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Project: 80s Aria Pro II RSB retrofit "Black n' Gold" neck


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EDIT: I see a lot of traffic coming into this thread because of the subject material, so it's best to qualify what this project was and wasn't for various reasons. Firstly, the headstock shape was out and has been revised for subsequent Aria Pro II SB type projects. Mostly this was from not working off a physical example, so I'd like to capture that thought. Secondly, this whole thing was massively screwed up by the painter not following instructions on what to do, pretty much writing the whole thing off. In general the process steps are valid, even though they've evolved greatly over the intervening years!

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A friend of mine sent me an Aria Pro II RSB-600 bass a while back which he wanted retrofitting with hybridised SB-1000 electronics. Because of the extensive work that bass would require to do it proper justice (including a full refinish) we decided instead that I would trade the bass for work. That work being on a different bass acquired in Japan.

The project remit is a new neck to replace the one that is missing, but in the style of the 2+2 SB Black n' Gold basses rather than the 4-in-line style of the original. Additional modifications include a brass nut, body end truss rod access, gold fretwire and neck profile specs identical to that of the '84 APII SB-R60. The body has all-original hardware and electronics so this is purely a neck retrofit. Despite the original neck being Maple (listed in the catalogues as "replaceable Maple"!) I am nudging my friend in the direction of a Maple/Wengé laminated neck.

Reference photos of other RSB Deluxe-I's:

Catalogue photo (centre model). The colour of the actual model is identical to that on the left.

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Original headstock detail.

aria-guitars-pro-ii-rsb-deluxe-5-129080_

Body detail.

Aria_Pro_II_RSB_Deluxe-I_02_zpsfb8708f4.

Headstock transition.

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Actual photos of the bass:

Six-piece Alder body!

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I might consider swapping that gold baseplate out for a black one to properly continue the Black n' Gold theme.

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The neck plate (not pictured, duh) dates the bass to 1984. One of the best time to be buying guitars from Japan!

IMG_5538_zpsda845214.jpg

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I'm brainfarting my working methods as I go - partially as documentation but also to give an idea of how I approach this work.

String to string spacing at bridge - 18mm (54mm string spread).

Minimum intonation point to rear of neck pocket - 230mm.

Neck pocket width - 63,5mm (62,0mm) to ~60mm at open end.

Neck pocket depth - 19mm at rear including 1,5° neck angle slope.

Neck pocket length - 110mm.

Heel thickness at screw locations - 24,5 - 25,0mm.

Base of neck pocket to bass of rod adjustment recess - 8,0mm.

Practical saddle height adjustment above body plane - 13mm to 19mm.

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Let's start out by transferring this information into CAD. I opened my SB-1000/SB-R60 plans and deleted the SB-1000 specific stuff and all the things that do not apply here. So this is roughly what we're aiming towards. Currently this drawing still represents a neck-through instrument with unchecked geometry.

Image1_zpsbd51485b.jpg

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Okay cool. Lets move the neck out of the way since we need to sort out the body first....

Image2_zps0ffe8288.jpg

The bridge location and pickup are moved. Neck pocket bounds added. A bit of appropriate CAD work music is put on also. Wes should like this since it involves very Slayer-style soloing plus headbanging cheerleaders with assault rifles and handguns.

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The body outline is perfectly in line with the rest of the SB models so we're working within sub-mm tolerances here. A word of wisdom here is to have a roll of masking tape handy when taking measurements involving combinations of metal rules, calipers and protractors. Now is not the time to add more dings and scratches to the workpiece!

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Despite being an imperfect method in terms of tolerances and potential for geometric distortion, the following method is fine for the purposes of this type of project since true measurements are being acquired directly from the workpiece otherwise.

Photograph of the neck pocket added in as a background image, requiring scaling and alignment.

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Apparent length of the neck pocket according to the photograph:

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....actual length of the neck pocket as measured....

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110mm / 223,4mm = scaling factor of 0,492

viola.gif

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This highlights the minor differences in neck/heel transition between the neck-through and bolt-on versions of the SB, plus the error margin that scanned or photographed images can introduce to measurements!

For these purposes these differences are irrelevant. Nothing is being scaled off the image.

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A bit of cleanup. All that is important here is the neck pocket geometry. The shape of the neck pocket end is purely for reference purposes. A little bit of discrepancy exists, but is inconsequential since I am not building a body here.

Image10_zpsda106848.jpg

My generic fret scale is imported. In addition to the fret locations, the nut break point and absolute scale endpoint are included. As an object this is then scaled to the 860mm scale length of the bass.

Image11_zps1b2ebadf.jpg

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Specification for the nut width is 40mm. Two guides added either side of the centreline at the nut breakpoint.

Image15_zpsb974b4a5.jpg

Taking into account finish thickness, an offset is added to the rear of the neck pocket....

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....and a neck profile line drawn coinciding with these two points:

Image17_zps2ad3067c.jpg

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Headstock outline added.

Image20_zpsd19aeb93.jpg

The actual angle of the headstock will be a nice 13° and would be subject to distortion in a top-down view.

Image21_zpse363ea98.jpg

At a small angle of 13° the apparent length of the headstock is just shy of 5% out. A significant tolerance if you are tracing from photos, and definitely too large for any kind of reliable measurement derivation.

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The recessing of this type of bridge in many Aria Pro II basses (and probably the guitars) was inconsistent resulting in variable ranges of intonation. The neck for this bass will be made according to the geometry of the body in order to sit in the "sweet spot".

Bridge placement according to observed minimum/maximum saddle height adjustment:

Image23_zps6d334036.jpg

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Let's take a quick break from CAD to do some maths on the nut spacing. I prefer equal spacing between the strings, so here's an Excel spreadsheet I threw together to calculate these for both 4 and 5-string basses:

Image11_zps1b2ebadf.jpg

This should illustrate how this simple sheet works:

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Generally I will use the values of the string set I am designing the bass for (in mm) with 3mm either side of the nut. This leaves me with 8.88mm between the strings for my desired string set. Drawing the nut in CAD:

Image30_zpsbeae3aa2.jpg

...then adding string paths with line weights representing string gauges...

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...leaves the strings 5,58mm and 6,08mm from the edge of the fretboard at the body end, bass and treble sides respectively. Perfect.

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Planning out the headstock scarfing and stock requirement.

Image32_zpsc5a63635.jpg

The nominal neck blank size works out to 840mm x 62mm off 20mm stock. Given that there will always be losses from planing and general shaping my blank size will be at least 850mm x 65mm x 25mm.

Breaking this down into a five-piece laminate at more or less round figures, three pieces of Maple at 25mm square and two strips of Wengé at 5mm x 25mm will allow me to taper the central Maple laminate from 23mm to 8mm.

Image33_zpsd90991f2.jpg

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  • 4 weeks later...
  • 5 months later...
This is where the neck is currently at.
Scarf joint cut and cleaned up with seperate piece for the headstock itself. Crosses indicate locations outside of the neck which will be drilled for screwing the two pieces together to align during glueup.

The neck component was drilled with 6mm holes so that the screw threads wouldn't bite, thereby cinching the two pieces together as the thread bites into the headstock component. The two pieces were dry fit, taped together temporarily and the screws tapped lightly to make locating marks. The headstock was pre-drilled with 2mm holes to prevent any splitting. The screws prevent any slippage during glueup. Four clamps were used in the corners and one in the centre.
Finished item, perfectly aligned:

The excess headstock waste was cut on the bandsaw and the neck's gluing face trued up manually. I don't trust jointers not to try tearing out grain at this stage.
Mark up the face with a pencil:

Sand like Popeye.

Check for progress, re-mark, wash and repeat.

Bang! And the dirt is gone.

Measurements, centreline and everything else re-checked and re-drawn.

The end of the neck was shaped to fit within the neck pocket. Checking the fingerboard for alignment.

Measurement check from the 12th fret to the minimum saddle adjustment range. This is an 860mm scale so the 430mm measurement is nailed. Totally nailed.
The fingerboard was glued up and the neck shaped on the table router. Like the original Deluxe-I neck, the end of the fingerboard was rounded after the 22nd fret unlike the neck-through SBs which had a squared end and 24 frets.
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  • 2 weeks later...

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