Installing Mastery Bridge Thimbles

[MattF]

Just a heads up for those of you who might be interested in joining the Warmoth Jazzmaster with Mastery Bridge "Club", I thought i'd pass along a little tip I implemented on my build. Mastery bridge thimbles are just a bit oversized to fit in the pre-drilled holes from Warmoth. It's probably an issue with the finish adding a bit of material to the hole, because there is not much wood that needs to be removed.

As I mentioned on my JM build thread, I read on another forum that a 3/8" drill bit will create a perfect size hole to accept the thimbles, so i decided to try something. I happened to have a newer 3/8" bit in the tool box, so I put a glove on and hand twisted it to bore out the hole a bit more. (The glove was for hand protection and a better grip) I didn't want to use a power drill for fear of something tragic happening, and it worked great. They went in with some hard pushing, but no hammer was needed.

 

[Glimmer]

That is a neat trick. I had tried to widen the holes using dowel and sandpaper but couldn't achieve a uniform bore, if that's the proper term. When I saw that, I wound up having the thimbles installed by a local tech.

It's also good to note here that if you send Warmoth the thimbles, they'll install them for a few bucks and then ship the body to you.

 

[Verne Bunsen]

I read that in your thread and gave it a try when I was doing mine. I think "newer 3/8 bit" is the key phrase, mine has seen some action and it was immediately wanting to take big bites. Didn't feel good at all. Went back to the dowel and sandpaper (and mallet) and that worked for me. Important tip there is to do your sanding with a rotating motion, no up and down, otherwise the top of the hole gets more action than the bottom and you end up with a taper, which isn't ideal.

When it comes to the Mastery thimbles, there is more to the tight fit than just accumulation of finish: they are actually 0.02" larger in diameter than a stock thimble! Might not sound like much, till you're trying to sand it away....

I think Glimmer is on the right track, it'd be worth the upcharge to have Warmoth pop them in!

 

[Glimmer]

I think Glimmer is on the right track, it'd be worth the upcharge to have Warmoth pop them in!

Were I to do another JM that's what I would do.

Had I known about it first time around, and had already thought the build through and purchased the mastery gear prior to buying the body, that's what I would have done.

 

[MattF]

I read that in your thread and gave it a try when I was doing mine. I think "newer 3/8 bit" is the key phrase, mine has seen some action and it was immediately wanting to take big bites. Didn't feel good at all. Went back to the dowel and sandpaper (and mallet) and that worked for me. Important tip there is to do your sanding with a rotating motion, no up and down, otherwise the top of the hole gets more action than the bottom and you end up with a taper, which isn't ideal.

When it comes to the Mastery thimbles, there is more to the tight fit than just accumulation of finish: they are actually 0.02" larger in diameter than a stock thimble! Might not sound like much, till you're trying to sand it away....

I think Glimmer is on the right track, it'd be worth the upcharge to have Warmoth pop them in!

Mine was definitely sharp, so I didn't have any issues. I went very slowly of course. The majority of the material i removed was in the upper 1/3 of the opening, so that's why I was thinking it was mostly finish. Warmoth said their bridge holes were 9mm, but I never found the size of the mastery.

 

[Verne Bunsen]

I mic'd the Mastery thimble at 0.375", which Google tells me is 9.525mm. The stock thimble I had was 0.355", or 9.017mm. The stock thimble was actually able to fall into the hole before the Mastery thimble would even start! Odd thing is that the ID of the Mastery thimble is actually a bit tighter than that of the stock thimble (by feel, not micrometer), so not sure why the OD should have to be larger? Probably where all the extra tone comes from  :toothy12:

 

[Cagey]

...not sure why the OD should have to be larger? Probably where all the extra tone comes from  :toothy12:

Indeed. You want a "press fit" so there's a good, solid mechanical connection. Tuners are the same way, as is the neck joint. Any joint that is less than rock-solid is a tone/sustain robber.

 

[overdrive535]

What I did was dowel/sandpaper the finish down a bit, then used my deep throat arbor press to press in the thimbles.  Solid connection between the bridge and the body.