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Bridge Doctor
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=54189		 Page 1 of 2
Author:  Mike OMelia [ Sat Jun 05, 2021 2:06 pm ]
Post subject:  Bridge Doctor
I ordered a few of these for some repair work. (Belly bulge). The first one was installed on a 1969 D28. Bulge was moderate. It completely leveled the bridge. I'm a huge fan!! Still had to reset the neck to regain proper string height. Found a cool estimation formula to estimate new angle on heel. THat too worked like a dream. This old Martin is a player again!
Author:  Mike OMelia [ Sat Jun 05, 2021 2:16 pm ]
Post subject:  Re: Bridge Doctor
https://hazeguitars.com/blog/neck-reset ... we-measure

for the formula
Author:  jfmckenna [ Sat Jun 05, 2021 8:38 pm ]
Post subject:  Re: Bridge Doctor
I've tried them a few times and never really liked the tone of the guitar after installing them. But a lot of people claim it enhances their guitar tone too. No doubt the device does what it says it does. It flattens out a caved in top for sure. But it seems to me, at least for a responsive guitar, it chokes it out. It does at least make it playable though.
Author:  Pat Foster [ Sat Jun 05, 2021 10:51 pm ]
Post subject:  Re: Bridge Doctor
One guitar I used a bridge doctor on had a thin, floppy plywood top with unfocused, flabby tone. After the installation, its tone, while not great, was much improved.
Author:  CarlD [ Sat Jun 05, 2021 11:28 pm ]
Post subject:  Re: Bridge Doctor
I had the opposite experience than Pat with a 30's SS Stewart on which I reset the neck. It had a ladder braced birch top with a significant belly. Sounded OK before but the sound was quite negatively effected by the B Doctor, although it flattened the top. I've thought about x bracing the top to see how that would change it.
Author:  Chris Pile [ Sat Jun 05, 2021 11:31 pm ]
Post subject:  Re: Bridge Doctor
I've not been asked to install them, nor would I. I think they add too much mass to the top. I have been asked to remove them by two different clients (both Breedloves that had them installed at the factory).
Author:  bluescreek [ Sun Jun 06, 2021 5:48 am ]
Post subject:  Re: Bridge Doctor
not a fan most times the bulge is a result of loose braces or other reason.
Will it flatten the top? yes it can also change the tone.
in the martin world this takes money off the guitar.

martins should have a small belly on them. if you place a straight edge across the top you want to see less than 1/8 in
Author:  Mike OMelia [ Sun Jun 06, 2021 8:06 am ]
Post subject:  Re: Bridge Doctor
This one sounds pretty good. I guess mileage will vary?
Author:  Chris Pile [ Sun Jun 06, 2021 8:59 am ]
Post subject:  Re: Bridge Doctor
There are few absolutes in life when it comes down to it.
Author:  Pat Foster [ Sun Jun 06, 2021 11:37 am ]
Post subject:  Re: Bridge Doctor
Chris Pile wrote:
There are few absolutes in life when it comes down to it.


Absolutely!
Author:  Freeman [ Sun Jun 06, 2021 4:32 pm ]
Post subject:  Re: Bridge Doctor
A long time ago when my old Martin 12 string developed a bit of a belly and its action was getting pretty high I thought maybe a Bridge Doctor could cure it. Not wanting to drill any holes in an old Martin, I installed the kind with the little brass "pins" that hold it in place. Short story, it didn't seem to do anything to the belly and it killed the tone. I took it out, its been under my workbench ever since

It weighs right at 2oz when you add the 7 inch dowel that goes to the end block

Attachment:
IMG_6735.JPG


For comparison a Martin belly bridge weights 1.15, a pyramid bridge 1.0. So you have added roughly twice the mass of the bridge hanging down under it.

And if you stop to think of how the bridge doctor works, countering the string torque with a little lever that is pushing against the end block, and if you believe, as I do, that a pinned bridge makes sound at least in part by rocking about its axis, then you have to consider whether this thing is beneficial.

I've seen pictures of factory guitars that come with the BD installed - they are very highly scalloped. It looked like the Doc was somehow making up for very weakened bracess. And remember that that particular manufacturer only installs the Doc in some models.

The 12 string? Oh, it got a neck reset which is what it truly need and it now has a slight belly, great action and lovely sound.
Author:  Chris Pile [ Sun Jun 06, 2021 5:12 pm ]
Post subject:  Re: Bridge Doctor
Quote:
And if you stop to think of how the bridge doctor works, countering the string torque with a little lever that is pushing against the end block, and if you believe, as I do, that a pinned bridge makes sound at least in part by rocking about its axis, then you have to consider whether this thing is beneficial.

I've seen pictures of factory guitars that come with the BD installed - they are very highly scalloped. It looked like the Doc was somehow making up for very weakened braces. And remember that that particular manufacturer only installs the Doc in some models


My thinking exactly. You built a guitar that you planned to fail, so you included a fix? Weird.
Author:  Hesh [ Mon Jun 07, 2021 4:19 am ]
Post subject:  Re: Bridge Doctor
Chris Pile wrote:
I've not been asked to install them, nor would I. I think they add too much mass to the top. I have been asked to remove them by two different clients (both Breedloves that had them installed at the factory).


This is our experience with them too, we won't touch them or install them.

Belly is not necessarily a bad thing. If there are underlying causes for the belly such as bridge plate damage, lifting bridge, loose braces fix all of that and the belly usually is back in an acceptable range. What's an acceptable range? Some forward lean is OK provided that it does not move the saddle forward enough to prevent proper intonation.

You know all that we do, the entire point of the design and engineering of an acoustic guitar today is to free the most valuable real estate on the guitar, the top to free it up to vibrate AND pump. Mario once brought it all home for me when he described an acoustic guitar as not unlike a fireplace bellows.

Using the bellows analogy a bridge doctor is so counter to how a guitar is supposed to work.

Wanted to mention too that there are Martins, lots of them that need the saddle relocated too, 70's sorts so this is always something to be on the look out for when resetting a Martin or dealing with an excessive belly. Again a belly is not a bad thing, an excessive one may be.

Back to the bridge doctor the notion of added mass and although only a couple of ounces depending on your perspective you might say "yikes gaah it's adding a couple of ounces" which would be my perspective. Or you might not care. :). I'll add that the BD also takes up interior volume, air volume and although it's not much that body size just got smaller in terms of it's ability to move air and project.....

Lastly we have removed them several times on guitars that someone installed them on that did not need them and some bridge rotation again is not only acceptable it's desirable.
Author:  bluescreek [ Mon Jun 07, 2021 5:30 am ]
Post subject:  Re: Bridge Doctor
As Hesh mentions I have pulled them then fixed the guitar , Bellies are part of guitars for sure. If this were a hondo or a krafter no sweat but an old martin or Gibson no
Author:  banjopicks [ Mon Jun 07, 2021 6:48 am ]
Post subject:  Re: Bridge Doctor
Funny this topic just showed up. I almost bought a 73 D35 listed for $1700. I couldn't get past the ridiculous amount of rotation and deformed top. Oddly the action was good with plenty of saddle and it didn't seem to have loose braces. I've never seen one with this much rotation and still played well.

Now that I said all that, it may be atopic of it's own. How woyou fix it, through the hole, top off or back off to repair it properly.
Author:  Tim Mullin [ Mon Jun 07, 2021 7:32 am ]
Post subject:  Re: Bridge Doctor
I think I’ve installed 2 of these, the last was at least 6 years ago. I’ve always seen them as a last-gasp effort to make a guitar playable, where extensive restoration really doesn’t make any sense. In one case, the bridge doctor was no help at all, in the other there was some improvement, but not nearly what was hoped. If you ask a lot of these things, you’ll likely be disappointed. On the other hand, they’re not very expensive and can easily go back on the shelf, waiting for the next patient on ventilator.


Sent from my iPad using Tapatalk
Author:  jfmckenna [ Mon Jun 07, 2021 9:28 am ]
Post subject:  Re: Bridge Doctor
banjopicks wrote:
Funny this topic just showed up. I almost bought a 73 D35 listed for $1700. I couldn't get past the ridiculous amount of rotation and deformed top. Oddly the action was good with plenty of saddle and it didn't seem to have loose braces. I've never seen one with this much rotation and still played well.

Now that I said all that, it may be atopic of it's own. How woyou fix it, through the hole, top off or back off to repair it properly.


I just did this job on an old Martin. The problem wasn't so much belly but rather cave in, in front of the bridge, but it was due to rotation and a cracked brace. The center fan brace was cracked which was fixed. But to flatten the top I made a wooden block caul which was arched and then made an exterior arched caul that spanned the width of the guitar body over the bridge area. Then I put some thick felt on the interior block caul, put it in a boiling pot of water for about 5 minutes and then quickly got it in place and used screws to clamp the interior and exterior cauls together. Left it sitting for a week and it worked like a charm. This was of course hide glue but my guess is it might still work with a bridge patch that was glued with AR glue as well.
Author:  Hesh [ Mon Jun 07, 2021 10:16 am ]
Post subject:  Re: Bridge Doctor
banjopicks wrote:
Funny this topic just showed up. I almost bought a 73 D35 listed for $1700. I couldn't get past the ridiculous amount of rotation and deformed top. Oddly the action was good with plenty of saddle and it didn't seem to have loose braces. I've never seen one with this much rotation and still played well.

Now that I said all that, it may be atopic of it's own. How woyou fix it, through the hole, top off or back off to repair it properly.


Hey Sarge! You may not need to again belly is not a bad thing. What I would suggest is that you do precise measurements of the saddle position a 73 Martin D35 is suspect for having the saddle/bridge in the wrong position. Many Martins were made this way before they discovered the jig was off and they stopped using it. People who only play cowboy chords rarely notice it but if you're Steve Howe and you use the entire neck it will drive you insane. :) It did me :)

Regarding how you DO fix things like replacing a bridge plate or loose brace, etc it's all through the sound hole. We use child labor with little tiny arms and are sure to pay them $15 an hour because we are Liberals. :) Seriously we do it all though the sound hole. Taking a back or top or fret board off a guitar is a very, very rare thing that may only happen in shops where someone is into full on restorations and has the time to devote to them. Not us, next. :)
Author:  Hesh [ Mon Jun 07, 2021 10:23 am ]
Post subject:  Re: Bridge Doctor
When a client comes in and says "look" when we ask what's wrong with their guitar and they point to something I say "what" and they say "look" again and I don't see anything and say "what" again and then they tell me that there is a scratch there. I glance at Dave, he rolls his eyes....

That's when Blind Mellon Hesh here always feels like grabbing my big arse screw driver and making a 6" long, deep scratch on the front of their guitar and then saying "great, now that that's out of the way you can learn to actually play the thing...."

Of course I don't actually do this, I care for guitars (and at times the people holding them too...) but belly is like that scratch. It is what it is and in no way will it usually impact the instrument as a bad thing unless there are internal, structural reasons for the belly AND the belly is pretty severe. Again it has to be pretty severe and actually shortening the scale length to be an intonation issue.

Consider it like marriage (I'm single...) when we marry someone they look like this and then after 20 years they look like that.... But we still love them anyway and hope that they never find out about the significant other on the side. :)
Author:  banjopicks [ Mon Jun 07, 2021 11:27 am ]
Post subject:  Re: Bridge Doctor
Thanks guys. Had that guitar sounded like I expect an older Martin to sound, I probably would have bought and attempted to repair it. It was just meh, as the cool kids today say.
Author:  peter.coombe [ Mon Jun 07, 2021 7:23 pm ]
Post subject:  Re: Bridge Doctor
I have installed 3 and both were last gasp attempts to prevent inexpensive guitars from going to land fill. They worked. Customers were very happy, so I am happy. It is all very well to be purist and never use one, but sometimes it can be justified, and in at least one of my cases the owner told me the guitar sounded better.
Author:  Hesh [ Tue Jun 08, 2021 3:49 am ]
Post subject:  Re: Bridge Doctor
peter.coombe wrote:
I have installed 3 and both were last gasp attempts to prevent inexpensive guitars from going to land fill. They worked. Customers were very happy, so I am happy. It is all very well to be purist and never use one, but sometimes it can be justified, and in at least one of my cases the owner told me the guitar sounded better.


Glad that they worked out for you and there are applications and circumstances that they may be appropriate.

But... I will push back over the use of the term purist. We don't not push or recommend or even install bridge doctors because we are purists. We don't use them because in our world where we bill over $100 an hour with a one hour minimum and a 6 month waiting list for some jobs..... it does not make economic sense to be installing them in an instrument that our labor costs more than the instrument is worth. Or, in other words our clients don't even ask us to get involved with something like this because cost vs. benefit for them AND us is not present.

So to be clear it's not about not using a bridge Doc because I'm looking down my nose at it. It's our experience and opinion that they are largely not necessary, they have draw backs for a quality instrument that tone is a consideration and more if you read on below for one additional justification.

Moving on I wanted to mention one more thing. When I learned to travis pick I developed a bad habit of resting my palm on the bridge pins making my hand in contact with the bridge area. That's a no no in the world of having a lush with overtones, responsive guitar unless you specifically are looking to mute the instrument to some degree.

What's the difference between my hand providing additional support for the top and bridge by being in contact with it and having a big arse, honking hunk of wood inside the instrument doing the same thing..... That was a rhetorical question.
Author:  jfmckenna [ Tue Jun 08, 2021 9:46 am ]
Post subject:  Re: Bridge Doctor
I just remembered something about the BD's. I never tried this but I did read once one repairman who used them said that you have to fuss with the amount of tension on the BD lever arm (for lack of a better word) to dial in the guitar for better tone too. So for those who want to use one that might be something to consider trying.
Author:  Mike OMelia [ Tue Jun 08, 2021 4:20 pm ]
Post subject:  Re: Bridge Doctor
Well, did not mean to start a fire. I can’t prove it, but it seems to me that a a year of it in place will somewhat restore the bridge angle. Easy enough to remove after that. Sort of like an arm cast?
Author:  Chris Pile [ Tue Jun 08, 2021 4:39 pm ]
Post subject:  Re: Bridge Doctor
Viable concept, Mike. Now we need a proof of concept test...
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