Jim McConkey's Flood Mandolin Twins

[Jim McConkey]

Thanks, Mario! Setting the neck, IMHO, is probably the most daunting part of any instrument build (maybe why I primarily build duclimers, which have nothing to set!). I can draw accurate pictures all day, but I can't guess how much the neck will bow from string tension and how much the top will deform, however minutely. I have no idea how guitar makers get it right with no option for adjusting the bridge.

[Jim McConkey]

Sorry for the delay. Work and other things caught up with me last week, not to mention the lack of a couple vital tools. The next task is inlays, and although I have located my Dremel, routing base, and inlay bits, the collets to hold the bits were nowhere to be found! I am not quite 2 hours round trip from the nearest big hardware stores, and I don’t get down that way very frequently, but I finally did. Lowes carries them around here, but Home Depot does not. For a lot of things like this, Amazon is much quicker than actually going to a store.

I found some fingerboard dots I had left over from a previous job turning a diatonic dulcimer into a chromatic one, and they just happen to be blue. Perfect! They are 5 mm diameter by 2 mm thick, and I thankfully have a 5 mm brad point drill to match. But with a lousy drill press, how do I get the depth just right? Laminate floor spacers to the rescue yet again!

I put the fingerboard face down on the drill press, and set the depth stop so that the flat part of the bit (the edges stick out further on a brad point drill) sat firmly on the fretboard. My floor spacers are 2 mm thick on one side, and 5 mm on the other, so I simply used two to hold the fretboard, now right sided up, 2 mm up off the drill table. Perfect 2 mm deep holes every time!

A drop of superglue, press in place, and the fingerboards have dots.

[Jim McConkey]

For the wave inlays I am using Ablam (sometime Abalam). This material is actual shell, CNC milled into very thin slices, color matched, then epoxied together into sheets. This stuff has gotten ridiculously expensive in recent years, but I got a big piece off e-bay quite a few years back for next to nothing. The piece I have fortunately has a lot of blue in it, which makes it perfect for water.

My Ablam is only 0.01” / 0.25 mm thick, so I cannot cut it directly without it disintegrating. Cutting it requires a trick Amy taught us years ago in the MIMF inlay class. It has to be glued to a backer first, and I just used a cutoff of my oak sides, 0.080” / 2 mm thick. Plain Elmers white glue works the best, but I didn’t have any, so I used Titebond. I glued the pattern on top with the same.

A small jigsaw with a very fine tooth blade makes cutting easy. The Pro-Cut wax makes it even smoother. I could not have cut these inlays without the backer! I clamped my inlay cutting board to the workbench and start sawing away. The blade is so small that sharp bends are easy, and there are so many teeth per inch that cutting is quite smooth and controllable. The cutting board has a long tapered slot with a 1/4” / 6 mm hole near the broom handle I used to thicknessing my tops, which gives the workpiece lots of support while sawing.

Before separating inlay from backer, I used a fine scribe to trace the design onto the head.

I dropped the inlay assembly into a shallow tray of water to separate inlay from backer. With Elmers it only takes a few minutes before backing, inlay, and pattern all just slide apart. I had to soak the Titebond overnight to get it to release, and even then had to use an X-acto knife to help it along. I will not use Titebond for this again!

The lightning bolts I made out of tiny scraps left over from the old MIMF inlay class. In comparison to the Ablam, the normal shell was a really lovely sea breeze to cut, even if the piece was very small.

Since the Ablam was so thin, there was no point trying to route out a cavity. I used my violin makers knife and a small wood carving knife to barely scrape off the floor finish and then just a tiny amount more. While trying to fit the delicate Ablam pieces, they both broke, but thankfully in places it was easy and relatively invisible to refit them.

I started to route the deeper lightning bolt cavities, but even my tiny inlay bit was too wide for most of it, so I ended up cleaning out those cavities by hand as well.

With the cavities all cut, a couple drops of superglue and the inlays were in place. There was unfortunately some squeezeout from the waves that did not clean up as cleanly as I would have liked. This is one reason the pre-finished heads were not ideal, but it is desirable for other reasons, so I will just have to live with it. The end result was sort of under-stated, but the waves flash bright blue when the light is just right.

Next up - routing for binding. My Siminoff-style binding attachment cannot do thicker bindings. I have a precision router back for my Dremel, along with the edge following guide, but the screws to attach the two have mysteriously gone missing, so I'm back on hold for a while. I e-mailed Stew-Mac's ever-helpful tech support to find out the screw size, and I will probably have a reply before I even get up tomorrow, but it will still take me some time to get the right machine screws. I may start installing the frets in the mean time.

[Matthew Lau]

Hey Jim,

Any updates?

I stumbled on this thread, and have to say that you're a great guy.
Hope all is well.

[Jim McConkey]

Work, an aging father, and life in general all conspired to close the window of opportunity I had this summer. I hope to get back to it shortly, and, with any luck, finish in time for Christmas.

[Gordon Bellerose]

Yep. I'm still reading with interest too Jim!
My guitar work this last 2 months has been limited to a few repairs that came in.
Wife had major surgery and I've been the cook and clean guy.

[Bob Francis]

I'm watching as well.
You are a talented guy.

[Bryan Bear]

Yep, lots of us watching with interest.

I know how it can be to have long pauses between productive workshop sessions so no pressure.

[Jim McConkey]

You guys are too kind. I don't have half the experience of most of the member's here, I'm just not afraid to jump in and try things.

In any case, I have actually made a little progress lately, having fitted the bindings and routed the binding channels. I will get pictures up soon. But then I will be staining, and that will take a while with nothing particular to show while it dries.