Wednesday, November 4, 2015

Making some Supro-inspired guitar bridges.

A local musician for whom I've done a lot of work had an interesting little project for me this week.  He picked up a Music Man Armada. We both agree it's nicely made, but he plays slide and found the string spacing a little challenging.
The high e is about 3/32" from the edge of the fretboard, and his slide bumps against it.
The spacing at the saddle needs to be adjusted. I can push it over by about 1.5mm and still keep the string over the polepiece of bridge pickup. We decided to file down the saddles and re-slot this bridge, but he asked if I'd be interested in making some non-adjustable rosewood replacements in the style of old 50's Supro and Airline guitars, one with a bone saddle, the other plain.
I took measurements from the stock bridge. Notice that the saddles aren't widely dispersed - this guitar has a compensated nut and so this bridge, though it might look "wrong", intonates very well.
 I planed up a stick of rosewood.
 And made up a quick cardboard template to mark spacing for the post holes and other measurements.

Drilling the post holes.
The Armada has a 12" fretboard radius.  I used my sanding block to mark the curve on one of the blanks.
A little self-adhesive sandpaper and a minute of scrubbing roughed in the shape.
I marked the staggered saddle arrangement in pencil
The post holes provide a convenient way to affix the blank for carving.
I tried to leave a crisp knife-cut surface. The zig-zag effect isn't as dramatic as on some original bridges, but the intonation requirements play a part in the design.
For the second bridge, I needed to angled slots for the bone saddle inserts.  Here's a useful trick.  I applied masking tape to the side of the bridge, and to the edge of a piece of plywood. By applying superglue to the tape surfaces, I get a very strong bond, but when it's time to separate the two, they come apart easily and cleanly by sliding a pallet knife between them.
I mark a line that coincides with the distance between my 1/8" router bit and the edge of the router baseplate, parallel with the intended slot. I screw down a temporary fence, complete the routing, then repeat for the other slot.
Strips of masking tape give me clear boundaries.  It's much easier than squinting at a pencil line.
 A triumvirate of terror! They add a definite warmth to the guitar's voice. They look pretty cool, too.

Wednesday, September 23, 2015

Floyd Rose Retrofit.

Recently I was asked to do some work on an Ibanez RG series guitar.  The owner wanted to add some pizzazz with new gold hardware and replacement of the factory-installed Edge series tremolo with an upgraded authentic Floyd unit.  He'd ordered the parts and realized that some extra fitting would be necessary.
The string locking screws protrude a bit farther on this model.
To make a custom-sized routing template, I first took a block of 3/4" (19mm) pine and planed it so that it fit snugly within the cavity.
Using pocket-hole screws I quickly added a couple of side wings to the block, producing a platform with an opening exactly equal to the width of the cavity. As an aside, you can see damage to the finish along the back edge of the cavity caused by efforts to prop the bridge up during string-changes. I usually suggest changing each string individually, or using a block padded with cork to prevent this.
My high-tech method for keeping the template in place involves lots of low-tack masking tape against the body, to which I can press down my incredibly strong double-sided tape. This keeps things very secure but I don't have to worry about leaving residue or pulling up the finish on older, more fragile instruments.
1/2" (13mm) flush-trim bit, lots of shallow passes. Don't try to hog off too much material. Cover the pickups because this is a messy process.  I added a couple of clamps to hold the jig in place, but only for peace of mind. They've only been tightened lightly, and the body is resting on a heavily padded surface. It's possible to dent the lacquer on some instruments with too much clamping pressure.
There. Clean as a whistle. The original rout for the pocket is actually tapered and quite irregular. As it happened, the mounting holes for the bridge studs were a little off-center too. Ibanez leaves a little bit of room to fudge the bridge position, and that's easy to do with the Edge series, as it has a flat blade rather than a radiused bearing surface as found in the original Floyd Rose.  It's a good idea to feather the razor-sharp edges of the fresh-routed pocket with fine sandpaper to prevent future chipping. I darkened the wood up with a coat of stain and it looked nice.
The aftermarket nut he'd purchased was high, and playing was stiff. I reckoned the nut would need to come down about .020" (.5mm) The landing surface was tilted a little, and I had visions of the binding delaminating and other horrors.  I decided to take material off the bottom of the nut instead.
I measured distances from the bottom of the string grooves to keep track of progress.
The nut casting is really quite rough. A couple of passes with the file revealed that the perimeter of the screw holes was a high spot. I took it to my rotary sharpening platter and used a course disc to gradually work my way down until I reached the correct depth.  It's not a job to rush, and you have to measure constantly.
Much better. It's flat, to the correct dimensions, and ready to install!

Friday, July 10, 2015

I'm currently working on another 5-course mandolin, this time in a somewhat modified F-style.  (The little swoopty-pointy-thing in the lower bout is cute but I thought I'd save myself a few hours.

Thursday, May 14, 2015

Installing a K&K Sound Aloha Twin Ukulele Pickup.

I've seen more than the usual number of ukuleles this month. Nice ones, too.  A gentleman contacted me about amplifying his Martin tenor (all koa - a gorgeous instrument). He'd purchased a soundboard transducer from K&K, which I've installed before.  Working within the close confines of a mid-size uke presents a step up in the complexity department.  The soundholes are too small to allow your whole hand inside, and the scale length is just a little too long to allow one to reach the desired location using fingertips. Well, it's possible to reach, but precise placement requires luck.

There are two options for installation - thin double-stick adhesive can be used, or superglue, which provides better clarity and tone transfer.  The owner was looking for nice clear articulation, and as this was to be his stage instrument he like the idea of rock-solid attachment.

The transducers (there are two of them) need a clean, flat bridge plate.  I used a small sanding block. (This is really important in older instruments where oxidation and atmospheric oils can prevent proper adhesion, or in guitars with rosewood bridge plates.
After sanding it's important to clean the surface. A towel lightly dampened with alcohol does the trick.
Precision in placement makes a difference!  With the glue method you only get one shot, and in the heat of the moment, working upside-down in a mirror it's easy to lose one's bearings.  I like to give myself some guidance marks. A set of clamping hemostats and the stub of a pencil suffice.
This way I can measure and place the transducer dots between the 1st and 2nd,  and the 3rd and 4th strings for optimum balance and volume. Right under the saddle is the place to be.
I choose to install the jack first, as there's enough play in the wires for me to access the dots through the soundhole.  The jack hole is drilled undersize, and a tapered reamer is used to sneak up on the proper diameter. Drills tend to chip out the lacquer, or in really bad cases they can tear out pieces of the side wood. I use a little right-angle probe with masking tape on it to mark the thickness of the end block. I can then set the internal nut and washer for the jack at the correct depth and not have to keep test-fitting it until the proper amount of thread is exposed.

This is the end of a standard 1/4" (6mm) jack glued to a length or thin bamboo dowel. I plug in the jack and fish it through the endpin hole.  This is helpful in full-sized guitars, absolutely essential for instruments you can't fit your hand inside. (Electrics with f-holes, etc.)
Here's the real trick. A piece of 1/4" (6mm) by 1/2" (12mm) aluminum bar bent into a funny shape that lets me provide adequate pressure against the bridge pad.
The Aloha has a little lip where the lead wire contacts the disc.  I made a cork pad with a recess to accept the wire. The dot is held in place with a little bit of double-stick tape. This releases easily after the glue has cured.
A couple of deep breaths to focus the mind and steel the nerves.  I like to use very fresh medium viscosity super-glue.  The gel works too, but it's slow to set and you have to hold it in place for a long time.   There we have it. Nicely positioned and firmly attached!  I like this pickup. It's got a whole lot of output and sounds great, even without a preamp.

Saturday, April 25, 2015

 Closing the box on a red cedar / East Indian rosewood guitar.
Five fans and a deeply angled diagonal transverse bar are elements picked up from the design of Miguel Rodriguez Jr.

Wednesday, April 1, 2015

A Morin Khuur repair.

I receive a large number of comments and emails regarding a Mongolian instrument I built some years back and profiled on this blog.  At the time, I had only a few photos to work from and extrapolated things like string length and box dimensions by scaling up details from the pictures.

Recently I was contacted by the owner of a bona-fide genuine Mongolian-made fiddle. She has had difficulty keeping it in tune from the beginning and wondered if there was something I could suggest. We discussed options and I came upon a plan to retrofit it with mechanical tuning machines.

To start with, for a student-grade instrument it has some beautiful carving.  The tapered pegs it was fitted with didn't seem to correspond to the usual 1:30 found on violas, or the 1:25 commonly found on cellos.

The multistranded nature of morin khuur strings necessitates a large diameter peg. Unfortunately the materials used here weren't up to the task. The pegbox seems to be made from a fruitwood, and the pegs themselves *might* be an Asian variety of soft maple.

The wood is just too soft and fibrous. Assuming I had a peg shaver large enough to deal with these, I'm confident they would quickly deform.  No amount of peg compound is going to help this situation!

The cheeks of the peg box were too narrow to accommodate the electric bass tuners I had in mind so I made up a couple of little risers.

The shafts fit nicely into the vacant peg holes.  I scribed around them...
And scraped back to bare wood for gluing purposes.  Note the knot with bark inclusion! 
A coat of colored varnish makes the risers less visually obtrusive.  You can see manner in which the strings are held in place through the lower peg hole.  I made a slip knot and cinched the string through the split shaft. It was a tight fit working in the confines of the pegbox but it didn't take long.  Those thinking of trying this for themselves might graft a smaller diameter cord to the end of their strings to make the job less fiddlesome.

The owner expressed some remorse about having to lose the traditional appearance because the pegs are stylized ears, after all.  I reasoned that by fitting the pegs into the exit holes, which are considerably smaller  I could mark where they fit snugly, amputate, and then graft the resultant nub back onto the shaft. Some glue and a screw hold them together.
It worked well!  As do the machine heads.  Tuning is now a breeze.

It's a handsome instrument. The box is made entirely of cedar.  I'm not exactly sure how the arching was accomplished, as it's all in one plane around the perimeter.