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 Post subject: washburn bridge reglue
PostPosted: Sat May 06, 2017 11:48 am 
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Cocobolo
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I easily removed the loose bridge & there is 1/8 to 3/16 lacquer around the perimeter of the bridge
A fair bit of the spruce has ripped away.
Do remover the lacquer.
If/when I sand the top there will be a lot of rough pits in the spruce.
Do I ignore or fill.
Do I leave some of the spruce on the bridge?
What glue recommendations?

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PostPosted: Sat May 06, 2017 11:55 am 
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Old Growth Brazilian Rosewood
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Mike I did a search on "bridge reglue" and here is a link to the results. You'll have to click and read a bit on your own but there are many good posts from numerous forum members in the various threads answering all of your questions.

Good luck.

http://luthiersforum.com/forum/search.php?keywords=%22bridge+reglue%22&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search


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PostPosted: Sat May 06, 2017 2:25 pm 
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Cocobolo
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thank you Mr. Hesh. That helps a lot but one think I couldn't find is if there are chips out of the top should I do anything like fill them?

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PostPosted: Sat May 06, 2017 3:17 pm 
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mikemcnerney wrote:
thank you Mr. Hesh. That helps a lot but one think I couldn't find is if there are chips out of the top should I do anything like fill them?


Yes, if you can remove the chips/tearout cleanly form the bridge, glue them back with HHG.


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PostPosted: Sun May 07, 2017 11:30 am 
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Old Growth Brazilian Rosewood
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Hi Mike, you are very welcome.

As our friend Greg said if we can slice off the fibers/chips on the bridge bottom gluing them back down to maximize wood-to-wood gluing surface is a good idea. I would not however fill any voids with anything other than spruce or what ever the top is made of.

You noticed how lousy f*ctories are at clearing the gluing surface under the bridge. That 1/8" to 3/16th" when you add it all up around the bridge perimeter adds up to a decent percentage of additional gluing area. As such I would clear that back too but stay short of the actual bridge perimeter.

We have a jig that Dave made that lets us clear finish to only about .008" or so of the bridge perimeter. That's not necessary though but you can see how important maximizing wood-to-wood gluing surface is if we would go to these lengths. The link I posted also has some threads with the various jigs some of us have made for this purpose.

Lastly bridges lift for a reason. From worn bridge plate pin holes that start to form an unlevel top surface as they "crease" the bridge plate to lousy technique and not clearing back enough finish at the f*ctory we try to be sure we are not just fixing a symptom and not the root cause. Dryness can cause a bridge to lift as well.

And really lastly some food for thought. You know that 1/8" to 3/16th" of finish that you noticed? If you measured the thickness of the finish too you might find that it's thick enough to negate any wood-to-wood contact for some distance inward as well as the bridge has to span this gap and of course the exposed wood is not in contact with it for some distance inward as we clamp the bridge down. This is one of the major reasons why bridges lift, thick finish, lack of clearing finish inward and all this can add up to leaving upwards of 40% of potential gluing surface on the table by some f*ctories.


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PostPosted: Sun May 07, 2017 12:30 pm 
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Thanks.
OK you don't like filler i presume glue doesn't stick to it. I probably saw it somewhere but can't find it now.
What re your first 2 choices of glue.
thanks

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PostPosted: Sun May 07, 2017 2:02 pm 
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Old Growth Brazilian Rosewood
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mikemcnerney wrote:
Thanks.
OK you don't like filler i presume glue doesn't stick to it. I probably saw it somewhere but can't find it now.
What re your first 2 choices of glue.
thanks


My first choice is HHG but that's if the surfaces are well prepared and no gap filling is required. HHG also has some requirements that if ignored will bite us. Very short open time, preheating, etc all matter. If not experienced with HHG and you just want to get this done Titebond original is fine too.

Titebond has lots more open time and for something like this is fine.

In rare situations where the top is all torn up and the guitar is a POS anyway.... ep*xy can be an alternative.

We do lots of Martin warranty work and go overboard on our bridge reglues because we always want to do great work. HHG, clearing the finish back to .008" of the bridge perimeter and rabbiting the bridge bottom to fit the "pocket" we made in the finish is standard fare for us with bridge reglues.

But on occasion alternatives can be "appropriate for the instrument..." ;)


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PostPosted: Sun May 07, 2017 2:07 pm 
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Old Growth Brazilian Rosewood
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mikemcnerney wrote:
Thanks.
OK you don't like filler i presume glue doesn't stick to it. I probably saw it somewhere but can't find it now.
What re your first 2 choices of glue.
thanks


One more tip, within 15 minutes of the actual gluing and clamping lightly scrape the bridge bottom with a single edge razor blade.

Actually two more tips. Some folks will clamp the hell out of a flat bridge on the domed guitar top. Not being critical we just do this differently.

We want only light finger tip pressure to hold the bridge down in all areas including the wings. We clamp it well anyway but don't want the glue to have it's first mission of warping a thick bridge to the top's shape or vice versa. This means scraping and sanding a bit of the dome's shape into the bridge bottom. Know your belt sander platen...;) BTW HHG really benefits from very well fitted parts so shaping the bridge bottom when using HHG although not required we think adds to the "system" that we use.


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PostPosted: Sun May 07, 2017 9:00 pm 
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I'm guessing the scrape on the bridge is about exposing a few new unozidized molecules on the surface.
I built a uke a year ago & bound it with lignum vitae, which is just about the 'waxiest' wood i've ever seen, sanded again after fitted & glued. Still good today. I'll let you know in 15 years how it's holding up
I've done a lot of veneer work with titebond original extend & according to Darryl over at the veener forum in his testing it is a rigid glue line almost equal to urea
(unibond). I think that's what i'm going with. I'm going to call franklin ( who i've always got knowledgeable customer support) tomorrow, & ask them if it sticks to any fillers. You are a big help thanks.

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These users thanked the author mikemcnerney for the post: Hesh (Mon May 08, 2017 2:46 pm)
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PostPosted: Mon May 08, 2017 9:55 am 
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Veneer is not guitar bridges.....

Titebond I, HHG, and fish glue are probably the most polular for gluing wood to wood followed by CA and epoxy for gluing a bridge straight on top of certain epoxy/poly finishes.

I will pile on Hesh's suggestion to ensure the bottom of the bridge matches the curvature of the top before gluing it down.... I really dont like the idea of the bridge wings pulling back up because of trying to glue a nice stiff flat rosewood bridge onto a curved top.....



These users thanked the author truckjohn for the post: Hesh (Mon May 08, 2017 2:46 pm)
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PostPosted: Mon May 08, 2017 10:12 am 
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Cocobolo
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I am definitely going to do my best to match the curvature. I just noticed this morning that the washburn has one heck of a domed top unless some of that is big time distortion. I am considering a bridge doctor too/ Any thoughts on that?

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PostPosted: Mon May 08, 2017 2:58 pm 
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Old Growth Brazilian Rosewood
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Mike right you are, scraping is preferred to sanding because on a microscopic level sanding leaves debris where scraping tends not to. All Carruth is who taught me about scraping less than 15 minutes before gluing and that it contributed positively to "joint energy" IIRC. That was a long time ago here and something that I read in passing so I apologize in advance if I am unintentionally misrepresenting anything that Al said. If not here's another thanks to Al!

Lastly remember too that bridge glue joints need to be "serviceable" and that means a known known..... glue that releases with heat and/or steam. That's why John is spot on with his comments above too.

And really lastly be sure to carefully inspect the inside of the box. Major distortion may have a reason. Also check out the bridge pin holes in the bridge plate. They tend to enlarge over time as our cheap-arse genuine imitation pl*stic, slotted bridge pins permit the string balls to migrate upward damaging the bridge plate, top and often causing bridges to lift. Loose braces lead to distortion in the top too.

Regarding bridge Doctors I'm sure they have their place but... my preference is to investigate and repair all other contributing factors as mentioned above before I would consider going that route. There is also the notion of what's appropriate for the instrument.


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PostPosted: Mon May 08, 2017 7:28 pm 
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Koa
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What sort of washburn is this? Washburn has been around for over 100 years now.... Quite a few old guitars out there from "history"....


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PostPosted: Tue May 09, 2017 8:08 am 
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J2004swltd
There were 288 made to be sold in Canada only?
I guess I've decided to inlay some spruce in 2 -.400 diameter chip outs

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PostPosted: Wed May 10, 2017 9:43 am 
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I don't normally match the curvature of a the top to a bridge and I've never had a repair go out that came back in either. So there's that ;)

Even if the top is bellied and warped one could argue that gluing a flat bridge down would be better as it helps to keep that area flat. The bridge is a brace after all. But in some cases like that I have matched the curve. It just depends. One thing you should definitely do is make a caul for the inside that fits over the bridge plate and if you are going to curve the bridge then curve the caul. Screws with wing nuts and lock washers make excellent clamps for the center point of the bridge through the pin holes. If you have to force the wings down then you have problems but if finger pressure is good enough then...

Just throwing out some alternative facts about guitar repair :)

IMHO bridge doctors are terrible. The definitely do work as advertised. They will indeed force the belly straight but I think you will notice a drastic difference in tone. I guess in some cases that could be a good thing.

Do you have pics that show the bellied top?


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