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 Post subject: thompson belly reducer
PostPosted: Mon Mar 31, 2008 9:05 am 
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Cocobolo
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stew mac item#1380.
Is this a permanent fix?
would be less work and less intrussive than removing the bridge plate.
I have a 1968 D28 that I've been waiting to repair till I'm a little more confident in removing the Bridge plate. For me thats a scary job. eek
I would't mind giving the belly reducer a whirl if the report card on it is good.
Peter


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PostPosted: Mon Mar 31, 2008 10:08 am 
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"4. Place the bridge template on top, convex side down. Gloves will be necessary.

5. Hold the bridge plate flattening tool in place on the bridge plate with concave side facing up.

6. Insert a bridge clamp through soundhole and clamp the two parts together, maintaining alignment of both tool parts."

Well, I'd guess that it works for TJ (who is very highly regarded), but I'm having a little trouble seeing how you have a gloved hand inside the guitar holding the plate tool in place, while simultaneously holding the top plate in place with another gloved hand, and simultaneously getting a clamp in and centered on both tools and tightening it.

I'm also not sure that the way this is flexing the top is going to have the right effect on the bellying behind the bridge. It may work for some bellies and not well for others. The way I'm seeing it (and again, TJ has an awfully good reputation) if you have the bridge off, it isn't that big a deal to replace the plate and do it right, and this new tool system offers quite a bit of opportunity to make things no better or even worse. Much as I love StewMac, some of their tools seem to me to be aimed at people who are afraid to do certain jobs that they have no experience with, and are looking for an easy fix instead of learning how to really do the job.

And, are you sure your 1968 Martin is glued with hide glue?

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These users thanked the author Howard Klepper for the post: Pmaj7 (Thu Jan 26, 2023 3:25 pm)
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PostPosted: Mon Mar 31, 2008 10:23 am 
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the bellying on my 68 is more behind the bridge.
It's my understanding that martin was'nt using hide glue in 1968.

Peter


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PostPosted: Mon Mar 31, 2008 10:36 am 
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Howard Klepper wrote:
And, are you sure your 1968 Martin is glued with hide glue?


From what I've heard Martin switched to white and then yellow glue quite late, in the late '80 perhaps?

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These users thanked the author Laurent Brondel for the post: Pmaj7 (Thu Jan 26, 2023 3:25 pm)
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PostPosted: Mon Mar 31, 2008 10:52 am 
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As Howard said, TJ is certainly an excellent repair man and builder, but he also has his own ways of working, no doubt. I'm sure he gets results with this, but it wouldn't surprise me if he has nuances and processes to using these tools that go far far beyond the StewMac instructions. And though I do like to preserve as much original material as reasonable, this seems to fall more in line with TJ's preservation goals which are certainly more extreme than my own. If a side has an irregular shaped hole punched in it, I would have no problem shaping it to one more easily plugged, while I've seen TJ patch incredibly complex holes without reshaping simply to preserve as much original material as possible (and does an incredible job). If a top is bellied up enough to warrant plate work I feel replacement is not only acceptable, but a more preferable and reliable repair. So I don't always see less intrusive as better - sometimes a joint requires intruding upon.

And I too am a bit confused by the shapes. I have done similar top pressing in the past, but I've just cut my own aluminum cauls and mounted heater cartridges and thermocouples to monitor. I didn't curve my plates as they show theirs though. If I remember right I left them flat in the direction they have them cupped, and flexed the top how I wanted by using the clamp as a lever and jacking up the end. I've only done this a few times, and results were okay. For me this was an experiment in a quick fix, and though the results were acceptable I didn't feel comfortable guaranteeing the longevity of the repair. They may or may not last, we'll see...

And that's probably a massive rosewood plate - I have a 67 and 68 in the shop right now, and they are just before and after the big plate change. I though I had some pics around of the last big rosewood plate removal I did, but can't seem to find them. Anyway, if you decide to pull it, there are a few tricks. Or if you decide to try the StewMac tool, let us know how that goes too.

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These users thanked the author David Collins for the post: Pmaj7 (Thu Jan 26, 2023 3:25 pm)
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PostPosted: Mon Mar 31, 2008 10:55 am 
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Oh, and I haven't gotten in to the '67 yet, but I can tell you that the '68 I'm finishing up right now had plenty of PVA glue from the factory. Generous amounts in the neck joint, even if the surface was never meant to be glued.....

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PostPosted: Mon Mar 31, 2008 11:12 am 
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mid '65 was the change from hide to PVA....

How bad is the belly, and does it really need "fixing"? I've only ever seen one(1) belly on a Martin that was bad enough to warrant intervention.


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PostPosted: Mon Mar 31, 2008 11:18 am 
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Once you have clamped a hot aluminum plate inside the guitar you have basically done what you need to do to take the old bridge plate off. So I think David is right that TJ was mainly concerned with preservation of the original parts. The StewMac page mentions keeping the guitar original, but also gives the impression of being for making the job easier.

Back in the 70's, Matt Umanov and his crew put oversize bridge plates into a lot of old (prewar) Martins that had excessive bellies. A couple of the guys who did repairs there have told me the rule of thumb was to put in as big a plate (big as in width) as you could get through the sound hole. This may sound shocking, but a lot of very good players who had experience with old Martins (e.g., David Bromberg) agreed that these guitars sounded better with big plates. Not just better than when they had the big bellies, but better than other similar prewar Martins with their original plates.

The pendulum has swung way back to preservation at all costs, and staying as close to original as possible if you have to replace. Preservation is an important consideration, but I'm with David in that I don't think it's a sacrilege to make some alterations, especially where a repair is already needed, especially where it will not be seen, especially to make the guitar a better tool for the player if it isn't a museum piece.

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PostPosted: Mon Mar 31, 2008 11:43 am 
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This may be a slight bit off topic, so if it is and offends you, scroll right on past and ignore what I have to say.

I am still amazed at how the "Standard" for the industry is still the sound of the pre-war Martin. Every pre-war martin I have seen has been in disrepair, or as this thread states it needs some help with an excessive belly, a crack, or some other defect. Frank Finoccio's shop is full of tops from these pre-war martins, and from what I could see the craftsmanship was shoddy at best. Not just the top, but the rest of the inside of the guitar as well. Of course shoddy craftsmanship doesnt always mean bad sound, but one would expect better.

If one of these needed a little TLC to bring them back to a working condition, I could understand the fuss. On the other hand, I cant see putting a lot of effort into a guitar that is "marginal" at best. We all know that people want to believe in "old wives tales" so much that they will spend good money on less than reasonable guitars or poor quality guitars. Why not put a better or larger bridge plate in the guitar if it brings it to life?

I just have to scratch my head and wonder why??

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PostPosted: Mon Mar 31, 2008 12:02 pm 
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I can see from the variety of viewpoints here, this thread is going to be much longer and more lively than a simple tool revue.... beehive

Eat Drink

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PostPosted: Mon Mar 31, 2008 12:06 pm 
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and wonder why??

If you find a great one, and love that sound, it's the only sound that will do. That's why. But the tone isn't for everyone, and certainly not for ever genre of music, either.

The larger bridge plates make the guitars sound tighter, more focussed, which many players would indeed consider "better", but it's truly not the prewar Martin tone. Today, we can have that more focussed tone from most any modern maker's guitars, so it makes sense to revert the prewars to the way they are supposed to sound.



These users thanked the author grumpy for the post: Pmaj7 (Thu Jan 26, 2023 3:30 pm)
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PostPosted: Mon Mar 31, 2008 12:06 pm 
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It's been a while since I've looked at this guitar.
I checked out the inside, it has a small maple B plate, if it's been changed from a rosewood plate it is an extreamly clean job.
I took some pics to show the bellying.
at the end of the ruler the gap is 9/64"
the guitar plays resonably well but am running out of saddle.
I'm thinkin' if the belly were flattened I'd get some saddle back. http://i246.photobucket.com/albums/gg11 ... C02243.jpg[/img]ImageImageImageImage[/img]
oops_sign I just can't figure out this picture sizing thing. [headinwall]
thanks for looking
Peter


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PostPosted: Mon Mar 31, 2008 12:10 pm 
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Koa
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PMTE would likely fix that one...

As nasty as it looks, it's still not terrible. How long has it been like that? Wood has a plastic limit, and this one has likely reached its limit if it hasn't moved further in 5 years or more. If that's the case, and most likely is, then I'd fill the saddle slot, re-cut it slightly angled to the rear, making it perpendicular to the top, and reset the neck if the action is too high. Then I'd enjoy the guitar....

Bellies happen.


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PostPosted: Mon Mar 31, 2008 12:22 pm 
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Mario, what is PMTE?
this belly has certainly been there for more than 5 yrs. It does not appear to be getting any worse.
Can you tell me please, what is the cure for a belly ache? larger plate?


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PostPosted: Mon Mar 31, 2008 12:42 pm 
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"patented Mario tone enhancer"
also known as another brace behind the brige plate-I have a patent on them as well!


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PostPosted: Mon Mar 31, 2008 12:50 pm 
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Brazilian Rosewood
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With that bulge and warped bridge I would certainly be inclined to remove and flatten the bridge and replace the plate with a slightly oversized one. If the belly were spread across a wider area I may not be so eager to change it, but when it's focused directly between the braces and the bridge itself is warped to that extent I become concerned with potential for developing cracks.

How is the line in front of the bridge - is it flat, or is there any significant dip in the center? And not so directly related, how is the pickguard and surrounding wood holding? Chances are good that with any work you do, a neck reset is probably about due as well.

And just out of curiousity, what's the serial number, somewhere in the early 23xxxx?

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PostPosted: Mon Mar 31, 2008 1:30 pm 
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grumpy wrote:
mid '65 was the change from hide to PVA....


Not to argue, because I was still sucking on baby bottles and wasn't there, but I heard from somebody who worked at Martin that they were still using hide glue…

BTW I would check that there are no gaps between the x-braces and the top on each side of the bridge plate.

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PostPosted: Mon Mar 31, 2008 1:36 pm 
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when I put a straight edge on the top ahead of the bridge it shows the top being dead flat and it doesn't appear that the top from hole to bridge is sloping at all.
it has been cleated for the b string crack.
the pickguard is not lifting at all and the surrounding wood and
profile all seem good.
serial # 232712
thanks again,
Peter


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PostPosted: Mon Mar 31, 2008 1:47 pm 
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If it's not dipped in front of the bridge that's a good thing. I still would likely go ahead with pulling and flattening the bridge and replacing the plate though. The b-string cleated crack of course says the pickguard has shrunk enough to pull and crack the wood, which will slowly continue to pull of course.

As to PVA or hide, here's a shot of a '68 reset I'm just finishing up. PVA, and plenty of it, not only on the dovetail (where much of the PVA filled gaps), but on the face of the heel and dovetail as well. idunno Not a big deal, just a bit more work in the reset.

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PostPosted: Mon Mar 31, 2008 2:49 pm 
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Well, it so happens that my belly has grown pretty large, starting coincidently around the time I got married. Whatever this thing is, if it will reduce that, I'm buying it.

Oh wait....um......I think you guys were talking about something different...nevermind.

:oops:

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PostPosted: Mon Mar 31, 2008 3:04 pm 
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Yeah, I thought they were talking about that pushing away from the table exercise, since my name is Thomson, and they just didn't know how to spell it.

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PostPosted: Mon Mar 31, 2008 3:46 pm 
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I'm with David on the Dx and Rx here. Not so bad that it couldn't go for a while if it's playable, but pretty clearly in need of flattening if you look at both the rise relative to the rim and the tilt of the bridge. I don't think there's anything odd about a maple plate from that vintage; it's very unlikely to be a replacement. New plate ought to be about 1/4 to 3/8" wider toward the belly side; exactly how much is a judgment call. Expect to put on a new bridge--the existing one has been cut way down in front. Flattening the top will bring the action down but going back to the standard (3/8" +/-) bridge height will raise it. If the action is high now, it will likely need a neck reset. All of which is routine overhaul for a 40 year old Martin.

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PostPosted: Mon Mar 31, 2008 4:11 pm 
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Don and Waddy if you guys need a PMTE installed this is one time that pics would not be a good idea depending of course on what method you use to install the PMTE......... :D


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PostPosted: Mon Mar 31, 2008 7:40 pm 
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Location: Is this heaven? "No, it's Iowa."
For what it's worth, I believe it was Norman Blake who said... "Never trust a guitar without a belly."

long

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PostPosted: Mon Mar 31, 2008 8:07 pm 
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Bob Long wrote:
For what it's worth, I believe it was Norman Blake who said... "Never trust a guitar without a belly."


There's a difference between a belly and a hernia.... ;)

I don't get alarmed at what I would call a healthy load in a top, but what I see here is well out of that range in my opinion.

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