post spacing tunomatic bridge

I've just got to the assembly stage of an Ex1, and found that the bridge spacing centre to centre is 74mm, but the body is drilled for 72mm, centre to centre.
I've looked online and bridges all seem to be standard 74mm size.

I'm not inclined to want to ruin my sonic blue nitro finish by filling the holes and redrilling for new post holes. It would be easier to start over with a new body.

A thought was to ? drill out the post holes in the bridge itself, 1mm on each post closer to centre, leaving oblong slots instead of round holes.

I can work around most things, but this has me stuffed.
Any advice would be greatly appreciated.

Cheers,
Colin

Hey Colin, an early mock build would have picked up this difference. Are you using the stock bridge or have you upgraded ?
I would drill or file the bridge holes and do a test fit until it fits. Wind the bridge posts almost all the way out and you will find it will fit on easier if the spacing difference is closer than 2mm

This has prompted me to look at my EX-1. I've bought Tone-Pros bridge and tailpiece for it but hadn't tried them for size until now - and they fit just fine, but the bridge spacing and the bridge post holes centres do both measure 74mm on mine. Stop-piece fits fine as well.

Obviously with two examples of EX-1s, you can't tell what the standard is, but others EX-1 builders don't appear to have mentioned an issue, so it is unfortunately, probably a quirk of your kit.

The post holes are often a bit smaller than they should be for the standard kit post inserts. They tend to be wider diameter at the top where the splines are (if you ignore the actual sticking-out bits of the splines but use the base of the 'V' slots for reference.

I don't know if this is the case with your kit, but if it is, then the holes could do with being enlarged a bit anyway, so using a file on the outer edges of each hole will help to move the centres out slightly. Even if you managed just 0.5mm on each hole, that's then a 73mm centre, which is closer than 72mm. You may then find that there is enough play in the post screws to fit the bridge on.

As Woks said, putting the bridge on with the posts almost fully out maximises the amount of play in the post screws (I think they are normally fairly loose on purpose to allow for slightly less than accurate hole drilling), which then means that if you bring both posts down together, you may hopefully be able to get the bridge sitting low enough, and also fitting nice and tightly (which is always a bonus for tuning stability and sustain).

If you've already pushed the post support inserts into the holes, then you've probably lost the ability to file out the hole positions.

But before you try filing out the bridge post holes, have you checked that the bridge is sitting centrally with respect to the neck? It is possible that one of the holes is in the right place but the other is 2mm out (rather than both being 1mm out). In that case, making both bridge holes 1mm longer won't help you much as you'll then have the strings running at an angle down the neck.

My understanding is that 74 mm is the spacing for Asian imports, and 72 mm is the spacing for USA Gibsons. If you want to avoid redrilling you can order a new bridge with American spacing. Here is an example from GFS.

Thanks for that link. But too late, I've gone ahead and attacked the bridge with a round file and ground out the medial sides of the holes.
It now fits, looks a bit ugly (irregular), but as they say, a man on horseback wouldn't notice.
I've strung it up and the strings run centrally, so problem solved.
Those GFS bridges seem to be the only ones of 72mm, so could be handy for future similar situations.

glad it worked out in the end Wolfred. You always have the option of upgrading to a 72mm bridge if you get sick of the ugly holes in the (I presume) stock bridge

I was worried I might be too late. I'm glad your modifications worked out though, and it's nice to not have to wait for new parts to arrive (and the bill). The GFS bridges are probably the most reasonably priced bridges at the Gibson 72 mm size, but any replacement meant for a USA build should also be available in that size too. I'm pretty sure Tone Pros lists their products as Standard for the USA size and Metric for the Asian size.

Just measured my Gibsons' bridges and they are all 74mm spacing. So there may have been some years when Gibson had 72mm centres (or more likely 2 13/16"), but they all now seem to be 74mm (at least since 1995).

Good call Simon. I've done a little more searching and it looks like Gibson does in fact use two different bridge post spacings. So far I haven't gotten any clarity as to exactly how to know which models will have which size, maybe ABR is 74 mm and Nashville is 72 mm. Basically what I've learned is that if the factory screws up on drilling the post holes, hope they err on the smaller side.

I replaced an ABR bridge (direct screw-in posts) on my Les Paul with a Nashville bridge (stud posts) so they were both the same spacing. Strange.