Official Luthiers Forum!

When I tap my top (as you would during tap tuning), I get a rattling noise as if a brace is loose or something is not glued down. This is a cedar classical top, and all the cedar braces are glued on.

Do I throw it away and start over or is there a solution??

Thanks

_________________
Guitars...One's too many...Twenty is not enough.

Doug,

Throwing it away doesn't sound the way to go. It very likely is that one of the braces isn't fully glued down and it's a question of tracking down where the rattling is coming from. Sometimes I have done this by holding on to the top by each indiviual brace (in lots' of positions) until I find a spot where the rattle stops and look further.

Also if there is a split somewhere in the top you will get a rattle.

I suspect it's a matter of patience in tracking down the culprit, and then working out the appropriate fix.

Good luck hunting!Dave White38823.6961226852

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

I assume it is not glued onto the box.

My guess is a brace is loose or the top has a crack. If you can find it you can fix it. If you can't find it cook some salmon on it. I hear it is really good....

_________________
Joe Beaver
Maker of Sawdust

Doug I had the same problem with a brace on the back of my most resent build I isolated it by lightly taping along the braces one by one and listening closely. when I came to the problem brace there was a dead tap and small rattle. It was in the cross strut or main spar of my star braced back on the left side. Once I knew where it was I got the inspection mirror in with a light to help see. I found that from the taper to about half way to the center seam had come loose. I cleaned the separation best I could and laid some titebond on a long .005" feeler gauge using the inspection mirror I inserted glue into the separation and took two brace jacks and tighten the jacks over each end of the separation and allowed to dry over night. The next day all was well.

If the separation or cracked brace is on the top it is more difficult to repair but can be done. On tops it is easier to remove the top to repair the brace. If the guitar is not bound yet This is the best rout. Plus learning to separate a top is good experience

Doug,

Another way to check for a loose brace is by using a tuning fork (in you have one handy). If you happen to have a loose joint, you will find out immediately due to the difference in vibration.

A long shot but not as stupid as it sounds.....did you pull out the bridge
caul after gluing down the bridge? Im assuming the top is on the guitar
and the bridge is on of course. This has happened to a few luthier
friends.

Cheers Martin

Doug, I have had this happen on the upper braces (not the fan braces) I leave these longer than needed and soemtimes they don't get glued down all the way to the very edge or sometimes they overhang the soundboard completely thus buzzing when tapping if they don;t get glue all the way to the edge.

Well, I found the problem area. It was the joint for bottom V brace. It had come apart. I flexed the top and shot some CA glue into it. Problem solved. I am amazed at how loud the rattle was for such a small joint.

Thanks!

_________________
Guitars...One's too many...Twenty is not enough.