Gibson bridge posts

nero1701

Recently purchased a Memphis 335 which originally would have had the Tonepro bridge which has small allen screws which clamp the bridge to the post..

It came with an aftermarket roller bridge which I don't like.

I have a Gotoh bridge which is the correct spacing between the posts but is metric holes at 4mm. the posts are 6/23 imperial size.

I've had a look online but no joy, does anyone know if there are posts which are 6/32 on one side and 4mm on the other?

BillDL

Just to be clear, you are talking about UNC 6-32 posts that are 3.5mm in diameter and are therefore 0.5mm too small for the diameter of the 4mm post holes in the Gotoh bridge and there will be some play on the bridge?

The most likely manufacturer to make studs with imperial thread on one side and metric on the other is Faber.  They make some conversion posts but not in the 4mm to 6-32 you need.  These posts are screwed directly into the top and down into the centre block (i.e. no body bushings), aren't they?

How original do you want to keep the guitar?  I would be inclined to buy long stainless steel Allen keyed "grub screws" in 4mm and screw them into the body allowing them to make new threads in the wood as they go. Stainless steel ones will be hard enough to do this without breaking but the difference in size should not be enough to crack the wood.  If you needed to revert to originality you would have to glue the old 6-32 posts back into the oversized holes with epoxy resin.  I've done this by first greasing up the posts, then partially infilling the holes with "steel" epoxy and swirling it in the hole with a toothpick to void bubbles, and pushing the posts in with a wee twist so the still-runny epoxy goes into the threads of the posts.  The grease on the posts should stop the glue from adhering to the posts and should leave an internal thread so they can be adjusted up or down.  I tested this first on a scrap piece of wood to make sure the epoxy didn't stick to the greased-up posts.

nero1701

Spot on @BillDL ;, my bad for presuming it was imperial rather than UNC.

Great informative reply as always.

Seziertisch

I have metric bridges on 6-32 posts on a number of guitars and have had no issues. 

In fact, on a Bigsby-equipped guitar with domed thumbwheels the extra post hole width on the metric bridge aids the rocking motion.

Otherwise, I’m not a fan of Tuneomatics with locking screws (I previously had Callahan’s on a number of guitars). Anytime I compared locked to unlocked I preferred the sound of the unlocked. Locking gave an extended bass and treble response but also a “harder” overall sound.

ICBM

You don’t need to change anything. The string tension will hold it tightly in place anyway.

nero1701

ICBM said:

You don’t need to change anything. The string tension will hold it tightly in place anyway.

I get that the tension holds it down, my concern is that may intodice enough slop in the bridge position to impact the intonation?

ICBM

nero1701 said:

I get that the tension holds it down, my concern is that may intodice enough slop in the bridge position to impact the intonation?

No, because the bridge will be held tightly in the furthest forward position - because of the string break angle there is large forward force on the bridge. If you set the intonation with it there then it won’t move.

nero1701

Thanks @ICBM ;

nero1701

To close this out, 

@BillDL kindly sent me a couple of 4mm Stainless 30mm allen keyed grub screws,  I popped them in last string change.

I have no doubt that the advice offered above was accurate, I just like thinks to fit as well as well as possible. 

PAL

If there is a little play in the bridge just cut and fit the smallest size heat shrink over the post. You can cut them so they don't 
  protrude above the top of the bridge. Hope this helps. 

nero1701

PAL said:

If there is a little play in the bridge just cut and fit the smallest size heat shrink over the post. You can cut them so they don't 
  protrude above the top of the bridge. Hope this helps. 

Nice tip