The Acoustic Guitar Forum

Go Back   The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Build and Repair

Reply
 
Thread Tools
  #1  
Old 11-07-2017, 12:26 PM
rodmbds rodmbds is offline
Registered User
 
Join Date: Sep 2012
Location: Brazil
Posts: 312
Default Can tailpiece sink a guitar's top?

Hi everybody! Before I start I'd like to thank you all for the help you gave me on another thread, about repairing a chip / crack.

This time, another project. I got this guitar on a major bargain. The previous owner sold it to me as a "broken" or "beyond any repair" guitar, while all it had was in fact a loose bridge.

It is the classic example when someone puts steel strings on a nylon guitar. After the bridge came off, he tried using two screws to fix the bridge. All it did was to crack the bridge a little and leave the top with two screw holes.

Anyway, I talked to a friend who's a luthier and he advised me to reglue the bridge and explained me all the process. He said the bridge couldn't be saved and I should get a new one. Thing is, this is an old model, called the factory here and their bridges are now in a slight different size.

But my original idea was, to be cost effective, to reglue the bridge itself, using wood glue and later wood filler. Then, glue the bridge back to the top, clamp it etc. But then use a tailpiece as a way to "spare" the bridge from more damage and tension.

Having said that, here's my question: this friend of mine who's a luthier told me I could do that, but using the tailpiece would cause the top to sink over time, years maybe. That's why I'm here cause I don't want to simply say, "are you sure?" to him cause I know what the answer will be. The guitar is nylon strung and I guess he is giving advice about a steel string.

If so, isn't there a way I could reinforce the top the prevent this from happening?

Thanks a lot for any help. I'll be posting pictures as soon as I can.
Reply With Quote
  #2  
Old 11-07-2017, 12:51 PM
Alan Carruth Alan Carruth is offline
Registered User
 
Join Date: Feb 2011
Posts: 2,929
Default

The devil, they say, is in the details.

First; a cracked bridge is usually not worth trying to save. The stresses on the piece are high, and often cause the cracks in the first place. It's hard to make a glue joint that will outlast solid wood in a case like this. Granted, the damage this time was partly from the poor repair, but the bridge is still cracked, and still highly stressed.

Classical bridges tend to be pretty similar, but vary somewhat in size from maker to maker, and even from time to time on guitars from the same maker. Since this is a factory guitar putting on a bridge of a slightly different size probably won't devalue it to speak of. Again, a lot depends on details we don't have.

A tailpiece does put a downward force on the top, and that will eventually cause it to dish inward. Your luthier friend is right. How 'eventually' depends on the details of the case, and we can't speak to those.

One thing that makes a difference is your purpose in doing the repair. Another is the value of the guitar. If it's a valuable guitar then you should probably try to put it back to 'original' condition if possible. If you're trying to learn the right ways to do repairs, then you'll learn more that way than from a simple jury-rig. If the objective is to put a cheap beater guitar on the road for another few years, then a tailpiece could well be the best way. It's possible that the original bridge might even hold up for a while in that scenario, but I would not bet on it.
Reply With Quote
  #3  
Old 11-07-2017, 07:01 PM
Ned Milburn Ned Milburn is offline
Registered User
 
Join Date: Feb 2011
Location: Dartmouth, NS
Posts: 3,125
Default

Okay, my 2 cents...

Take the idea of a tailpiece and toss it into the trash bin.

Classical bridges tend to be MUCH more standard than steel string bridges. Either make a bridge yourself, or buy one with a footprint equalling or greater than the present bridge size. MAKE CERTAIN when gluing the new bridge that the saddle slot is positioned properly, or else you WILL have intonation troubles.

Make a new saddle. String it. Play it.

Done.
__________________
----

Ned Milburn
NSDCC Master Artisan
Dartmouth, Nova Scotia
Reply With Quote
  #4  
Old 11-08-2017, 08:19 AM
Truckjohn Truckjohn is offline
Registered User
 
Join Date: Feb 2016
Posts: 1,305
Default

What is your goal here? Do you want to run steel strings or nylon strings?

Do you just want to end up with a (mostly) playable beater or are you trying to turn it around for sale?
Reply With Quote
  #5  
Old 11-08-2017, 07:30 PM
printer2 printer2 is offline
Registered User
 
Join Date: Dec 2012
Posts: 3,752
Default

I am with Ned. EBay for $2.50 - $25.00

https://www.ebay.ca/itm/6-String-Bri...gAAOSwZJBX~0cB

https://www.ebay.ca/itm/007-4691-000...EAAOSw1DtXDnNs
__________________
Fred
Reply With Quote
  #6  
Old 11-12-2017, 05:51 PM
rodmbds rodmbds is offline
Registered User
 
Join Date: Sep 2012
Location: Brazil
Posts: 312
Default

Hi, thanks for the replies and sorry for the delay in answering.

I've chosen to get a new bridge and reglue it, as you guys said. The tailpiece will be a Plan B in case the repair doesn't come out as expected.

Anyway, while searching about this, many people mentioned the Kris Barnett's guitars:

http://www.krisbarnettguitars.com/

I wrote an email to him inquiring about the tailpiece and the sunken top, here's what he answered me:

"The tailpiece actually relieves a lot of pressure from the soundboard by nearly eliminating the shear and rotational forces caused by the tension of the strings. Because of this, you can actually make the bridge lighter and much smaller than a traditional bridge as it does not need such a large gluing surface.

The downward force caused from the break angle of the strings is no different than a traditional instrument and so will not cause any damage to the soundboard. This force is actually quite minimal compared to the other forces being enacted on the bridge in a "traditional" configuration. Overall, the longevity of the soundboard could be much improved with the tailpiece configuration.

The difficult part with the tailpiece is getting the setup correct so that the break angle of the strings is correct and the overall geometry of the strings, soundboard, and bridge remains in tact. If you try using a tailpiece with a standard bridge, the strings will likely be touching the soundboard after they leave the tie block which will cause sympathetic vibration and unwanted rattling or other noises. "

So there we go. Thought it would be nice to share it and maybe help somebody with the same question in the future.

Thanks again and I hope the repair goes alright.
Reply With Quote
  #7  
Old 11-13-2017, 08:58 AM
Truckjohn Truckjohn is offline
Registered User
 
Join Date: Feb 2016
Posts: 1,305
Default

I have built several guitars of each style...

His semi-stated assumption which needs to be made explicit is that you have a bridge design which routes the strings over the saddle, down into the bridge, and then straight out the back of the bridge to the tailpiece.

And if you are going to do that - Proceed - the information he gave you is useful for that specific case....

But that's not how people typically do it... They usually just go up over the bridge to the tailpiece... In this case - there is significant down force on the bridge - which causes the top to "sink".....

A "typical" pin or string-thru bridge anchors the strings to the soundboard. This results in a significant "up" force on the bridge - which causes the typical top rise we are used to seeing....

That's what you see generally... A floating bridge pushes the top "down" and a fixed pin bridge pulls the top "up".....
Reply With Quote
  #8  
Old 11-13-2017, 09:40 AM
LouieAtienza LouieAtienza is offline
Registered User
 
Join Date: Feb 2013
Posts: 4,621
Default

Cory Batson is one builder I know that uses a tailpiece in conjunction with a string-through bridge. Jeff Babicz uses a separate piece behind the bridge for string angle, and anchors the strings to the top itself, along the rim. Randy Muth also had models that utilized a flat top with a tailpiece, as well as Martin Keith. It should be noted that these builders have designed their tops accordingly.
Reply With Quote
Reply

  The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Build and Repair

Tags
bridge, crack, loose, tailpiece

Thread Tools



All times are GMT -6. The time now is 01:10 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2000 - 2018, The Acoustic Guitar Forum
vB Ad Management by =RedTyger=