View Full Version : Crack in the back
Will Little
Jul-05-2004, 1:47pm
I have a crack in the back of my mando, an epi mm50 f style.
It's not terribly deep, but it's only getting worse.
Are there any solutions for a repair, or at least something to stop the damage from worsening?
Luthier Vandross
Jul-05-2004, 4:46pm
Yeah, glued up, and clamped... or... have to see it to know.
M
fatt-dad
Jul-05-2004, 6:04pm
Warning - I am not a luthier.
I have heard of taking a piece of brown paper bag, parchment, canvass, etc. dipping it in watered down glue (i.e., elmers) and then "papering" the crack. This would only work if you could get to it from the inside. If you did this (and if you had some real verification that I am not too far off), then you could take some masking tape on the outside, place some on either side of the crack and then rub some glue into the crack (let the paper on the inside dry first). With the crack infilled from the outside (and the glue set) you then remove the masking tape and then remove any glue that rises up above the crack.
Well, I am going from some things I think I heard, may have even made some of it up. I did try the glue rubbed from the outside once and it worked.
Good luck.
fatt-dad
Will Little
Jul-05-2004, 6:39pm
http://home.earthlink.net/~wfl2/mando1.jpg
http://home.earthlink.net/~wfl2/mando2.jpg
Luthier Vandross
Jul-07-2004, 3:43pm
2 bothers.. I need to see inside, with a mirror, look at the neck block in there... what's that like? should be solid, and not cracked off in that area.. right...
Hmm I wonder... does that not follow the grain... exactly?
If it's nice inside, and the crack is as it appears.. a sliver of finish, with a fissure leading down into the treble side, away from the back join.. then it's probably some glue, a clamp, and a touch of french polish. If the block has anything going on, it needs to be opened up with a japanese saw... you cut the back off at the binding... and then...
M
Will Little
Jul-09-2004, 12:01pm
Glue and a clamp did the trick.
And getting a humidifier to prevent the problem from happening again!
Thanks for your help everyone, my mando is healthy again.
I would think a back crack is more serious than a front crack since the front does not structually support the mando.
Luthier Vandross
Jul-09-2004, 4:58pm
More serious... maybe. Generally, I have seen catastrophic faliures in the lower tops, and forward backs, barring top caves. The ribs/neck blocks are the most common though.
That crack looks like an atypical crack, and I wonder if the wood may have had a separation there during the build, just kind of waiting to happen. According to the visible grain, it looks feathered, but if you have it nice an sealed, she's fine!
Miles
Michael Lewis
Jul-09-2004, 10:59pm
Tom C, is that comment bait? Of course the top supports LOTS of stress. It is under compression from both ends and from the bridge. Considering how thin it is relative to other stress loaded parts of the structure it is a wonder that most tops stand up to the punishment they are dealt. There is much less stress in the back. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/wink.gif