Walnut Scroll 4-banger - Cm#1

[erikbojerik]

OK, this is a scroll 4-banger for Chris from Virginia. Les Claypool was a huge influence early on for Chris, so this one has some signature influence. It has a couple of cool unique features that I'll highlight as you see the build progress, and how I go about making them happen.

Walnut body w/ flame maple stringers

EMG 35DC with wenge pickup surround & wenge control plate

Hipshot A 0.750" brass (black)

bolt-on 3-pc laminated rock maple neck, CF rods

wenge headstock overlay & backstrap

quartersawn wenge fingerboard, 24+ frets, zero fret

double-action truss rod w/ access underneath end of fingerboard

Hipshot ultralights (black)

Tru Oil finish

Straplocs (black)

Chris wants a pretty low string profile above the body, so it will end up as a bit of a carve-top thinning slightly toward the body edge. I like this solution better than routing a recess for just the bridge.

Wood selection is probably one of the most important steps right off the bat. We didn't want to go crazy with any figured walnut on this one, so I found a nice dark flatsawn piece with some interesting grain.

For the laminated neck I like to find flat-sawn 4/4 stock, cut the lams, then flip them 90° to yield quartered lams. So the lams will come from the left side of the maple piece.

The last bit on the right is some perfectly quartered wenge (view is of the flat-sawn edge).

After rough-sawing, the neck lams are first planed flat on one quartered face using a power jointer, then squared on one flat-sawn face using the same. This yields a perfect 90° angle whose sides yield a flat register for the thickness sander.

After truing up in the 16-32 they're ready for gluing in my glue press, which amounts to a pair of 2" aluminum angles clamped shut with 8 screw-type bar clamps. Here's a shot of it with a different neck in the press. The clamps are the ends keep all the lams clamped down to a flat piece of MDF underneath the press (can't see it from this shot), so that the lams don't float around while squeezing the angles shut.

IMO it's really important to have the lams flat and true (all 90° angles) at this stage.

[erikbojerik]

Body lams are first thickness planed, then jointed true on the glue edges. Then the whole works is clamped together using big 36" Jet bar clamps.

The body blank is skimmed down to thickness and ready for routing the neck pocket (after I get the body and neck templates done...hehehe ).

[erikbojerik]

Here's how I'm doing my straight fingerboard radius these days. First the nicely quartered wenge FB blank is thickness sanded a hair on the thick side of final spec...talking 0.01 or so. Then it is double-stick taped to the trusty (but straight and true) length of black limba (not neck-worthy due to a well-placed knot..).

Now rotate 90° and walk it over to the router table...

...where there's a fence set up flush on the bearing of the oh-so-special router bit...the 10" radius bit!!

[erikbojerik]

After routing the radius, there's a little touch-up needed in the center of the board as a tiny ridge remains.

Now for the key step of the Integral Binding...this is basically cutting off the edges of the fretboard on a taper underneath the outermost strings, and saving these offcuts for binding the edges of the fretboard. This allows the grain to match across the seam.

First, cutting off the edges:

Cutting the slots on a radial arm saw with a 34" StewMac template;

I have the 1/16" pin inserted into the back-side of the fence, so when I want to slot, I change the blade, flip the fence, and slot away.

[erikbojerik]

But that gets us only 24 slots, and we need 28. So I bust out the calipers and fret locator spreadsheet, draw them on the board, and flip the fence back around so that it doesn't interfere with the square-ness of the cut.

Now we're ready to glue the binding back on;

A little Titebond, a few clamps (seven...), and we're good to go;

I wait about 15-20 minutes, then go in with a fret slot cleaning tool to pull out the glue squeeze-out that inevitably runs into the slots. This is quite a bit of extra work in board prep and nipping fret tangs, but I really like the lack of fret ends along the edges of the neck when done this way, it eliminates the effect of those ends sticking out due to seasonal (winter) shrinking of the neck wood during times of low humidity.

Here's a shot after sanding touch-up to remove the glue smear:

[erikbojerik]

OK, the neck. This is one interesting neck...we will try to have access to the truss rod adjustment nut underneath a cover at the heel end of the neck. The cover will be a 4-fret extention of the fingerboard (replete with frets!) held on by neo mags....that's why we needed 28 slots in the fingerboard!

The trick here is to not remove too much material from the neck heel....this being a bolt-on, we want to leave as much material as possible for good stability and coupling to the body. For this reason, I'm flipping the truss rod upside-down so that the adjustment nut sits directly under the fretboard (top of the channel) rather than at the bottom of the channel as usual; this requires a stepped channel (to avoid removing excess wood from under the adjustment nut). This also means the truss rod works in reverse (i.e. CW turn of the nut LOOSENS the rod, does not tighten the rod).

We first rout the channels for the CF bars on the router table; just run the squared neck blank against the fence and rout blind, making small adjustments to the height of the bit until the desired depth is reached. Since the CF channels are symmetric about the centerline, all I have to do is flip the blank and rout the other one.

First I check the depth, using the end of the digital calipers, and rout in 2 passes:

The CF bars I got from LMI were a little wider than 0.25" so I trued them on the thickness sander, and installed them with 60 minute epoxy.

[carousel182]

looks nice man! im jealous though, where did you get a 10" radius router bit?

[erikbojerik]

OK, busted out the trusty 4-string MDF neck template, marked the locations of the nut & frets 12, 24 and 28, lined 'em up on the neck blank and traced the outline on the blank. Ditto for the fretboard.

I then made up a mock neck heel from scrap pine and shaped the end and traced it onto the neck blank.

I then used the mock heel to fabricate a plywood template for the neck pocket...my regular 4-banger template is for a 22-fret bass, so I needed to make a new one for the 28-fret wonder. Once it is done, this template will be fixed to the body and the neck pocket will be routed before anything else is done on the body blank.

[erikbojerik]

looks nice man! im jealous though, where did you get a 10" radius router bit?

Custom order. A steal at $200.

[carousel182]

haha wow, I guess I'll stick with my jig

[erikbojerik]

...after radiusing, I got a coat of epoxy on the fretboard. System 3 mirror coat, just applied with a gloved finger being careful to not get too much down in the fret slots. The little bit that does is easily cleaned out with the fret slot cleaning tool.

Mmmm....chocolatey wenge happiness! :

This is just pore filling, so a thin layer worked into the grain. Once this cures, I'll sand it back and see if we need another coat.

[erikbojerik]

Managed to sand down the epoxy, it did a nice job of filling the large pores and left enough of the small pores open to give it that nice woody look. I cut a rough taper ~3/16" outside the final taper, then straightened it out on the jointer; after that, there was still a good 1/8" left outside the final taper.

[erikbojerik]

Chris has been a champ this whole build, working on gathering together all the parts. But Hipshot has been a bit of a stick in the mud about getting him the ultralight tuners (I hope they come with the tiny screws for the back Chris!!). I was hesitant to cut the scarf before having the tuners in hand, but just yesterday I found the drawings for them that gave me the dimensions I was looking for, namely the post height.

With that in hand, I could CAD out the scarf angle needed to get a good break angle over the nut for the headstock Chris chose...14° does it. So here's how I go about doing the scarf.

I actually cut it a bit upstream of the nut location (which is just over the ends of the CF rods), so that instead of being underneath the fretboard, the scarf joint itself is within the headstock. When I glue on ears and laminates front & back (all of which are required for strength), the thing will be bomber and the joint will only be visible at the ends of the headstock.

Step #1: draw the angle in with a protractor. Here I've drawn an arrow to indicate the original "up" direction of the end-piece.

Then the end gets cut off on the bandsaw, cutting right on the line.

Then the short piece is flipped over, and will eventually be glued to the underside of the headstock like so:

The line of the cut was purposefully drawn 1/4" or so upstream of the nut, so that after I glue on the scarf, I can plane flat the headstock surface without intruding on where the fretboard and nut will be glued down.

[erikbojerik]

Of course the bandsaw cut is never perfect and square, so this requires a little work on the jointer to get it flat.

The jointer is set so that it barely shaves off any wood, and the faster it is drawn across the blade, the flatter is the result.

The short piece is too small to plane down on the jointer safely, so it is trued up by sanding the cut face down on a flat board.

[erikbojerik]

With the pieces lined up so that the headstock face is flat, the headstock length is too short (6") and too thick. But I can easily extend the short piece out to increase the length of the headstock to 7+" (I need only 6-3/4").

But now the headstock face is not flat, I need to thin down the short piece on the drum sander. I first make a pencil mark on the short piece that I will plane down to:

The short piece is stuck to a flat board with double-stick tape:

And the whole works is run through the 16-32:

[erikbojerik]

With the short piece sanded down to the line...

...it is now at just the right geometry so that the headstock is more than long enough, and more than thick enough, to leave some room for final shaping and thicknessing....

...but the glue-up won't happen until after I've cut & routed the taper, and approached the final neck thickness.

[erikbojerik]

I managed to rout the final taper on the fretboard and neck. The fretboard is stuck to the taper template and routed flush with a template following bit on the router table.

The rough taper on the neck is done on the bandsaw (staying 1/16" outside the line)...

...then the neck is stuck to the same template and routed flush just like the fretboard...except note that the fence has been moved back to allow for the headstock.

It's really starting to look like a neck!

[erikbojerik]

Also finalized the neck heel outline and neck pocket template, iterating between the two with gentle sanding.

Now with the neck heel & template finished, time to thin the back of the neck to final thickess at #15 (0.64" without the fretboard). This was done on the 16-32 with judicious use of the height crank and table feed, working down to thickness between the headstock and heel (pencil marks on the side of the neck tell me the boundaries to keep the drum between).

Precise and level result...the thickness will taper down by 0.12" under the nut, and head & heel transitions sanded, after roughing out the back contour.

[erikbojerik]

Time to rout the neck pocket! The template is stuck down on the body and routed out...normally I would have removed most of the meat with a forstner bit on a drill press, but since the drill press is at work...nah!

Nice & clean!

If you squint, you can see a bass in there!

[erikbojerik]

Bandsaw the Body Time.

A 14" Delta I have at work, with a 1/4" blade. Helps me keep the 3/4" resaw blade on the big mutha I have at home.

I've purposely left some meat around the arse, it will get shaped once I have the bridge and know for absolute certain where it will go. Lots of meat on the neck pocket, this will be a sculpted 4-bolt pocket.

Still a lot of meat around the scroll as well of course.

[erikbojerik]

I managed to rough out the back contour. First was a trip through the overhead router (=duplicarver with the stylus pinned) to put a 7/8" roundover on the back of the neck. Here the neck is double-taped to the neck taper template, which the bearing on the roundover bit follows.

Then it was time to bust out with the angle grinder to knock the shoulders down a bit, and thin slightly the neck as it runs toward the headstock. This whole time I'm keeping the neck on the template, it serves as a good "handle" and helps keep the fretboard surface flat while I shape the neck.

Here's a closeup of the neck back with one side knocked down; the centerline is at 0.62" thickness...NOT to be touched with the grinder. Same goes for the sides of the neck, this grinder removes a lot of stuff quickly so it really pays to be careful here. Total 20 minutes into it.

[erikbojerik]

Once the other shoulder is knocked down, time for the ROS with 50-grit paper to smooth out the 36-grit angle grinder marks. At this point I use only the ROS for approaching the final neck thickness (0.52" at the nut, 0.62" at #18) as it give me more control over things at this point...constantly checking with the digital calipers. Slow yeah, but accurate.

Chris wants a flat-C on this neck, so I'm leaving a little bit of shoulder on the neck for now until he has a chance to play it in the white and give me some feedback on the neck contour....should happen sometime in the next few weeks (if the tuners ever come that is...).

Enough time left this evening for gluing up the headstock scarf Setch-style. I use tape.

And Titebond of course. Tape goes on the face-side of the headstock and glue is applied to the side of the joint that faces the back of the headstock. Then our little sawn-off piece is flipped and glued to the underside of the headstock.

Like so:

The piece is slid into place so that the face of the headstock is as flat as can be, then the tape is smoothed over. A little squeeze-out cleanup, then another layer of tape covers the joint on the underside of the headstock.

[erikbojerik]

Not just Titebond and tape....clamps too.

The "trigger" bar clamp serves to squeeze the tape onto the neck so that it doesn't slip, then two screw-down bar clamps squeeze the side of the joint closest to the nut. This starts to close the joint down, but also adds pressure to the tape to keep it on the headstock...no slippitude.

Then two more clamps to close the other side of the joint and keep the tape there from slipping. The wedge-shape of the scarf joint wants to slip when clamped like this, but by covering the joint on both sides with tape and strategic clamping, the clamped tape keeps it all in place and you can crank down on the clamps as much as you like. Clean up the last of the squeeze-out and let set for a day.

Down the road I will thin the headstock and ears will be glued onto the sides, as well as front and back wenge lams...so the scarf joint will be entirely hidden within the headstock, only to be (barely) revealed when I carve out around the nut, and at the endgrain of the headstock.

Thanks to Setch for showing me this! I have never liked the look of a scarf joint underneath the fretboard, and I would have never done one because of that...until I learned this way of doing it.

[erikbojerik]

he Saga of the Revolving Door of Tuners is still ongoing, but in the meantime it is full steam ahead!

Got the ears glued on and planed down, and sanded an angle into the edge of the wenge headstock overlay using the tilting table on the edge sander....this is the edge that will butt up against the "nut".

Clamps and an MDF caul, epoxied on.

Quartersawn headstock lam to match the fretboard.

[erikbojerik]

The matching wenge backstrap is spritzed with water, wrapped in a wet paper towel, sealed with aluminium foil, and clamped to the underside of the headstock with a pair of small silicone heating pads on the outside. The heat is cranked up and the backstrap is steam-bent into the shape of the backside of the headstock, overlapping slightly onto the neck shaft.

For headstocks I always make a plexi template from a paper template printed out from CAD. The plexi lets me line up the centerline, trace out the shape, and register the pilot holes for the tuner holes.

Headstock is bandsawed close to the line, then sanded on the spindle sander right to the line.

A little rasping & sanding, and the backstrap is roughed out. Front and back of the headstock will get an epoxy grain fill before finishing.