First up I noticed both bridges have near identical pillar, or stud spacing. The tunomatic is 2 & 29/32" (73.81mm) between centres & Mustang bridge I have is 73mm. The Mastery will do both happily with the post screw loosened off there is nearly 1 mm "wriggle room". The studs for the TM (tunomatic) are 11.13mm at the top knurled bit & 11.03mm on the smooth lower section, 7/16" (11.11mm) in anyones money. I tried a 7/16" shank down the stud holes and it was a tight fit.
The holes are 28.3mm deep aprox, both sides.
Studs are only 22mm long so a lot of it is sitting in space! Hmmm.
Mastery Bridge posts are machined .004" under 5/16" at .308", (5/16" is .3125").
The plan is to drill some 7/16" machined round Brass Rod using a 5/16" HSS drill bit. This one comes in at .310" on the shank, (not the most accurate way of measuring but the tip came in roughly the same).
Thing is, "How do I accurately drill a 5/16" hole down a 30mm lenght of brass tube, heres a tidy method I picked up from a machinist's Forum, The Reverse Drill Press Drill method. Heres my 10 cents worth on it:
First pick a small drill that can be reversed into your press drill chuck. This DOES NOT WORK with larger sizes than about 5mm or it bites on the flutes & goes off center, badly. It helps if the drill is short enough to leave some of the unflutted plain top, in the chuck to center it.
Check every thing is square.
Lower drill into a machinists type vice, and tighten the vice onto the drill shank. It is now centered, so clamp the vice to drill base.
Now insert the 30mm brass rod section into the drill chuck.
Bring the chuck down to just touching the drill bit poit.
The Mastery Bridge thimble is 18.5mm deep.
Set the drill depth stop to 18mm ish.
Wind the drill up to its highest speed setting.
Bring down the chuck ever so GENTLY on to the drill point. The idea is that the drill will self center on the piece in the chuck, like on a Lathe, and leave a minute center bevel.
Now go to half speed.
Same again, only slightly more presure. To much pressure & the drill will flex, no good at this point.
Now set the drill back to its lowest speed and start pressing down & cutting, a spray of WD 40 helps.
Lift & clear chips frequently, keep going down to 18mm set on depth stop. Heres the finished result.
Now to get this bored out to 5/16 or .3125". First up place the drilled rod in the vice, this one has an accurate vertical V in the rear jaw making this a doddle.
Then very carefully lower the 5/16" HSS drill, by eye, to center it near as you can before switching the drill, then cut a very small bevel.
The chuck will now have centered itself so long as you have been carefull, and not let the drill "Grab" & fling the whole assemble accross the room. Clamp the vice down, and start drilling.
Heres the finished pair getting the face sanded working up to P800, for a nice brushed looked. As it is sat under the bridge it is hardly worth polishing.
Now lets try these in the guitar!
They are tight! Went in about 10mm and stopped, nice.
There is an earth wire in the treble side post hole, this lead me to dreaming this idea up, rather than use a wooden plug. Heres a test fit of the bridge with the post screws loosened.
Looking good, now to press the bushes the full 28mm so they bottom out in the stud holes.
I finally tapped them fully home with a copper drift & hammer over a scrap wood block to prevent damageing the soft brass. The are both 2mm from flush with the body & level roughly with the face of the pickguard. THere is hardly any rock or movement at all they are tighter than the Mastery thimbles, I guess aboy .002-3" clearance. This turned to rock solid when I tightened the allen screw heads to lock the posts. Nice.
Now for a set up, first set the bridge saddles to 7.25" radius, having set top E string to 3/64" at 17th fret & low E at 4/64". Once thats set just lower the middle saddles untill they "Buzz" on the under string radius guage (resting against, & damping the 2 outer strings) & job done, apart from intonation & fine tuning.
Finished set up, this bridge is sitting fairly low, I have had to raise the posts about 1 1/2 turns only to get it up to the right hight, so looking good.
String spacing is spot on.
What lead to the idea was how to to make a spacer for the .374" (9.5mm) Mastery thimble to fit the 7/16" (11.11mm) without drilling out & plugging the thimble holes. The earth wires said something conductive might help- Brass Rod, as it come in 7/16", easily machined and will give a very tight fit, so long as the holes are centered corectly.
This worked a charm, have set the thing up before I did this post and man, is this thing Resonant! The brass rods are cut 30mm BTW, so the whole 28mm or so has been pressed all the way home in the wood, very tight, BUT NO GLUE OR DRILL OUT SO THE WHOLE THING IS REVERSABLE, should Ben want to sell the Guitar with original bridge. (I wouldnt want to be the one who pulls those brass out though, they are tight!) I cut & filed the rods down to 30mm by the way, so they would bottom out in the stud holes & leave 2mm proud, they went in tight the last 10mm or so!
Anyway, I hope Ben will be pleased, it has way more tone & sustain, as usuall with the Mastery Bridge & I hope this will work for anyone without a Lathe, who wants to convert their "Thurston" to Mastery tone & stability. I love the things, so easy to set up as well.
Forgot to add the bleedin' obvious. The "Thurston" string spacing is Gibbo-ish 52mm with the TOM bridge, this take it up to correct USA string spacing of 56mm- 2 3/16". Also there is no "Dead Air" space under the posts, just 12mm, or 1/2" of solid brass rod. Got to give some "Mass" to the equation, like on the Strat Trem steel block Thingy. No expert mind on Strat stuff, but think its the same principle. Think string energy transfer. With such a low break angle over the bridge every little helps methinks. Its amazing how much tone a JM can produce considering but the Mastery bridge seems to transfer more IMHO. Thats my 10 Cents up.
Hope this has been of interest.
