DIY Workshop: Martin Guitar Kit – Part 8
We took advantage of the summer weather to finally bring our acoustic build project to a close. Huw Price applies the finishing touches…
I’m sitting down to write this final part of our Martin acoustic guitar kit adventure exactly one year since it all began. In truth, it’s only taken so long to get to the end because I’ve been getting on with various other projects in-between, and I complicated things by customising the kit. If I’d just put it together in the way Martin recommends, it would have been a much shorter build, but instead it’s been quite the undertaking!
In the previous instalment I covered the spraying process that gave our guitar its distinctive and unusual sunburst finish. Before getting onto the exciting parts, however, I have to get through all the grunt work involved in bringing nitrocellulose lacquer up to a high-gloss finish.
I’ve covered this process in DIY Workshop several times before and as always, I move through various grades of wet and dry abrasive paper – starting with 800-grit, followed by 1,000, 1,500 and 2,000. From there, I move onto Micro-Mesh and after progressing through 4,000-, 6,000- and 8,000-grit, the finish starts to take on a lustre.
However, I did try a couple of new techniques for this project. With each change of paper and Micro-Mesh, I also alter the direction in which I’m working. So, the 800-grit goes with the grain, 1,000-grit goes across it, and so on.
The tools used in this feature include a polishing mop and mounting pad from Halfords, two reamers, a set of nut files and a home-made bridge clamping caul
As usual I polish up with Farecla G3 compound followed by 3M Machine Polish. This creates a deep gloss effect, but looking across the finish, very fine scratches are still visible on the surface. For relic finishes it looks fine, but I’m aiming for greater finesse here and so I decide to try mechanical buffing.
Pro luthiers and guitar manufacturers use buffing wheels, but since I don’t have one, I use my hand drill with a foam polishing mop fitted to it instead. You can buy these mops and the drill mounting attachment from Halfords, and they’re pretty cheap.
I have been wary of using power tools for delicate tasks since the great Washburn parlour orbital sander debacle of 2003. However, I’ve gained a bit of experience since then and the decision pays off.
I apply liberal quantities of Meguiar’s Scratch X compound to the guitar, dab it around with the mop and then start the drill. I go with a moderate speed, very light pressure and I keep the mop moving to prevent heat build-up.
Quite quickly those annoying fine scratches begin to disappear and when the excess compound is removed with a clean microfibre cloth, the guitar begins to look even shinier. After about 30 minutes I’m done, and with some MusicNomad F-One Oil on the fretboard, the guitar looks pretty good.
The bridge arrived oversized, so the ends are trimmed off to match the six-inch Martin standard
Bridge of size
Before getting onto the serious business of gluing the bridge in place, I first want to discuss the bridge itself. You may have wondered why the masking tape patch I attached to the bridge area prior to spraying is rectangular. Well, here’s the story…
The kit arrived with a Richlite bridge and fingerboard due to the difficulties in shipping rosewood internationally. While I’m sure it would have done a fine job, I never intended to use it, as despite the current CITES restrictions, rosewood guitar parts are still available from European suppliers.
I used the Richlite ’board as a template to make my own from a rosewood blank, and added a ziricote peghead overlay – and after that, it was clear that only a rosewood bridge would do.
A belly bridge is duly purchased for less than £10, and it’s really nice. However, as the project has progressed, the belly bridge started looking wrong on this guitar.
Searching for a ‘rosewood pyramid bridge’ online turns up something suitable, but when it arrives it turns out to be about 17mm longer than a Martin bridge. Even so it looks so much better and the cost is negligible.
The saddle slot is a lot wider than Martin’s, so the saddle supplied with the kit cannot be used, but Allparts UK supply a thicker bone blank that will also allow a bit more scope for intonation adjustment.
The trimmed bridge is filed and sanded to restore the pyramid shape, albeit with a small difference
Getting in shape
When fitting acoustic bridges, you’ll most likely find that the bridge base is flat, but the soundboard is arched. Rather than force them together using clamps strong glue, it’s better to sand the bridge’s underside so it conforms to the soundboard curve.
The procedure is the same one used for fitting floating bridges to an archtop. I tape 180-grit paper to the soundboard, directly over the area where the bridge will be attached, place the bridge on top and move it back and forth along the length. If you mark the base with pencil lines, you’ll know you’re done when all the lines have vanished and you’re left with smooth rosewood.
I address the length issue by sawing off the ends off the bridge using a mitre block. This changes the shape of the pyramid, so I use a file and a sanding block to reinstate the pyramid shape. Rather than meet at a point in the centre, I’m left with a centre line due to the changed dimensions, but I like the look and since it’s a bit different to a traditional Martin design, I decide to keep it.
The re-shaped bridge is sanded smooth and after protecting the base with masking tape, I apply some brown shoe polish to enhance the colour, and buff it out.
Sanding the underside of the bridge to match the soundboard curve allows it to contact the wood without the ends having to be clamped flat
It’s time to remove the masking tape from the bridge area, so I make a shallow incision in the centre with a craft knife, slide the blade under the tape and lift. It comes away quite easily, so I tear across to the edge and begin peeling it off.
The masking tape is peeled off towards the centre to prevent the finish from being torn off the wood
At all times I aim to pull the tape away from the edge and towards the centre, because I don’t want to peel finish off the wood. It’s stressful but nothing untoward happens and I’m left with very clean edges. The tape lifts up some spruce fibres, so I lightly sand away any loose pieces.
After protecting the soundhole edges with taped on kitchen roll, the bridge is placed in position and clamped. Unfortunately you do need specialist clamps for this, and the three I bought years ago cost over £30 each. However, I notice that Axminster sells an implausibly named ‘Deep Throat G Clamp’ for just £8. I haven’t used one, but it may work okay for you.
Paper towels protect the finish as the bridge is about to be held in position for final measurements and index pin location
This is when measurements and alignment must be checked and re-checked, because you only get one shot at this. Once I have verified that all is good, I score around the bridge with an ultra sharp blade.
The reason being that it’s common practice to make the bridge patch slightly smaller than the bridge and then remove a millimetre or so all around the edges. This ensures the bridge base is glued onto bare wood with no lacquer underneath, for the strongest possible joint. Unfortunately the lacquer proves more inclined to flake than cut. I just about get away with it on this occasion, but if I ever do this sort of thing again, I’ll simply make the masking tape patch identical in size to the bridge.
With the bridge finally clamped in position, I drill 2.5mm holes through the bridge base and into the spruce beneath. The bridge is removed and I superglue two short lengths of 2.5mm dowel in the holes to serve as index pins. These will stop the bridge moving when it’s being clamped and I’ll be able to drill straight through them when I’m fitting the bridge pins.
Before applying vintage-appropriate hot hide glue to the bridge, I score the underside to provide a key for the glue. I also tape a clamping caul in position under the bridge plate. With two clamps place in position, I do a couple of practice runs and then go for it – adding a third clamp in the centre after the two end clamps are tightened. A wet cloth takes care of the glue squeeze out, and the clamps are left in position overnight.
Tiny index pins are glued into holes drilled through the A and B pin holes and the bridge’s underside is scored for gluing
Before I can string the guitar up, I will of course need to fit some tuners. Although the die-cast units Martin supply with the kit are perfectly decent, I feel vintage-style open-gear tuners are more in keeping with the overall aesthetic.
This set of Stewart Macdonald Golden Age tuners comes pre-relic’d, and they’re good value for money
Waverlys are wonderful, but eye wateringly expensive and although I’ve had good results with Grover Sta-Tites, I decide to order some relic’d Golden Age tuners from Stewart-MacDonald because they’ve impressed me on B&G guitars and they’re quite affordable.
The bushings are slightly too wide for the holes I drilled in the headstock months before ordering the tuners, so I use a reamer tool to widen their diameter to fit. Really, I should have done it before spraying the finish, but I manage okay. I widen the holes until the bushings sit a couple of millimetres proud of the headstock, then I press them in using a G clamp.
Masking tape strips are placed either side of the holes on the back so I can mark the tuner screw positions. With a masking tape depth stop wrapped around a 2mm bit, I drill 12 pilot holes, remove the masking tape and install the tuners. They certainly look the part and the yellowed plastic buttons even match the binding – great stuff.
Applying masking tape to the headstock makes it easier to mark the screw hole positions
After all the care taken to protect the wood during the build process and the gargantuan amount of effort involved in finishing, drilling six holes through the body is a heart-in-mouth moment. But this guitar requires bridge pins so there’s no avoiding it.
A bridge-sized cutout in a piece of cardboard is placed over the bridge to protect the top. I also cover the body with thick towels. The bridge came with pilot holes drilled part way through, and this really helps as I start with an equivalent sized drill bit.
I use as little pressure as possible while I drill to minimise chip out as the drill breaks through. Then I work my way through a couple more drill bits of increasing diameter to widen the holes.
Bridge pins are tapered, so I use a reamer tool that I bought many years ago especially for doing this job. You can get them from luthier suppliers, but if you search online you can generally find them cheaper on auction sites.
The key is to work slowly and keep checking the fit. Ideally the ring under the rounded top of the pin will end up sitting 1.5mm or so above the bridge. Again, I choose not to use the plastic pins Martin supply and buy some cheap bone pins on eBay instead.
The Allparts saddle arrived slightly too thick and long for the bridge slot – which is exactly what I want. I saw it to the required length and reduce the thickness using a piece of 240-grit paper fixed to a flat surface with double-sided tape. After several cycles of sanding and checking, the thickness is about right and I round over the saddle ends to match the ends of the slot.
With small angled notches sanded at each end of the underside, the saddle is installed and I draw pencil lines onto the saddle along the top of the bridge. With the saddle removed, I use a downloaded radius gauge (www.pickguardian.com) to mark a fingerboard matching curve onto the saddle.
A file quickly establishes a curve across the saddle’s top and I quickly round it over. I leave a lot of saddle proud of the bridge simply to get the guitar strung up – I’m not looking for finesse at this point.
Again cutting nut slots requires specialist tools – namely a set of nut files. They’re not cheap and if you don’t plan on doing this very often, it may be cheaper to leave this bit to a pro. Since I own a set of nut files I do the job myself, starting with the two E strings.
A spacing of 36mm seems about right, and I know it will feel familiar and comfortable for me. The remaining strings are installed, lightly tensioned and held in position with a capo at the 2nd fret.
This allows me to get the string spacings evened out, mark the nut and file four more shallow slots. The moment has finally arrived when I can tune the guitar to concert pitch and – assuming it doesn’t fall to pieces – get an inkling of what it’s going to sound like.Strung up
Tuning is accomplished without any drama and now I have to make the guitar playable. I begin by adjusting the truss rod, which requires a special tool. Martin doesn’t include a suitably long Allen wrench with the kit, but they’re available cheaply online and I use mine to achieve a tiny amount of relief at the 7th fret.
A set of 0.012 gauge Martin 80/20 strings is included with the kit and while not what I usually use, they’re more than adequate for this initial setup. Gradually the nut slots are deepened and I end up lowering the saddle, too. The final hours of this year-long project are a bit of a blur, but it seems that I suddenly have a playable guitar. Barring a bit of nut and saddle polishing, it’s all done.
Earlier in the project, one reader made the not unreasonable point that this is more guitar assembly than guitar building. After all, the neck and neck block come straight off a CNC machine, the sides are pre-bent and the top is pre-joined and routed for the soundhole and its rosette.
However, if what has been done here is merely ‘assembly’, then the same accusation could me made of almost any major guitar company. Believe it or not, it’s the way most of the boutique builders operate, too.
I dare say that many of us would be capable of building from scratch if we needed to, but going with a kit means you don’t have to invest heavily in specialist tools and spend countless hours honing specialist skills that you will seldom use.
I’d argue that making your own fingerboard qualifies as ‘building’ and voicing the top and back has a more significant impact on the end result than whether you do your own bending and routing. If that means sharing the credit with the good folks at Martin, then I’m happy to do it because this is a great quality kit.
But is it all worth the effort? My answer is an unequivocal yes. Granted I spent a little extra on customising my guitar, but that’s a big part of the appeal when doing a self-build. Consider the specs: authentic pre-war bracing, hot hide glue construction and a hand rubbed nitrocellulose finish. These are the features reserved for Martin’s most prestigious and expensive models.
Factor in a shaded top, your choice of tuners, binding, rosette, and a custom neck profile, and it’s a pretty attractive feature set. Clearly the finished result will depend on your skill level, but you can always contract out any parts that you feel are beyond your abilities – I did at several points in the build.
Finally, the important bit – how does it sound? It’s not for me to say but check out the some thoughts from the editor here:
This webpage features detail images of the finished build taken in our photo studio – we’re sure you’ll agree that Huw has done a fantastic job. The first thing that’s striking when you pick it up and play it is how ‘old’ this guitar sounds – there’s a palpable dustbowl, Depression-era flavour to the wonderfully dry-yet-sweet tones on offer.
The kit may hail from Nazareth but sonically, it has more in common with Gibson and Kalamazoo guitars of 1930s than it does with what you might think of as a classic Martin tonality. Capo’d up on fret four or seven, there’s a beautiful sweetness for fingerpicking that rewards a dynamic approach and it even has an almost mandolin-like woodiness when strummed.
It handles deep open tunings admirably, too. Americana in a box? I’d say so. Keep an eye on our YouTube channel as we’ll be posting a video soon.The post DIY Workshop: Martin Guitar Kit – Part 8 appeared first on The Guitar Magazine.