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I was asked to post this old build thread that I did on MIMF. I also posted it on another forum, which is where I have this backup text from. Hopefully it will make sense once you scroll down a bit...


Here’s a new instrument that I’m building. I’m documenting it on MIMF as part of their “$100 Acoustic Challenge”, where you are supposed to build a functional instrument for less than $100, and the one that gets the most votes for their finished instrument wins. As I hate to steer you away from this excellent site, I’m posting it over here as well.

They have a 60 Kb restriction on uploads over there, that’s why the quality of these pictures is so-so. I’m cutting and pasting in most of my text from there too, but I’m cutting out the stuff that is only relevant to the “challenge” etc. I’ll still try to keep the post readable.

Here’s what I wrote:

A local musician asked me this fall if I could build him a Hardanger style arch top mandola, and my first idea for this thing was to make a < $100 prototype for that instrument. Recently he changed his mind however, and he now wants a regular ‘dola instead (honestly, I’m relieved, even if it could have been interesting...). So, I’m still going to build a prototype, but it will be a mandola. I’ve made several madolins over the last few years, but never a mandola, so I’m taking this oportunity to familiarize myself with the instrument.

This is an arch top mandolin, Gibson style, more or less. The scale is close to 420 mm (about 16 ½”, I’ll be using a 24,9” fretboard template without the first 6 frets). The body is 300 mm wide, rims 50 mm, oval hole, X-braced.

I’ll be making this instrument solely with Norwegian wood, which is also a first for me. I’ve used local woods in instruments before, but always together with some, or mostly, foreign stuff.

Today I made a plan, templates, prepared most of the woods, glued up the plates, and hopefully I’ll finish the mould and perhaps bend the sides tonight.

Here’s the plan (I’m an architect and familiar with CAD of course, but for quick stuff like this I prefer to just use pencil and paper if I can).








The back, sides and neck will be birch. I found a 3” board in the reject bin at at a local lumber yard. I just cut sides, backs and neck blanks for 3 mandos from it. The top is spruce, logged right here in my back yard by a local farmer. The fingerboard and perhaps some apointments will be pear. This wood comes from a tree that grew in my pal’s garden, and he gave it to me. I’ll also cut a bridge from it, I think. I haven’d decided if I’m going to use an adjustable truss rod or just carbon fibre. I make my own Gibson style rods and I have nuts from SM. Oh, and I’ll use on of those cheapo, stamped tailpieces.

Here’s the birch board with the mandola template this morning (see the date written on the template!).









The wood is nicely flamed throughout, but there are numerous knots, so getting useful pieces out of it proved to be difficult. I did manage to get enough for 3 instruments, but I’m not positive that they will all be withouh knots or blemishes. Oh well!









Here’s on of the spruce bolts.









I cut it into tops that have been drying in my shop since April this year. I prefer to store my wood longer before I use it, but it is nice and dry so I don’t think I’ll have too many
problems.

So, that’s enough chit chat for today, off to the shop!






Here’s the rim in the mould, with spruce neck block and plywood tailblock (both from the scrap pile, of course...). Birch is a pleasure to bend, BTW, even if it is fairly flamed, like these were. I used no water except a little right on the neck area, and the sides are 2.2 mm thick. I don’t have a bending jig for mandolin sides, I just use the old steel pipe and torch method.









The top was jointed and glued (with hot hide glue) yesterday. Today I trimmed it to size, levelled the bottom and did the router table and Safe-T planer thing on the perimeter, and brought this part down to 5 mm or so. Here I’m beginning to jack plane the rest of the top.








After the rough shaping I use finger planes and finish up with scrapers. For this final part like to use a strong directional light, as it makes it easier to see if all the curves look nice. For this instrument I only made one carving template, the rest of the geometry I just checked quickly against the plan and sort of winged it...








Here’s how it looked after I sanded it








I then put a 15 mm forstener bit in the drill press and mounted a bolt (with a smooth head) directly below it, and set the depth stop to 6 mm. Here’s the result.








I use a carving spoon and finger planes to remove most of the wood. This is my shop made measuring gauge, which is nothing fancy, but it works just fine.








Finally the inside of the top is scraped and sanded smooth.








Just had time for a little work on this today, and I decided to work on the back. It was glued up (with hot hide glue) the other day, so today I started by levelling the bottom. This nice old Spiers plane works has no problems smoothing out “difficult” grain such as this.








Like I mentioned in one of the first posts, the birch had quite a few knots and blemishes, but I had cut around most of them. There was one present in this back too, but it was I was pretty sure it wasn’t very deep, and that it would soon be gone when I started carving the outside curves. Wrong! It was much deeper than I had hoped, and as the plate was nearing its final shape, the knot was still very much there. Uh-oh...








Would you look at that!

So, I’m trying to decide if I should join another back, or if I should drench this one with CA glue (or something?) and hope that it does not pop out. I don’t see any signs of it on the inside now, but I’m not sure how deep it is, really.

But perhaps it would look kind of cool, if the instrument is otherwise nicely made. Kinda like that pallet guitar that Taylor made, or Benedetto’s “lumberyard special”. After all, it
i is
supposed to be a prototype, and perhaps in the context of a < $100 instument it would be fitting, somehow.

What do you guys think?

_________________
Rian Gitar og Mandolin

Thanks for the suggestions! I am leaning towards either keeping the knot as is, or making another back. I only have about two hour’s work in it so far, and I’m not going to spend a whole lot of time fixing it. I did glue up another back, just in case...

Instead, I turn my atteniton to the neck. The blanks I cut were roughly 75 x 75 mm, so large enough for a one piece neck if I don’t make the headstock too wide. I start by truing up one side and bandsawing out the profile, then the fingerboard and headstock surfaces are trued up on the edge sander.








Instead of messing with a compression rod, I have decided to use a carbon fibre truss rod. It will cost a bit more, but I will get two out of a 1/8 x 3/8 x 18” if I chop it in half. They cost about $10 from LMI, so I’m adding $5 to my budget. Expensive stuff!

To put the carbon fibre as far back in the neck as possible, I attach a 4.5 mm piece temporarily to the nut area of the neck, and cut the truss rod slot on the table saw.








That means I will need a filler strip over the carbon fibre, so I slice a piece of birch to size so it fits over it. You can see how the slot is cut at an angle.

BTW, this neck blank is flat sawn (violin style), so it will show its figure more or less on the quarter towards the player.








The truss rod is cut so it matches the headstock angle. This will reinforce the headstock / neck transition (instead of making it weaker, like a traditional truss rod nut tunnel). I glue in both the truss rod and filler strip with West System epoxy. Sorry for the messy glue up...







As I mentioned previously, my plan is to use some pear wood that was given to me for fingeboard, bindings and details. I got the logs about a half year ago and only split it open then, I never got around to debarking or slicing it up into smaller pieces, as I had no specific plans for it at the time. I sure hope it is dry enough by now...

Here I have nailed a length of the half log to a slave board so it can be resawn.








Pretty cool colors, huh? I wonder if I can use that contrast somehow...?








Perhaps something like that...?








Yeah, that’s it!








As for that knotty back, the more I worked it, the less I liked it. I wasn’t so much the knot, I wasn’t entirely happy about my own carving either, so went ahead with the other one I glued up. Don’t worry, this one is not without its own cosmetic problems, it even has a knot that is almost as prominent as in the other top! So I think it will fit the “vibe” of the instrument just fine, and more importantly, this carving I can live with.

Whew! Good thing I enjoy carving mandolin plates...

_________________
Rian Gitar og Mandolin

I have been swamped with other commitments for the past two weeks, but I finally got some stuff done today.

First task was cutting the soundhole. I made a paper template of half an oval, which I mirrored over the soundboard centerline. Next I bored some holes within its outline, and pulled a coping saw blade through one of them.








Cleaning up the soundhole edges with a sanding drum in the drill press.








I then sliced up some pear and birch on the table saw, and thicknessed it on the drum sander until I had some veneer for purflings and bindings.








Here’s my rosette cutter, a modified a cheap drill press fly cutter that registers off the soundhole edge. The cutter must be honed really sharp to work well.








Here’s one of my dearest flea market finds, a vintage Norwegian Kongsberg 1/8” chisel. Here I’m using it to dig out the rosette rabbet.








The birch and pear veneers (and a thicker center piece, which I bent on the hot pipe) are inserted into the rabbet, clamped down and drenced with CA glue. The rabbet was sealed with shellac to avoid possible stains first.









The rosette is levelled with a finger plane, and finally sanded flush.









Finished rosette. Not nearly perfect, but good enough for a prototype, I think... One thing I forgot as I was installing it, was that the top edge of it will
i not
be totally covered by the fingerboard, because it will be cantilevered (or ‘floating’). I’m not sure how visible the ugly joint will be, if it bothers me too much I may have to do something about it...









I decided to make solid linings for it. Here’s some leftover birch I sliced on the table saw, I think the pieces are about 5 mm thick.








Rounding one of the edges over with a block plane, and sanding it smooth afterwards.








They bent fine on the hot pipe.








Installing the bindings. The C-clamps are handy where I need a little more clamping pressure...








Making the X-braces now. I have spilt and sliced up some spruce (Norwegian, of course), here I’m tracing the profile of the inside of the top onto the side of the brace.








Planing away the waste with a black plane and a simple bench hook.








After careful fitting of each brace, I cut the X-brace lap joint. When the fit is nice, I glue it.








And finally the X-brace it is glued to the sound board with hot hide glue.









As I’ve never made a mandola before, I’m pretty much winging it when it comes to... well, a lot of things! I am taking notes as I go along though, so if it folds I may have some idea why...








Using the go-bar deck as a clamp when the top is glued to the rim.








Tada!








Some work on the neck again, now. I’ve sliced up some of that pear wood for headstock back and front veneers, and I thickness them on the edge sander.








Most of the wood from the back of the headstock is removed with a Safe-T planer.








The headstock / neck transition is shaped on the idle drum end of my long belt sander.








Lastly things are smoothed out with a scraper.








The back veneer is bent on the hot pipe to confrom to the headstock / neck transition curve. Finally both veneers are glued to the headstock, with registering pins and appropriately shaped cauls.

_________________
Rian Gitar og Mandolin

Some more neck work today. The first operation after taking the clamps off the head is to thickness the neck shaft. I do this by shimming up the nut end of the neck as much as I want the taper to be, and running it under the Safe-T planer.








The next thing is to cut the headstock outline on the band saw. On mandolins, it is common that the angle of the corner of the “ears” and front of the headstock is at a right angle to the plane of the body, not the headstock itself, as on guitars. To accomplish this, I need to hold the neck steady in the proper position while I’m cutting.








Cleaning things up with sanding drums in the drill press, the same angle must be maintained.








The traditional neck joint for these instruments is a dovetail, which is sort of tricky to do well. On the outside, the joints are indistinguishable if done well, except for the straight sides on the tapered joint; the dovetailed necks are often have an elegant concave shape on the side of the heel. Anyways, I’m too chicken for that. I’m using a straight tapered joint (as described by Siminoff in his “Bluegrass Mandolin” book), which will be glued and doweled. I believe it is at least as strong as the dovetail, there’s more gluing surface. They are no fun to take apart, though...

So, this end of the neck needs to get its final shape before it is glued in, and that is easy to do with a band saw and an edge sander.








I saw out the mortise in the body and chisel out the waste. Here’s how it looks, freshly sawn. After this, I use chisels and sanding sticks to get make the joint as nice and tight as possible.








Testing the fit... (no, the shavings are from another project!)








Finally the neck and body are glued up on a simple fixture that aligns them sideways, and it has a “cradle” that elevates the body the right distance for a proper bridge height.







Dennis, now I have that 10 CC song as an earworm "...I don't like reggae, I love it...". Thanks a lot!

So, the neck is secured with a couple of plugs (in holes that are drilled straight down, to accommodate possible future removal), which are glued in.








With the neck joint sorted out, I can glue on the back. I should probably make a bunch of spool clamps or something, I have to use just about every clamp that I have of that general size to get a good, even clamping pressure. Crowded! Removing glue squeeze out through that oval hole is no fun, so I’m careful about using just enough glue, and I’m using tooth pick sized registering pins at both head and tail blocks so the back won’t be skidding around as attach the clamps. I’m using fish glue for this operation.








I won’t be using any binding on the back, which means I have to be extra careful not to mess up anything when I trim the overhang. I usually use a flush trimming bit, but on this one I just whittle away with a sharp chisel, to play it safe. It goes pretty fast.








Scraping the sides with my trusty Sandvik scraper.








Here’s my setup for cutting binding rabbets on mandolins. I do this on the router table, with a shop made fixture. I used to use a the binding cutter from Stewmac, but this system allows me to use a ¼” downcut spiral bit, which cuts much cleaner. I based mine on pictures I’ve seen on one used by Lynn Dudenbostel.








Here’s a closer look. The bottom part of the jig is screwed solidly down in holes that tapped into the the steel plate that holds the router. The part with the router bit protruding from it is where the top will be resting when I cut, and this elevates the instrument off the table enough so its arched plate won’t interfere with the angle of the cut. The top part can be slid in and out for different binding widths, and is secured with the wing nut.








Action! I should probably drill out the hole for the bit some more to make dust collection more efficient... I’m doing the cutting in about 3 passes, taking only about 0.7 mm per pass, to avoid any unpleasantries.









Checking if the binding fits... As you can see, the rabbet is quite clean straight from the cutting, and there is no manual cleanup. Now, if this were an F model (or H, since this is a mandola), with scroll and points, it would be a different story.








I give the soundboard a quick wipe with shellac (to avoid lifting spruce slivers and discoloring), and install the bindings with CA glue. I like to use this packing tape to secure the bindings.







I took some pictures when I was making the fretboard. Nothing new here for most of you, but since I have now have all these pictures...

I don’t have a fretboard template for a mandola (does one exist? I haven’t checked), so I’m using my 24,9” guitar one, and using the 7th fret as my nut position. This will give me a scale of about 421.1 mm, or 16 ½” or so.








That means I can quickly cut the first 17 frets, but that is far as this template goes. There is still a bit of unslotted fretboard real estate...








...that will have to be done manually. I found an online fretboard calculator, punched in my “weird” scale length, and got the numbers for the positions of the remaining slots. Here I’m marking these on the fretboard with a marking knife.








Sawing along a square. I sure don’t miss doing whole fretboards this way!








After marking the fretboard taper from a centerline, most of the waste is cut away on the band saw. I sneak up on the line itself with a sharp plane.








I’m going to use a 12’ radius on this board, which is roughed in with the plane, and finally sanded with a straight block (jack plane body). I check my progress frequently with a straight edge, calipers on the outside edges and the fretting template.








Pressing the frets in with the drill press. I use fish glue to lube the frets, and use the depth stop to keep the pressure on the frets for minute, while I wipe off excess glue and put glue on the next fret. The idea is that this will help the fret set better as wood fibers around the barbs relax.

Missing some pictures here, but after all the frets are done, the excess is trimmed, ends filed and corners beveled, I bend the board backwards, until the board stays flat on my reference surface (jointer bed). I then use a 100 mm heavy steel profile as a caul, and hammer the frets lightly. I also check their tops thoroughly with short and long straight edges, to make sure they are all evenly set.

When everything is nice and true, I glue the board to the neck with epoxy, and pray that it will stay that way...






So, preparing things for the fingerboard. A fretboard extender is glued on (with Titebond, for convenience), and clamping is done with a screw, diagonally into the neck block. The screw will be removed before the fingerboard is attached. I also glue in other bits and pieces around the neck joint. The 12th fret cross piece is pear, everything else is birch.








My daughter checks in, and poses for a shot...








Levelling the fretboard extender with a block plane...








...until it is nice and level








Shaping those whatchamacallits with a small rasp...








...and the neck with a larger rasp...








...until it looks about right, and according to plan.








Front.

Now, I really have to start thinking about a tailpiece, that cheap stamped Gibson style one I had in mind is too small (the strap button would not be centered on the butt), besides it just doesn’t look right on this instrument. Hmmm, how about some more of that pear...? I also hate the thought of putting those “budget” Grover tuners on, so I think I will use a nice set of Gotohs that I found on the bottom of a drawer. I also found the invoice, and it seems I paid $62 for them. I didn’t put things like glue and finishing materials in my preliminary budget, so I may be getting close to the limit though. So be it.








I’m going to string this mandola up ”in the white”, so I can make the final adjustments before the finish goes on. It makes it a lot easier not to ding up the new, soft finish when fitting bridge and nut etc. (DAMHIK)

This is my tuner dilling jig. I’ve used shop made wooden ones before, but this one just makes life easier (and the tuners work smoother). Thanks, Stewmac!








Fitting a nut before the final shaping of the neck is always a good idea. It saves the fragile edges of the neck around the nut from tear outs, plus you get a perfectly fitting nut.








Like I mentioned before, I’m planning to make a on piece pearwood bridge. I know pear has been used for bridges for other instruments in the past, I believe they are popular for lutes (?). Anyways, I’m going to give it a try, and I’ll see if I can make it work with some of that sap wood on top... BTW, pear wood smells quite disappointing when machined; not “fruity” at all!








Here’s the bridge after being fitted to the top. It is quite oversize, but it is easier to cut them down than add to them after the fact! I’m going to string it up more or less like this, let the instrument settle for a couple of days, and then cut it to its final size. This bridge is both wider and thicker than a standard Gibson type adjustable ebony mandolin bridge, but is already about 15 g, or about 1 g lighter than an adjustable bridge that I weighed (including hardware).








Headstock, with tuners and strings on. I’ll countersink and add the bushings after finishing. I think the color of the buttons matches nicely with overall color scheme of the instrument!








Back of the headstock








Varnish next!





I haven’t had much time to work on this instrument lately, but it has been sitting around “in the white” with strings on for some weeks, so it has settled in some. Everything seems to be stable, the neck is nice and straight. Its new owner came by and played it a little while ago, and we tweaked the neck profile just a hair. It sounds surprisingly nice, if I may say so!

My plan was to give it a slightly darker toner under the top coat, but I was talked into leaving it “naturally blonde”, which is appropriate for that Nordic theme, I guess... I gave the top a quick and dirty French polish before brushing it, and the rest of the instrument, with a thinned coat of Epifanes. This is how the front looked after the the second, slightly less thinned, coat.








...and the back. That varnish sure pops the grain nicely, unfortunately it also highlights boo-boo’s equally well!








The varnish seems to harden just fine. I am used to working with lacquer, so the application takes some getting used to, though. One thing I really like about this material is how easy it is to sand. I managed to get it fairly level after about 4 or 5 coats, wet sanding with 1000 grit. I then decided to rub on some tru oil, and it seems to smooth everything out nicely. This is after the second, and hopefully final, coat of tru oil.

BTW, I'm also rubbing on some tru oil on the finger board. It got grungy real fast when I was playing it in the white, so I'm hoping this will keep it a little nicer looking, for a while anways...








The back






…and we’re done! Just in time too, but hey, story of my life and all that.

Front








Back








Front








Back








Side








Headstock, front






Headstock, back








The maker, taking her for a spin.







The final budget
Spruce: Free
Pearwood: Free
Plywood: Free
Birch : $3
Tuners: $62
Fret wire: $2
Carbon fibre truss rod: $5
Side position markers, end pin, wood plugs, nut: $5
Finish , glue etc $10
Tail piece: $10
Total: $97

Thanks for looking!

_________________
Rian Gitar og Mandolin

Arnt, I got all excited when I saw the title and who posted it. I was ready to pull up a chair and watch another great build thread unfold. I was a little disappointed to see it was you old thread, only because I had already followed it while you were doing it. But. . . it was great just looking through it again. Thanks for re-posting over here.

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Yes, Arnt, thanks very much. I still find this thread very informative and I get new ideas every time I look at it.

Thanks for sharing this thread. I found it very interesting and am taking away some ideas.

Max

_________________
Max Bishop
Brighton, Michigan

Hey Arnt, thank you for posting this. I also remembered following this thread over on the MIMF. Your common sense approach makes great sense to me and has given me a number of good ideas for my mandolin project.

_________________
Steve Smith
"Music is what feelings sound like"

Beautiful Work . I think the Knot just adds the true character of the wood .

_________________
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Very nice, I really enjoy using local wood in a build.

Thanks very much for posting this, Arnt!
Very detailed information and great pictures.
Regards,
Dan

_________________
wah
Wah-wah-wah-wah
Wah

Arnt, thanks so much for this thread. I remember seeing and enjoying it years ago on the MIMF.

I'm currently planning a mandola build, and I have a question for you. You mentioned that the perimeter of your top is 5mm, but what is your total top height, from the base of the top to the top of the carve? It's a little trickier finding this kind of information on mandolas compared to mandolins!

Thanks for your help!

Excellent stuff, very clean build! Please post a video sometime so we can hear it.

_________________
"Act your age, not your shoe size" - Prince

I was wondering the same. How much arch does a mandola have? 20mm? 18mm? 15mm? Hard for me to scale down from a 43cm wide guitar.


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