Results 1 to 24 of 24

Thread: crack in top, F model

  1. #1
    Registered User
    Join Date
    Oct 2007
    Location
    Davison Mich.
    Posts
    382

    Default crack in top, F model

    as posted , I have an issue. not sure why, it is about 10 years old. I would like some info on where to find repair vids. I know this really isn't for beginners, but this is #3 of 4 F's that I have built so would like to see the steps involved to see if I can do it. the crack is about 3 in. long, behind bridge leading towards tailblock thank you
    Mike Marrs

  2. #2
    Lurkist dhergert's Avatar
    Join Date
    Jul 2012
    Location
    Blue Zone, California
    Posts
    1,175
    Blog Entries
    1

    Default Re: crack in top, F model

    Hmmm... Sounds like a center-seam separation. Is the crack relatively straight and relatively centered on the top as it travels from the bridge to the tailblock area?
    -- Don

    "It is a lot more fun to make music than it is to argue about it."

    2002 Gibson F-9
    2016 MK LFSTB
    1975 Suzuki taterbug
    (plus a large assortment of banjos, dobros, guitars, basses and other noisemakers)
    [About how I tune my mandolins]
    [7/29/2019 -- New Arrival!!!]

  3. #3

    Default Re: crack in top, F model

    I've been a follower of The Rosa Stringworks Workshop for a while now on YouTube. There are many crack repair videos, but they might be in videos titled by instrument, like Kentucky with issues, or j 45 from across the pond. But watching them is an education in what one guy does when it comes to repair. He usually does an evaluation towards the beginning, so you can fast forward to your issue or try another video.

    I recently glued a crack in the headstock of a banjo and had trouble finding a headstock repair as minor as what I had. Plenty were busted off completely.
    Silverangel A
    Arches F style kit
    1913 Gibson A-1

  4. #4
    Registered User
    Join Date
    Oct 2007
    Location
    Davison Mich.
    Posts
    382

    Default Re: crack in top, F model

    it is not the seam , but a bit to the right. I thought it was a scratch from changing a string, as it is straight, then as it gets to the bottom, it has a little wiggle to the right. it is sunburst , so the wiggle is in the dark spot, so I took a magnifiying glass, and can see the grain has a slight wiggle at the same spot

  5. The following members say thank you to Martian for this post:


  6. #5
    Teacher, luthier
    Join Date
    Oct 2017
    Location
    Southeast Tennessee
    Posts
    1,192

    Default Re: crack in top, F model

    If it is a closed crack, brew up some hot hide glue and rub it in with your fingers while you are flexing the crack.

    If possible, clamp it level with 2 violin clamps designed to be used through the f-hole, and a flexible clamping caul. Put some waxed paper between the caul and the crack so you don't glue the caul to the top.

    If it is an open crack, glue in a splint with hide glue. Let it project above the top and carefully trim it flush after the glue has cured.

    If you like, you can install a couple of very small cleats using the same f-hole clamps.

  7. The following members say thank you to rcc56 for this post:

    gtani7 

  8. #6
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    2,484

    Default Re: crack in top, F model

    Picture is worth 1000 words...
    The first thing I always do is investigate WHY the crack appeared and decide upon solution from there. If it is humidity crack you need to consider rehumidifying whole instrument before proceeding if it is structural (weak area of top etc...) you need to consider strengthening of the area etc.
    Adrian

  9. The Following 2 Users Say Thank You to HoGo For This Useful Post:


  10. #7

    Default Re: crack in top, F model

    If it is humidity crack you need to consider rehumidifying whole instrument before proceeding
    Why do repairman usually say to humidify first? It seems like if you humidify first it closes the crack making it hard to get glue into it. It would seem better to glue the crack first then humidify.

  11. #8

    Default Re: crack in top, F model

    Quote Originally Posted by CarlM View Post
    Why do repairman usually say to humidify first? It seems like if you humidify first it closes the crack making it hard to get glue into it. It would seem better to glue the crack first then humidify.
    Believe it or not, sometimes the wood cannot be clamped and glued flush without leaving a gap, if you don't humidify first.

    This summer I was working on a bellied-top on an acoustic guitar that pulled the braces away from the top by 5/8 of an inch -- in this case clamping would have broken the braces and/or the top to get them flush. So, I humidified the inside of the guitar with a damp sponge in a plastic cup -- it took 6 weeks -- adding moisture to the sponge from time to time -- the top flattened to where the braces could be clamped and glued successfully.

    I consider humidifying a repair technique, sometimes correcting years of neglect.

  12. #9

    Default Re: crack in top, F model

    I don't understand how humidifying would flatten a top. In my mind it would be the other way around. Are the sides expanding to make this happen?
    Richard Hutchings

  13. #10
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    2,484

    Default Re: crack in top, F model

    Quote Originally Posted by Dick Hutchings View Post
    I don't understand how humidifying would flatten a top. In my mind it would be the other way around. Are the sides expanding to make this happen?
    Guitar top would cave-in badly with too low humidity (because the top is shrinking more across than the bracing along its grain) and ultimately crack. rehumidifying would put the top back into flat shape.
    There was a nice vid by Taylor on YT showing what low RH can do to guitar.
    Adrian

  14. The following members say thank you to HoGo for this post:

    gtani7 

  15. #11

    Default Re: crack in top, F model

    Now that I know you're talking about a cave in top it makes sense.

  16. #12
    Registered User
    Join Date
    Oct 2007
    Location
    Davison Mich.
    Posts
    382

    Default Re: crack in top, F model

    I will try to get a picture of the crack tonight. I guess , I thought , I would have to take the back off to get at the front

  17. #13

    Default Re: crack in top, F model

    Without seeing a picture, it sure sounds like the crack is following the grain. If it's not the center seam but close to it, it's less likely to be caused by stress unless it's carved way too thin. It sounds like you got a piece of wood that wasn't completely dried. Or the humidity it's in has varied widely. A 30% drop in humidity can open up cracks and joints in an instrument quite quickly. At any rate, rcc56 laid out your options very well.

  18. #14
    Registered User
    Join Date
    Oct 2007
    Location
    Davison Mich.
    Posts
    382

    Default Re: crack in top, F model

    should have pictures tonight. I have to go play right now, wife is trying to find the post picture icon

  19. #15
    Registered User
    Join Date
    Oct 2007
    Location
    Davison Mich.
    Posts
    382

    Default Re: crack in top, F model

    If at all possible, would like to repair without taking the back off.
    Click image for larger version. 

Name:	DB407731-94D2-41B9-801D-50885EF88CD6.png 
Views:	70 
Size:	628.1 KB 
ID:	180665
    Click image for larger version. 

Name:	9964DD62-7AF8-4AC4-8FA7-B1F99A083788.jpg 
Views:	82 
Size:	469.0 KB 
ID:	180666
    Click image for larger version. 

Name:	58DB8E68-D4D0-48F6-98A9-B0F00519410F.jpg 
Views:	76 
Size:	651.9 KB 
ID:	180667
    Mike Marrs

  20. #16
    Registered User
    Join Date
    Oct 2007
    Location
    Davison Mich.
    Posts
    382

    Default Re: crack in top, F model

    you will have to click to make larger, but if I run my fingernail over it , you can fee it pretty easily.was really hoping it was a string scratch. This year it is 10 years old

  21. #17
    Teacher, luthier
    Join Date
    Oct 2017
    Location
    Southeast Tennessee
    Posts
    1,192

    Default Re: crack in top, F model

    There is no need for a great deal of analysis on this one. This is a simple closed crack. I recommend one cleat in the center of the crack. A cleat 1/4" wide and .080" to .100" thick will be sufficient.

    You can probably get this one level with one f-hole clamp. Use something flexible for an outside caul and tack your cleat to the lower jaw of the clamp with tape or one drop of glue. If you work quickly, you can seal the crack and install the cleat in one operation.

    There is absolutely no reason to take the instrument apart.

    I recommend that you take the strings off the instrument now, even if you're not yet ready to start the repair.
    If you're afraid of hot hide glue, you can use Old Brown Glue [make sure the bottle is fresh], or Titebond Original [which will work, but will leave a more visible repair].

    Quote Originally Posted by rcc56 View Post
    If it is a closed crack, brew up some hot hide glue and rub it in with your fingers while you are flexing the crack.

    If possible, clamp it level with 2 violin clamps designed to be used through the f-hole, and a flexible clamping caul. Put some waxed paper between the caul and the crack so you don't glue the caul to the top.

    If it is an open crack, glue in a splint with hide glue. Let it project above the top and carefully trim it flush after the glue has cured.

    If you like, you can install a couple of very small cleats using the same f-hole clamps.

  22. #18
    Registered User jim simpson's Avatar
    Join Date
    Sep 2002
    Location
    Wheeling, WV
    Posts
    4,915

    Default Re: crack in top, F model

    I agree with rcc5's suggestion/method.

    I really like the f-holes on this mandolin, neat to see something different. Is this a custom build?
    Cabin Fever String Band, Bill Gorby and the Musical Mercenaries

  23. #19
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    2,484

    Default Re: crack in top, F model

    I would bring it to competent mandolin repairman and prefer regular hot hide glue for repair, I don't think you can get as good penetration with Titebond unless it is diluted (e.g. weakened).
    Good violin repairer could be good choice as well if he will agree to work through the f hole.
    I might consider even thin CA for this repair if the crack is level and closed. The CA would glue the crack (penetrates tight cracks easily) and seal the finish in one step so the repairer should know exactly what he's doing. If not used properly it can leave dark glue line or mess on the finish.
    Adrian

  24. #20
    Teacher, luthier
    Join Date
    Oct 2017
    Location
    Southeast Tennessee
    Posts
    1,192

    Default Re: crack in top, F model

    Just for the record: A while back, I had the opportunity to see an old Gibson guitar that I had repaired 10 or 15 years earlier. The old repairs included several cracks that I had repaired with CA glue. The glue had given loose on some of those cracks.

    As a result, I no longer use CA for crack repair.
    Last edited by rcc56; Oct-20-2019 at 6:12pm.

  25. #21
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    2,484

    Default Re: crack in top, F model

    Quote Originally Posted by rcc56 View Post
    Just for the record: A while back, I had the opportunity to see an old Gibson guitar that I had repaired 10 or 15 years earlier. The old repairs included several cracks that I had repaired with CA glue. The glue had given loose on some of those cracks.

    As a result, I no longer use CA for crack repair.
    I'm huge proponent of HHG for wood joints of musical instruments (over Titebond and such) but in some cases there are other choices that are similarly effective.
    There are many varieties of CA and gluing softwood with thin CA is tricky. I've glued widely opened loose joint between back and body block on my first mandolin almost 20 years ago just squirting in some CA and clamping without any prior cleaning (I used white glue to assemble the mandolin and probably the glue was not good) and it has held since then. No sign of movement, not even a finish crack that commonly appears in the area, and that mandolin has become my beater (or my kids' beater) so it is not cared as gently as it deserves.
    Many of my jigs or shop fixtures were made using mostly CA and thay have held for two decades now again thay tok lots of beating and banging around being used.
    CA is pretty good stuff (with some limitations) if carefully used. I think you cannot blame opened old cracks to glue alone, Often the cracks open again and again in some tops that are structurally weak no matter what glue you use. The crack in OP's mandolin looks like either humidity crack or perhaps one caused by fall of mandolin on the tail end (but that requires closer examination). In such cases the cracks are not likely to re-appear if the mandolin is not neglected again.
    Adrian

  26. #22
    Registered User
    Join Date
    Oct 2007
    Location
    Davison Mich.
    Posts
    382

    Default Re: crack in top, F model

    Quote Originally Posted by jim simpson View Post
    I agree with rcc5's suggestion/method.

    I really like the f-holes on this mandolin, neat to see something different. Is this a custom build?
    yes this is one I built some time back
    Mike Marrs

  27. The following members say thank you to Martian for this post:


  28. #23
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    2,484

    Default Re: crack in top, F model

    I reread the OP and he asked about instruction...
    There are always frets.com and I would suggest looking for violin repair vids for cracks but you have to forget the comfort of having the plate off the instrument for repairs. One of the best resources is triangle strings with tons of great tutorials on their web.
    Adrian

  29. #24
    Registered User
    Join Date
    Oct 2007
    Location
    Davison Mich.
    Posts
    382

    Default Re: crack in top, F model

    found a violin shop near me that specialize in repair and restoration, . I do not have the clamps, or the experience, so I think I am going to visit him today, thanks for everybodys input

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •