Epiphone Explorer Guitar Repair Project
Around 2012 I bought a second hand Epiphone Explorer off Ebay for 60 Euros.
It was a circa 1980s instrument with EMG81 active pickups and an early version (and nasty!) Floyd Rose licensed tremolo. It was a bit bashed up. The head stock had been burnt on the last 4 cms, which had resulted in melting the paint/plastic coating. But hey, it was only a 60 Euro guitar for messing around with, so no worries!
I 'pimped' it up with chrome pick up surrounds, set up the intonation, cleaned it, polished it and not much else. The neck played well, however the Floyd Rose (licensed) tremolo was awful! It had the stock fault of all cheap tremolos. The metal is soft and so over time the knife edge either goes blunt or scrapes away the posts, both of which mean that the bridge does not return to pitch.
So I blocked the tremolo, through the audacious placement of some large nuts (M11 or M12) either side of the cast block, which locked it solid. This meant the guitar played well enough and this was how it stayed for a few years. The sound wasn't brilliant but given the body was plywood, and the cheapness of the components, only to be expected.
I subsquently gave the guitar to my son, as a first guitar, for him to learn on. He used it for a year or so then one day 'phoned to say that something had gone wrong with it. On seeing the guitar it was clear that the Floyd Rose licensed bridge had completely disintegrated! The die-cast block was in about 4 pieces - catastrophic failure!
I told my son I would repair it for him, as he liked the guitar - he plays Metal and it is his kind of instrument. However intensive investigation revealed a major problem. The original Floyd Rose (licensed) bridge was of different dimensions to all current Floyd Rose bridges. In fact no tremolo bridge currently on the market would fit as a 'drop-in' replacement.
As he wasn't bothered about a tremolo (it had been locked anyway, remember?!) I widened my search to fixed bridges. Sadly, I was still out of luck. There was no fixed bridge that would fit, either the post holes were a problem or the through holes in the guitar body were in the wrong place. Bummer!
The only option was to fill in the holes with new wood and then re-drill. As I had little prior experience with this kind of woodwork, I went to see a friend who is a cabinet maker.
As luck would have it he had some off-cuts of maple (which is a good tone wood) that he was willing to give me. He also had some industrial strength wood glue that he said we could use to fix them in place. In exchange I spent three afternoons up to my ears in mud, helping him dig out an old well - but that is another story!
As I was hopeful that significant blocks of maple might help improve the tone, I decided to use a router to remove quite a large block of the guitar body. I had also chosen to fit a Tune-o-matic two piece bridge, as it is what is fitted on Gibson Explorers, so it would look 'right'.
This picture shows the first marking out of the area to be removed on the front. It was 10 cm square.
This picture shows the plywood construction and you can see both the front tremolo bridge hole and the back spring cavity.
Here you can see the routing underway. I didn't use guides just followed the scribed lines and stayed a little inside, knowing that I was going to have to sand etc. later anyway.
I didn't protect the guitar surface as I had decided to do a complete re-spray anyway. I thought I might as well completely renovate the guitar for my son.
I just went down a few millimetres at a time, until I got to half the body depth.
Here is the finished top rout.
Here is the block of maple that will need to be fitted into the hole.
Here is the rear side. No routing necessary, I just had to shape the rear maple block to fit the hole. That is very easy to say, but the reality of getting the blocks to fit snugly, without taking too much wood off so that they became loose, was hard work. Sanding had to be done by hand with wood files and sand paper. With each block being checked, re-checked, re-re-checked, sanded again, checked, re-checked, sanded again etc. etc. Took a few hours to get both blocks right. This was further complicated by the fact that the front void and rear void had recesses as well as the through hole. I decided to make the bottom surface the datum, which meant that the rear block was just going to be flush to the base surface, but the top block had to have a projecting section about 3mm deeper than the base of the top recess in order to make flush contact with the rear block of maple. This was vital if the tonal properties of a solid block of wood were to be attained. This was tricky to get correct.
The maple blocks were too deep so I had to rout them down to the required depth.
Here is the rear block fitted to size.
Using some heavy duty clamps and a mastic-based professional wood adhesive, the blocks were glued and clamped overnight. The resulting bond was very good, with a tap on the inserted maple blocks giving a nice resonant sound. Now with the woodwork done, the re-painting commences. The first stage is rubbing down the old paintwork.
The scratches from routing were quite deep, so the front and back paint had to be stripped back to the wood. I used 100, 200 and then 400 grades progressively. The sides just had to be roughened to form a key for the undercoat with 400 grade.
The body rubbed down and ready to go.
You can see that the front maple block is slightly recessed. In my measuring and aligning, I had noticed that the string height (as set by the neck position) was pretty much on a critical limit of the lowest setting of the Tune-o-matic bridge. So I recessed the maple block by around 1.5 mm to try to give a little more 'headroom'.
I used some filler compound to fill in these recessed edges to give a rounder profile. I should also probably should have used grain filler at this point, to get an absolutely smooth surface over the whole of the exposed wood.
We now came to the really mission critical part, the drilling of the holes for the inserts for the bridge and tailpiece. These had to be very accurately drilled and perfectly vertical.
This online diagram shows the standard Gibson Explorer dimensions, although I didn't buy the full-size copy, this was sufficient to enable me to verify the layout, angles and dimensions.
I bought a 1 metre steel rule in order to measure really accurately and align the holes. This was complicated by the fact that Tune-o-matic bridges have a bridge that is set at scale length for the high E string end, but recessed a further 3 mm back for the low E string end. This is down to physics, thicker strings have more mass which alters their resonant distances. In reality frets are 'averaged' a truly accurate fretboard would have curly frets (i.e. google "True Temperament" necks). In order to be able to set intonation for the thickest and thinnest strings on a bridge that was parallel to the nut, a wide range of adjustment would be necessary. This would make the bridge wider and more costly. So they get around this by slanting back the thicker string end of the bridge. An Ingenious solution.
I measured the fretboard scale length (to determine this you measure the distance from the front of the nut to the 12th fret, then you double this length to get the scale length). I measured my 6 guitars and found that there were 4 different scale lengths amongst them! Something I had never noticed before. The Epiphone turned out to have the standard Gibson scale length of 628mm. I then marked the high E string end of the bridge for this length and added 3mm to the low E string end. The tailpiece is just set parallel to the nut.
This Gotoh data sheet shows how the bridge elements are aligned.
Jumping ahead of ourselves, the requirement to set back the low end of the bridge was proved at the end of the project when I attached strings and set up the intonation. As you can see, even with this 3mm extra using 010 strings, the low E string was on the back stop of the adjustment range of the bridge - a nervous moment. The final scale length for correct intonantion turned out to be 629mm for the high E (1mm more than theoretical). However the low E string length was 634mm (or 6mm longer). So even with the extra 3mm of recession on the bridge I still had to wind the saddle back another 3mm; which is pretty much end of range. You need to be hyper accurate when installing Tune-o-matic bridges!
Anyway, returning to our story, we arrive at the preparation for the paint job. At this point I was held up for about three months. The Gotoh Tune-o-matic bridge and tailpiece have to be ordered separately. The bridge came in the post fine, but the tailpiece got lost. I had to wait 30 days to do a claim and then they sent out a new tailpiece. This got lost too! So, not being able to source a Gotoh tailpiece in France for a reasonable price, I just ordered a Warmark generic Tune-o-matic tailpiece. This arrived fine and having seen the relative quality of the Gotoh bridge and the Warmark tailpiece, I would not bother paying top price for a Gotoh bridge again. A good Warmark generic should be perfectly fine.
The elements in place. I unscrewed the mounting posts and blue-tacked them in their measured places and then ran cotton thread from the nut end to check alignment. Fairly happy that the strings seemed parallel with the fretboard edges and that the saddles and tailpiece holes lined up, I was then ready to drill.
I had to find a friend with a pillar drill in order to be able to be sure to drill vertical holes. These were drilled about 0.5 to 0.8mm too small and then the pillar drill used to press the posts inserts into place. They are NOT coming out!
I improvised a paint shop in the boiler room of the school next door during the holidays! This had the advantage of being warm and undisturbed. It had the great disadvantage of having very little air flow. The undercoat was ok, but the nitrocellulose paint and the nitrocellulose lacquer in particular were deeply unpleasant. Even with a scarf over my mouth and nose and wearing safety goggles, it was hard to stay more that 2 minutes in the room. NOT fun!
First 'dust' coats of primer. Put on about 10 coats, one every 15 minutes, then left overnight. Used about half a can in total.
Headstock after rubbing down with 600 grade wet and dry paper before colour coats went on.
Colour coats going on. About 10 coats, 15 minutes apart. Used about a can and a half in total (400ml cans)
I asked my son what name he would like for the guitar. We talked and decided on Lazarus - the guitar that came back from the dead!
I found this graphic on the web and printed it in various sizes until we found the right size to fit the headstock. I then printed it on waterglide decal paper with my laser printer. You then cut out the logo, soak it in lukewarm water for 90 seconds, then slide it off the backing paper and leave it to dry overnight.
Here is the applied logo.
I then applied 15-20 coats of nitrocellulose lacquer (I lost count!). Put on thin dust coats, 15 minutes intervals and just keep going until the can runs out! Used one 400ml can.
The finished paint job. At this point I was going to let the lacquer dry for 2 months then do a mirror finish. This would be achieved by rubbing down the lacquer 'orange peel' surface with wet and dry paper (wet) going through the grades starting at 800, 1000, 1200, 1600, 2000, and 3000. Then using a rubbing compound (T Cut etc.) and then Jeweller's Rouge for the final polish.
Unfortunately I had lost so much time awaiting parts for the bridge I didn't have the two months to wait as I was due to relocate back to the UK and had to finish the guitar so I could leave it with my son here in France.
The re-assembled guitar. I re-wired the guitar using the original EMG81 active pick-ups. In the original configuration these had an active tone control which I wasn't convinced were doing anything good to the tone. I decided to remove this and just wire them with a straight-forward resistor-capacitor tone circuit. As active pickups need smaller value pots I had to source 25k Ohm pots (they recommend log profile for the volume control and linear for the tone control but I found by experimentation that log profile works best for both).
For the tone capacitor I chose 'paper in oil' type, as these are reputed for having good tone. EMG speficied a 0.1 microfarad, Duncan active pick-ups a 0.47 microfarad. I bought one of each value and decided to test for the best tone response.
Although specified for a 9volt battery supply, EMG81s can be run with a voltage supply up to 30 volts and people say that tone improves at the higher voltages. I tried a double battery 18 volt supply mod but didn't find any improvement. Also, given the fact that the void for the wiring / switchgear is quite small, it just made things very cramped.
The output socket is a stereo socket and the ring (Left channel) is used to switch the -ve battery supply. When a mono guitar lead is plugged in the L ring is shorted to the Ground connection, this completes the power supply circuit. This ingenious solution removes the need for an On/Off switch and prevents the batteries from draining. However it does mean that the guitar needs to be unplugged when not in use, which is good practice anyway, as it stops the jack socket losing tension on the connectors.
I had some fun and games getting the tone circuitry right. As the tone control is a low pass filter which alters tone by shorting a varying proportion of the higher frequencies to earth (controlled by the potentiometer resistance), the value of the pot (or even the capacitor) doesn't make that much difference to tone, just to the adjustable range. I tried using log and linear pots and found thet log seemed to work best. I experimented with a 0.1 uF (as recommended by EMG) and a 0.47 uF (as recommended by Duncan) and finally chose the 0.47uF as it seemed to give a slightly greater tonal range.All the tone circuitry debate and polemic needs to be taken with a pinch of salt, bearing in mind that most rock guitarists, most of the time, have both tone control and volume control at max, in which position they are effectively switched off, and don't do anything tone-wise. Which is why Eddie Van Halen didn't bother with them on his Frankenstrat! Nuff said!
Anyway, here is the finished wiring, note the use of ty-wraps to hold wires tigether. This is good practice as it gives extra supports to the individual wires and also prevents movement which can cause fracture, or insulation wear.
As the Epiphone Explorer originally had a tremolo it had string clamps on the nut. As a fixed bridge was being fitted the clamp had to be removed as the tuners would need to be used (rather than the tuning screws on the Floyd Rose bridge).
Given that Gibson Explorers with a Tune-o-matic bridge have an angled headstock, whereas the Epiphone Floyd equipped had a straight headstock, this meant that break angle of the strings over the nut was insufficient. Normally Gibson specifies a break angle of 14°. The following picture shows the very shallow string break angle.
In terms of playability there was no problem. But occasionally, when clipping a pick in between the strings, or handling the guitar, the B and high E string would pop out of the nut. A shallow angle is also likely to have a detrimental affect on tone. However the guitar actually was stable in terms of tuning and still sounded great. The tone was dramatically improved over stock. How much of this improvement was due to the addition of blocks of maple tonewood and how much to the removed active tone circuit, or the new tone capacitors, or the uprated power supply - is hard to know.
Anyway, string retainers (a.k.a. string trees) would have to be fitted to pull the strings down to the required angle. I chose roller type retainers as they are purported to offer less friction and thereby improve string life and tone. I ordered three double roller retainers in case all 6 strings needed to be pulled down. Although I would trial just doing the D G B and E strings first.
I ended up fitting retainers to all 6 strings. This improved the break angle, still not quite the 14° ideal, but quite close, probably around 10° to 12° or so.
Here is a front view of the fitted roller string retainers. A word of caution to anyone fitting these things. The screws are TINY and will withstand very little in the way of shearing force before snapping. So pilot holes need to be drilled the full inserted length of the screw. Also you need to stop tightening as soon as the screw pulls the retainer to the surface. Better to stop too early and have a retainer that sits a little proud, or rotates a little (it will find its position from the string tension anyway), than tighten too much and shear off a screw which is a major problem! Realistically drilling out such a small screw is just not possible, your only hope is to drive in the projecting part of the screw using a hammer and a flat-headed nail upside down to transfer the force to the screw, or to file the projecting part flush (but this requires great care to avoid damaging the paint job!). Once the screw is flat to the surface you can drill another hole, in front of or behind the first hole, hopefully the retainer base will cover up the old screw. Try not to do snap the second screw! Not a job for the ham fisted!
The finished guitar ready for giving back to my son.
One additional thing that is always a problem with Explorer style guitars is finding a guitar stand that fits them. As guitar stands increase playing time of any guitarist by a factor of three, having your guitars on stands is ESSENTIAL!
In order to provide my son with a suitable stand I decided to modify an ordinary guitar stand to fit the Explorer.
I cut a piece of wood wide enough to straddle the 'U' of the supports, then drilled holes that lined up with these prongs (19cm centre to centre). I then did the same with another piece of square section wood in order to kick out the bottom of the guitar to the right angle. I then hacksawed off the prongs flush with the surface of the wood. One key issue is to balance, as the U supports pivot, so the wood section needs to be pretty close to balanced, otherwise it would not sit flat.
I then cut a piece of wood that would form the guitar support - the strap button being used to locate the guitar securely in a hole. This piece of wood was then filed and sanded to fit the curved profile of the Explorer bottom.
Putting the stand on it's side I then placed the guitar in position and aligned the wooden base support with the Explorer bottom and then drew around this position with a pencil. I then drilled three holes in the middle of this pencilled outline and then put screws in these holes, placed the support back in position and pushed the screws in order to mark the drill positions. I then drilled the support and screwed it into place.
This picture shows the wooden block at the rear and the addition of black felt which was glued in place with contact adhesive in order to protect the guitar paintwork. You can see that I also had to dig out some of the wood in order to make space for the guitar strap to lie in.
Here is the final finished guitar stand mod - very happy with it!