Jim McConkey's Flood Mandolin Twins

[Jim McConkey]

The neck needs to be attached soon, so finishing it is the current priority.

I traced the head of my flat top mandolin onto a sheet of paper and copied it a bunch of times, and then went to town trying to come up with a suitable design. I have some Ablam (sometimes Abalam) scraps that have a lot of blue in them, so my mind immediately went to waves, in keeping with the flood theme. The famous Japanese “Great Wave of Kanagawa” sprung to mind, and I have seen it executed fantastically in inlay, but it is complicated and tedious, and big as it was, it was only one wave.

So I settled on a triple, somewhat simplified wave. Not only does it imply a lot of water, but it can also be seen as the stylized letters M (for my last name), N (for my wife), and S for the Searcys.

Now for the headstock shape. I really liked the bottom middle design with multi-color clouds and lightning, which I had intended to do intarsia-style using woods including my previous water-damaged shop floor. So I mocked up the design with photocopies of the woods I had planned to use laid on the actual head, but unfortunately the design didn’t work in practice because the light clouds were just too much contrast from the dark headstock. There was also the practical consideration of wanting to keep a thin border of dark at the top around the light clouds, which would have been nearly impossible to keep intact during routing.

So I settled on a design more like the bottom right left, with a cloud-implying shape, a lightning bolt, and the triple wave beneath.

[Jim McConkey]

I covered the already-finished face of the head with masking tape to protect it. I also put masking tape on the back so I could trace the shape, since it will be far easier to cut on the bandsaw face-down. After cutting the head to shape with a 1/4” (6 mm) blade, it was back to the drill press with sanding cylinder to clean up the sides. The tight curves of the top had to be cleaned up with small files.

Just as I was trying to figure out how to drill the tuner holes, I remembered that I had won an older StewMac mandolin tuner jig here many years ago, in one of our auctions. Finding it was another issue, but I finally did. The version StewMac sells these days is all metal, and mine is some high density wood and phenolic, but it still just as useful.

From the head from my mandolin currently being repaired, I figured out where the top and bottom holes should be, then drilled the bottom hole only half way through with a 1/4” Forstner bit. The jig is then placed in position and a supplied steel pin fits tightly through the bottom hole of the jig and into the half-drilled hole, then the upper hole is started.

You have to remove the jig so the bit can get rid of its waste to drill the hole, then put the jig back with pins in both the upper and lower holes. Then the two middle holes are started, the jig is removed, and the holes can be continued, all halfway through. This procedure ensures the holes will be drilled as accurately as possible. If you have to lay out the holes manually, the spacing is 23.0 mm. Forstner bits make very clean holes going in, but are not as clean when exiting, so I switched to a regular 1/4” twist drill and backing board to finish the holes. The tuners fit perfectly!

[Jim McConkey]

Now for the arduous and nerve-wracking step of fitting the neck. Siminoff shows many fine jigs in his book and on YouTube, but they are geared for production, and I have no idea when or even if I will build more mandolins, so I decided to attempt it by hand (well, mostly). First step was to cut the tape on the heel end of the neck. Nothing fancy about this, just two cuts at the same angle, straight along the sides. The taper is fitted to the block for this design, which is opposite of a traditional dovetail. If this joint had been cut on a bandsaw, the neck block would have been elevated, so that the cut is deeper on the bottom than on the top. Most plans show this to be about 6 degrees, but mine is a little shallower since I am not strictly following those designs.

My bandsaw cannot be counted on to cut straight, so I cut the two outside tapered cuts by hand with a razor saw, then used the bandsaw to kerf the inside of the joint. Using a hand jigsaw, I cut out the fins and cleaned up the joint with a sharp chisel. I had practiced making the tail block in a scrap of wood, but the real joint still took a lot of finessing.

The second joint seemed to go much smoother. I think I finally have both necks close to right. It is starting to look like a mandolin

[Jim McConkey]

One last step today, glue in the linings for the back.

Tomorrow hopefully the backs will go on, and the necks will be glued in.

[Gordon Bellerose]

Jim. I'm both dismayed and relieved.
Relieved that I didn't make the body cutting mistake, and dismayed that you did.
I will be watching how you correct this one. If you have a sliver of the same wood, that might make more sense to me. But it may be hard to fit and glue it.
But too thick a binding might make the body look a bit clunky also.
Perhaps some purfling? Is that the right term?
Decisions......

[Jim McConkey]

I had the same worries thick binding. Purfling could be an option, but I don’t happen to have any, and it is not easy to make on short notice. However, being forever behind cleaning up anything, I checked by the bandsaw and found I still have the exact cutoffs from this top, minus a saw kerf. They fit fairly well as is, but need to be cleaned up carefully with a sharp knife. The match line will be fairly clean, but the repair will not be quite invisible. I still think this is the best way to go. I hope that when bordered with a dark binding, it may not be so visually obvious. If this had been a close-grained, uniform spruce top, it would have been much easier to slice off a straight chunk on the side and glue on a nearly identical piece. Ah, the joys of using unique wood!

[Jim McConkey]

Life keeps getting in the way! At least I got the backs glued on today. I put small brads in the neck and tail blocks (works much better than staples!) to quickly get the backs and ribs aligned. Before starting to glue, I adjusted all my spool clamps to be only a couple mm bigger than the assembled thickness, which means I can put them on, spin the wingnut 2 or 3 times, and they are tight. I heated the backs and ribs as usual with a small hairdryer until they were noticeably warm to the touch, then quickly put glue on the ribs and back and assembled. Because mandolins are not that thick, I was able to use my spring clamps very quickly to get a good tight fit between back and ribs, probably not 10 seconds for the whole mandolin. That gave me plenty of time to replace them one by one with the spool clamps. And since I had to split my spool clamps between two mandolins, the gave me some extra clamps as needed.

After drying over night, I will trim the backs to the sides, and repair the one top before binding. I have a few last-minute things to finish on the necks, and they will go on tomorrow, and the instruments will finally be whole.

[Jim McConkey]

Back to the terrible error from a couple days ago. In too much haste, and marking out of the form, I cut too much off the sides of one of the tops, leaving too much room for the binding to fill. I had thankfully found the cutoffs next to the bandsaw.

It took a couple hours, but I cleaned up the sides and the cutoffs with an X-acto knife, plane, and sandpaper until it fit as well as I am capable of fitting it. I marked the right side with a double line across the top and cutoff, and the left side with a triple line, so that I could quickly and repeatably get back to the proper alignment. A little hot hide glue and a lot of tape held the cutoffs tightly in place to dry.

When the tape finally came off, it was better than I thought.

After cleaning up the edges and scraping over the gap to make the top and cutoff exactly the same height, I have trouble seeing the splice from over a foot away. As long as the patches don’t blow out when I route the binding ledge, this should work just fine. Just to be sure, I think I will pre-cut the ledge with a gramil before I get out the Dremel.

[Jim McConkey]

I trimmed all the top and back sides to the rim with my finger plane, except in the area where it curves into the neck. That area is always a problem. Then I remembered my sanding cylinder for the drill press. It cleaned up the curved areas nicely. I just had to be careful not to press too hard or hold the instrument crooked.

I also didn’t mention much about carving the necks. When I was just starting out, this was the most intimidating part of the whole building process, as other newbies have said here. But after only one neck, I was a convert and now agree with most experienced builders that it is one of the more enjoyable parts of the build.

A sculptor friend once told me that scuplting was easy – just remove all the material that is not part of the final sculpture. I can’t even draw a face. Don’t try to ask me to take away all the parts that are not a 3D face, but for some reason necks are easy. Just slide your hand up and down the neck and it will be immediately obvious what parts still need to come off. I used no templates on these two necks, and they are remarkable similar and they feel just about the same to me.

My main tool for carving is a microplane rasp. This one is mostly flat with curved corners, but I have an arched blade for it that I have not seen in a while. Each “tooth” is a miniature plane. They can hog a lot of material off quickly, but are really quite controllable. A bastard file (half flat, half curved) is necessary for carving the heel. The strip of sandpaper comes in handy for sanding the curved surfaces – clamp the neck down, hold one end in each hand, and saw away. And I can’t believe I completely forgot to include my most indispensable tool, a scraper. I invested in one of Al Carruth’s Ultimate Scrapers (the big oval one), and it was some of the best tool money I have ever spent! I use it constantly.

[Jim McConkey]

Well, it is now July 5th. Happy 20th Anniversary, MIMF!!!

But today is also supposed to be the end of the contest. I have already screwed up too much trying to make haste, so I am not going to ruin the instruments trying to rush the final details and finishing just to meet the deadline.

In just a couple weeks, some waterlogged construction lumber and flooring have gone from rough boards to fairly mandolin-like. Have no fear, I will continue this thread until they are done.

[Bryan Bear]

Those look great, this project and theme came together wonderfully. I can't wait to hear them.

[Peter Wilcox]

I certainly admire your progress and persistence, and your ability to make silk purses out of sows' ears. These instruments tell a real life story.

[Brent Bischoff]

Jim, I really like how these mandolins are turning out. I used the same neck joint for my mandolin build. a question for you, with the backs already glued on, how did you pin the joint?

[Jim McConkey]

Brent, you would have to bring that up! Of course that is another major goof. Not having used this kind of neck joint before, I got confused about the order of operations. I am used to binding before putting in the necks, so that is how I was proceeding. I should point out that is still possible to pin from the top, even though that is not the normal way to do it. The effect will be the same, it will just be rude shock if anyone tries to disassemble it in the future. However, both owners will have a build log full of pictures, so that should not be an issue.

I am also considering pinning using long wood screws from the top. The screw threads will keep them from rattling at all, the joint will be easy to disassemble after removing the fretboard, and the pinning effect between the neck and block will be exactly the same.

[Brent Bischoff]

Jim, I apologize, I didn't mean to point out a goof . I know all about major goofs from my mando build. One good thing came out of it, I learned how to reset one of these neck joints! Pinning from the top should work. I look forward to seeing the finished results.

[Mario Proulx]

Hmmmm, yeah, the pins had to go in before the backs went on....

Pins --can-- go in from the top of the neck, as long as the fretboards aren't glued. Find the angle that will see the p9n intersect both the heel and the neck block for at least the bottom 3/4" or so. If the neck pocket fit is good, and the heel fits tightly to the back, you don't need full contact of the pins. Just enough at the bottom to prevent the heel from rotating...

[Mario Proulx]

Another option, I suppose, is to get a long 1/8" drill bit, and drill the heel and neck block from the strap button hole, then added a screw. HAve the screw already in the neck block, apply hot hide, and snug it up with the screw.

That said, I'd rather see you pin it from above.

Nice project; well done!

[Jim McConkey]

Thanks, Mario. That is a high compliment coming from a professional mandolin maker like yourself. I still consider myself a beginner after all these years, and there is still a lot to learn and a lot of skills to practice, and I am thankful that everyone here is so free in sharing their experience and knowlege.

The fretboards are not glued on yet, so pinning from the top is still an option, and I agree is probably the way to go.

[Jim McConkey]

Mario or Brent, since the neck hasn't been glued yet and you have done this before, how do you determine the proper neck angle? Siminoff's book shows him using a production jig (that I don't have) where everything is worked out ahead of time. I was thinking that a straightedge laid on the fretboard should just touch the adjustable bridge at its lowest setting, so there is room for adjustment. Is there a better way to do it?

[Mario Proulx]

If you do it that way you'll have the saddle cranked up way high...

Remember to account for the fret height also. Shims taped to the fretboard will suffice. Better yet, install the frets. Now lay your straight edge on it and set the neck angle to roughly 1/32" to 1/16" below the saddle.

The string height will be roughly 1/16" at the 12th fret, which means that if you set the angle to the top of the saddle, you'll be raising the saddle at least 1/8". Yes, that's okay, but if your top is nice and lively and goes down a bit when strung, you're now looking at raising it even further. And it's perhaps just me, but I prefer lower bridge/saddles on mandolins.

Hey! You have two here. Do one each way, and see where that leads....