Gibson J45 Bridge, ever seen this?

BBLong · #1 06-08-2021, 04:12 PM

Hi, all,

I have been a member for a long time but took quite a break from online for a while. I am back, but had to make a new account.

Anyway, I am working on a Gibson J45 from the late 70's or early 80's (part of the serial number is covered with a name and 77). Action is a little high and the bridge plate might need to be replaced. The owner does not want a neck reset. Instead, he insists the bridge be taken down some. The bridge is much thicker than most I've ever seen in 30+ years of working on guitars, so there is room, and the saddle slot has lots of room to go down, also. Still, not sure I like doing it that way. I may punt for this reason, and for the reason that it has this bridge, which I have never seen before this guitar, but it is standard on this era of J45 (see the pic, below).

I know nothing of this and can't find any info on it on the net. I'm sure someone here has seen it. Do any of you have any idea how it is constructed? Is this the actual pickup? Is it an insert to cover a pickup? Thoughts? Ideas? I really think the guitar needs a neck reset and a refret but the owner is insistent on not doing that. I may punt, but I still want to learn about this bridge for future reference. It's a new one to me, and I like to know everything I can before diving in or making decisions on something like this.

Thanks, in advance,

Bob

Zigeuner · #2 06-08-2021, 05:15 PM

I would never shave a guitar bridge. I'm aware that there are greater difficulties in dong a neck reset on a Gibson acoustic since among other things the finish covers the neck joint. Also some of the Gibson dovetails are a little odd and may require more effort to steam apart.

Shaving a bridge will definitely affect tone and volume negatively on an acoustic guitar. If the customer can live with that, then OK.

All that said a neck reset would be best. JMHO, YMMV.

NotALuth · #3 06-08-2021, 05:22 PM

Hi Bob,

Like you I don’t recall seeing one of these, but from Chapter 12 of Gibson’s Fabulous Flat-Top Guitars under the heading ‘Bridge Facts’ it states:
…In the ‘70s a fiber insert was inlaid into the bridge-pin area to avoid the problems with splitting common in bridges of that era. It’s no wonder that these bridges split - they were made much too thin so as to compensate for the often under-set necks of the ‘70s.

Regards,
Clive

surveyor · #4 06-09-2021, 08:06 AM

What about the "belly"? If you measure that and that is a factor then you could justify removing the bridge and plate with heated cauls and clamp for several days to flatten it out.. Then replace the old plate and glue the old bridge back on. Only one other way I can think of without a neck reset and that would be to "slip" the neck block by undoing the back and regluing. I know a pro would never do that but I have and it works. Just cosmetic issues will happen.

Frank Ford · #5 06-09-2021, 08:21 AM

Standard stuff from the period. Just a hunk of phenolic or something similar inlaid there. No pickup - probably some mid-level engineer's "improvement" to avoid cracks between the holes

redir · #6 06-09-2021, 08:56 AM

How thick is the bridge?

BBLong · #7 06-09-2021, 12:22 PM

Quote:

Originally Posted by Zigeuner

I would never shave a guitar bridge. I'm aware that there are greater difficulties in dong a neck reset on a Gibson acoustic since among other things the finish covers the neck joint. Also some of the Gibson dovetails are a little odd and may require more effort to steam apart.

Shaving a bridge will definitely affect tone and volume negatively on an acoustic guitar. If the customer can live with that, then OK.

All that said a neck reset would be best. JMHO, YMMV.

Agreed. I don't want to shave the saddle. I thought about since this one is really, really thick and the customer requested it. I just can't bring myself to do it. I thought about b/c the thickness of the bridge may also inhibit the tone, but this insert is probably making it even worse. I think I'll pass. I like to do it right or not at all.

Thanks for your input.

Bob

BBLong · #8 06-09-2021, 12:25 PM

Quote:

Originally Posted by Frank Ford

Standard stuff from the period. Just a hunk of phenolic or something similar inlaid there. No pickup - probably some mid-level engineer's "improvement" to avoid cracks between the holes

Hi, Frank. I am forever indebted to all I have learned from you over the years. Between you and Dan Erlewine I've saved myself a lot of time and heartache by using your info instead of trial and error.

There's a pickup in the guitar, but it is either on the bridgeplate (haven't even looked inside yet), or under the block of resin. Anyway, thanks for the response.

Bob

BBLong · #9 06-09-2021, 12:34 PM

Quote:

Originally Posted by NotALuth

Hi Bob,

Like you I don’t recall seeing one of these, but from Chapter 12 of Gibson’s Fabulous Flat-Top Guitars under the heading ‘Bridge Facts’ it states:
…In the ‘70s a fiber insert was inlaid into the bridge-pin area to avoid the problems with splitting common in bridges of that era. It’s no wonder that these bridges split - they were made much too thin so as to compensate for the often under-set necks of the ‘70s.

Regards,
Clive

That's the info I needed. It's phenolic resin, makes sense. I figured it was a Norlin era design to "improve" things. This guitar, as others, does have a factory pickup, or at least several I have seen have the same setup with the same input jack in the same place, so I'm guessing some had pickups, some did not. I will look inside the guitar and make sure and share any info.

I thank you, profusely, for that info. I will look into the book and read about it.

Thanks,

Bob

BBLong · #10 06-09-2021, 12:36 PM

15mm thick, to 16mm in the middle. That's pretty thick compared to most I've worked on.

Bob

BBLong · #11 06-09-2021, 12:38 PM

Surveyor,

There's not much belly. It does not need a belly reduction and there really is no reason to take the bridge off. Ultimately I think I'm gonna pass on this one. But I love learning more about guitars, so this is kind of fun.

Bob

redir · #12 06-09-2021, 12:51 PM

16mm? It can't be that thick is it really? If it is then yeah that's way overbuilt. I would be tempted to make a new bridge, saving the original one, and that would give you plenty of room to get the action right and probably make a huge improvement in tone. It would also be cheaper than a neck reset.

ArchtopLover · #13 06-09-2021, 03:15 PM

Quote:

Originally Posted by Zigeuner

I would never shave a guitar bridge.

Shaving a bridge will definitely affect tone and volume negatively on an acoustic guitar.

I disagree.

If the bridge was too thick to begin with, shaving it can improve the tone. A 16mm tall bridge is over built IMO and I believe it can be safely shaved a good 3mm to 4mm in order to lower the string action and negate the need for a very expensive neck reset, without affecting tone in the negative.

Bridge shaving is an acceptable method of Luthier repair when there is an ample amount of material to deal with and shaving a 16mm thick bridge should not be a problem.

I've done this on a 1994 Gibson J-35 reissue that had a narrow, 9/16" tall (14.25mm) retangular ebony bridge and I removed almost an 1/8" of an inch in height. I cut the original saddle slot an 1/8" deeper, shaped a new, taller saddle, and wow what a difference. String action was greatly improved, there was no change in the intonation (which I was concerned about), and the guitar became far more responsive and way more comfortable to play at the higher registers.

Nevertheless and thankfully, in this case, there was no need for a neck reset. The neck angle to the body was fine, Gibson just used a overly thick slab of ebony for the bridge, and set the saddle low to compensate.