks fairly good, anyway.





These last two pictures are of the glue-up underway, showing how I laid out the kerfing on the side while clamping. Also shown is a photo of the back with all clamps in place.






After this was done I had some time before my wife and boy came home. The next step in the instructions is to layout the braces on the top and back. However, it recommends cutting up the pattern to make this easier. I'm an engineer and I hate working on an original - it makes it impossible to revert - so I decided to take the pattern/drawing in to the office and make a couple of copies before cutting anything up. The next step after the layout step is to cut the soundhole patch. This step does not rely on the layout on the top so I decided to do this step instead.

The soundhole patch is a very thin piece of wood that reinforces the top at the soundhole. The top is made of bookmatched spruce - which essentially means that it is made of two identical pieces with a joint running from the tailpiece to the neck - and the soundhole patch strengthens the top in the area where the material was removed to make the soundhole. The wood is very thin - almost a veneer, really - and the intention is for the soundhole patch to have its grain run perpendicular to the grain of the top. It's trapezoidal and because the wood is very thin I cut it with my Exacto knife and a straightedge. A few moments of layout and the cuts were made.


The photo on the left shows the layout of the soundhole patch cuts, including the patch itself, the framing square I am using as a straightedge, and the drawing/pattern. The one to the right shows the soundhole patch after trimming with the straightedge and the Exacto knife. I should also take a moment to apologize for the incredibly ugly cutting mat. Darn you, Wal Mart!!!



The final image of the day shows the drawing/pattern, the soundhole patch, and the top blank. The next step, probably on Wednesday, will be to transfer the brace locations and commence to shaping the braces, and to glue the soundhole patch onto the top.