February 24, 2010 - ModGuitar Senior Editor
Gibson 'EBO' Bass To 'SG' Guitar Conversion
EBO Bass To SG Style Guitar Conversion Project
Hidden away in the workshop we found a semi-vintage Gibson EBO bass. The headstock couldn’t seem to keep from snapping off. It had been repaired a few times already and was missing some parts and crucial components like the pick-up. It also just happened to not play or sound very good. Vintage SGs fetch high prices, and this SG body was still intact…so The SG BASS-GUITAR MOD is born.
It was a long and fairly involved mod involving removing the bass neck, reconfiguring the body to work as a guitar, building a new custom neck and then doing some finish matching to pull it all together.
We’re proud to say, this project was a huge success and our studio is now the proud owner of an almost vintage, almost Gibson, one of a kind SG.
To determine if this project was worthwhile we spent some time laying out components and taking measurements. From our initial assessment we determined that a stop tail could be retrofitted to mount where the bass bridge had once gone. With a new tune-o-matic style bridge being added along with a pair of hum-buckers and the new neck.
Getting The Body Ready For A New Neck
Removing the old neck seemed simple enough. We were extra careful when removing material to avoid cracks or chips to the wood that was left. A hacksaw made quick work of the remainder of the bass neck, cutting through both the aged mahogany and the truss rod easily enough. Hated to do it, but the end result will prove to be worth the sacrifice. What was left of the original neck was then chiseled out of the tenon joint in the body. After that we carefully set up a router template to cleanly cut a pocket for a new neck. This was tricky, as the template needed to be angled slightly so that the new neck would tip back from the face of the guitar so that the strings would align with the top of the new bridge while still leaving room for fine tuning the string height. Too much or too little angle and the strings would ride high or low and no amount of adjustment would be able to correct it.
We turned down the original mounting screws that had held the bass bridge in place. They had gouged and jagged edges which would be uncomfortable to have your hand near while playing. With a drill press and a file, we were able to quickly round them over and then a careful cut to the top with a hacksaw made them adjustable with a screw driver. Luckily, the original bushings and screw placement worked with our new stop tail.
Here you can see the neck where it joins the body and the stop-bar tailpeice mounted were the original bass bridge once was.
For the new bridge, 2 holes were drilled just large enough to allow the larger bushing style adjustment screws to be carefully threaded into the body without the bushings. A hybrid between old and new. Templates were used to align and then route a new cavity for a bridge hum-bucker. The rhythm hum-bucker cavity was already cut from when this body was a bass. Although the cavity was a bit larger than your standard hum-bucker opening. We decided to use another hybrid approach and use a hum-bucker mounting ring for the bridge pick-up and a custom pick-guard for the rhythm pick-up. For pick-ups and electronics a set of Elitist pick-ups were found on Ebay and the other components, (switch, potentiometers, tone caps, output jack, etc) were ordered online. We’ve been impressed with the elitist pick-ups in an actual Elitist guitar, so this was a luck find. We tried to get away with a budget switch, but found that the solder tabs snapped when they were bent even slightly. So for that component we recommend a higher quality part such as Switchcraft. The pots are Alpha quality pots from Stew Mac 500k for both tone & volumes with a standard .22pf tone caps. Nothing really fancy there. Most of the time these standard quality components are just fine for a build of this type. Once it’s established that a guitar is a keeper, modding it additionally with high grade electronic components becomes an option.
With the body prepped and ready, we turn to creating a new neck to turn this ‘once a bass’ into a guitar.
We ordered a maple neck blank, and a rosewood fingerboard, pre slotted in Gibson standard 24 3/4″ scale, along with a dual adjustable truss rod, a tall and narrow vintage profile fret wire, pearloid dot inlay pieces and a bone nut from StewartMcdonald.com. Total cost of parts was considerably less than what you will pay for a neck from any of the custom shops like Warmoth – though this is a very complex build project which takes a bit of time and experience to complete satisfactorily. So the cost/vrs end result becomes a factor in how you might decide to go about a project like this yourself.
From here on out we are designing, fabricating and assembling a custom neck. Which, aside from carving your own top on a solid body, is one of the most difficult projects to do on a solid body.
The fingerboard comes with a few extra slots, in case you want to make a 24 fret neck. We didn’t, so those are trimmed off using the band saw, cutting right down the 23rd fret slot. And then a touch-up of the edge with a file and sandpaper, leaving some material for a final fit. The fret board comes slotted and radiused, but is not tapered.
Left: The placement of the stop-tail, bridge and pick-up laid out. Right: Trimming the pre-slotted fingerboard.
Our maple neck blank is a standard plain hard maple plank long enough to get both the neck and headstock out of the single piece. We carefully traced out the fret board centered and at one end of our neck blank. From there we determined where our truss rod channel would need to be routed, the taper of the neck (matched to a favorite gibson neck in our collection), and where the headstock begins and ends.