|
|
Joined:
October 2012
Posts: 1034
Location: Yokohama, Japan | I'm sorry about the double post! My session seems to have timed out! Here's another try... I needed some advice on how to go about repairing a 1117-4 (apparently 1973 vintage). I posted here previously in search of a luthier in Virginia Beach, but had no luck finding anybody willing to work on this beautiful Ovation. With the Mother Ship gone, I really had no other choice, so the guitar is now in Japan with me, but I know there is no way I'm going to find anybody out here to work on this Ovation for me. It looks like I'm going to have to hack at this thing myself... 
As you can see, she's a beauty... 
The spruce top is rich with texture... 
the soundboard just glimers from top to bottom... 
I learned from DanSavage's "1619-4 Rebuild" that this 1117-4 probably has a hand laid fiberglass bowl! 
And it looks like somebody had to patch up this bowl some time in the past too... 
but the top is cracked just a bit (definitely can be glued back together)... 
and the bridge is peeling away from the body... 
the crack is going right down the center from the bridge to the bowl, but it is not that bad and certainly can be glued back into place... 
another angle shows a little chip in the spruce top... 
cracks around the bridge seem to indicate that the bridge is lifting together with the top coat right off of the wood... 
The finish seems to be peeling away together with the bridge...kinda scary! 
You can see the lifting more clearly here... 
and interestingly enough, no bridge plate! Is that possible? Could it have fallen off or something? I've built 4 electric guitars, but have no experience dealing with acoustics; and so, I know I'm going to have to take it slow and just be extremely careful to say the least. But I'm kind of not sure about the order in which to dissasemble and assemble the guitar. Here's what I had in mind... 1). Removing the bridge from body. The finish on this guitar seems quite brittle. I'm not sure if heat is the only thing I need to remove the bridge. Should I take an exacto knife and carefully cut the brittle finish around the bridge to ensure the finish doesn't peel away from the body some more? I know I'm not going to be able to maintain a pristine finish, but I do want to keep it as clean as possible. In the areas where the finish is peeling away from the body, should I glue the finish back into place with CA glue or should I just leave it as is? 2). Glueing the crack going down from the bridge to the bottom of the soundboard. For this, I wasn't sure how to get the glue into the crack without cracking the top further (I know a syringe is useful, but I'm not sure if that will be enough to keep secure the soundboard again), and so I was considering glueing a very thin and narrow piece of spruce right under the crack for the entire length of the crack under the soundboard to ensure the crack was fully secured. The other question I had was, should I add a bridge plate? I can tell this 1117-4 is super resonant, and I wasn't sure if a bridge plate was necessary, or if I should just leave it as is. 3). Glueing the bridge back on to the soundboard. Seems easy enough, but I was planning on using tite bond. My concern is if the bridge is peeling together with the finish, I'll actually be glueing the finish back onto the spruce soundboard, and I wasn't sure if that would hold. I suppose I could scrape off and sand any excess finish, but I have a feeling the tite bond will seep into any areas that need bonding further strengthening the adhesion of the bridge the soundboard and any of the finish that is peeling off around the bridge. Jeez I sure hope this is making sense. Sorry for rambling on, but if any of you have any other helpful insights I would really appreciate it. I'm not planning on getting started on this project anytime soon, but wanted to make sure I spent plenty of time getting help and thinking through the project carefully. Sure would appreciate hearing from you all! Thanks a bunch!
Edited by arumako 2014-06-29 12:42 PM
|
|
| |
|
Joined:
June 2012
Posts: 2317
Location: Pueblo West, CO | arumako - 2014-06-29 10:27 AM I learned from DanSavage's "1619-4 Rebuild" that this 1117-4 probably has a hand laid fiberglass bowl! And it looks like somebody had to patch up this bowl some time in the past too... but the top is cracked just a bit (definitely can be glued back together)... and the bridge is peeling away from the body... the crack is going right down the center from the bridge to the bowl, but it is not that bad and certainly can be glued back into place... another angle shows a little chip in the spruce top... cracks around the bridge seem to indicate that the bridge is lifting together with the top coat right off of the wood... The finish seems to be peeling away together with the bridge...kinda scary! You can see the lifting more clearly here... and interestingly enough, no bridge plate! Is that possible? Could it have fallen off or something? 1). Removing the bridge from body. The finish on this guitar seems quite brittle. I'm not sure if heat is the only thing I need to remove the bridge. Should I take an exacto knife and carefully cut the brittle finish around the bridge to ensure the finish doesn't peel away from the body some more? I know I'm not going to be able to maintain a pristine finish, but I do want to keep it as clean as possible. In the areas where the finish is peeling away from the body, should I glue the finish back into place with CA glue or should I just leave it as is? 2). Glueing the crack going down from the bridge to the bottom of the soundboard. For this, I wasn't sure how to get the glue into the crack without cracking the top further (I know a syringe is useful, but I'm not sure if that will be enough to keep secure the soundboard again), and so I was considering glueing a very thin and narrow piece of spruce right under the crack for the entire length of the crack under the soundboard to ensure the crack was fully secured. The other question I had was, should I add a bridge plate? I can tell this 1117-4 is super resonant, and I wasn't sure if a bridge plate was necessary, or if I should just leave it as is. 3). Glueing the bridge back on to the soundboard. Seems easy enough, but I was planning on using tite bond. My concern is if the bridge is peeling together with the finish, I'll actually be glueing the finish back onto the spruce soundboard, and I wasn't sure if that would hold. I suppose I could scrape off and sand any excess finish, but I have a feeling the tite bond will seep into any areas that need bonding further strengthening the adhesion of the bridge the soundboard and any of the finish that is peeling off around the bridge. Jeez I sure hope this is making sense. Sorry for rambling on, but if any of you have any other helpful insights I would really appreciate it. I'm not planning on getting started on this project anytime soon, but wanted to make sure I spent plenty of time getting help and thinking through the project carefully. Sure would appreciate hearing from you all! Thanks a bunch! Hi Arumako, Yep, that's definitely a hand-laid cloth bowl. It's the second generation bowl hand-laid in a female mold. The patch at the bottom of the bowl is a reinforcement put there by the factory to strengthen the bowl so the lower strap button molly doesn't pull through the FG bowl. Mine has the same thing and I've seen others that have the same thing. Not all of the bracing patterns had bridge plates. Neither of my CL A-braces have bridge plates, either. The early X-braces didn't use them, either. The later LX-brace patterns do use maple bridge plates. The bridge plate is only really necessary for guitars that use bridge pegs to hold the strings. This keeps the string balls from pulling through the spruce top. WRT your repairs: 1) The finish is either polyester resin or polyurathane. When I started my 1619 project, I tried to cut through the finish around the purfling with an Xacto knife and it was nigh on impossible. If you use thin CA you could wick it into the cracks and it will readhere the finish back to the wood. 2) If you put the split wood back together, you can wick thin CA into the crack and glue it that way. Thin CA has terrific capillary action and if you put enough, it should fill the entire split with glue. Unlike thicker glues, thin CA works best when the pieces to be glued are in their final position and let the capilllary action of the glue do its thing. I wouldn't add a bridge plate as it's only going to deaden the sound. 3) Do not use Titebond to glue the bridge back down. That's only going to cause more problems later on. Titebond is a PVA glue and as such will only start to creep. There are only two glues that will not creep when heated: hot hide glue and CA. Even epoxy will creep with enough heat. If you can pull the bridge out far enough you could use medium CA, such as Zap-A-Gap to glue the finish back to the wood. If you can pull the bridge away from the top, you can apply the glue, then squeeze and clamp it back down and let the CA dry for 24 hours. When you do this, glue should squeeze out of the cracks. Use acetone to clean it off the surface of the finish. It will dissolve the CA without harming the finish. Dan
Edited by DanSavage 2014-06-29 4:56 PM
|
|
| |
|
Joined:
October 2005
Posts: 4044
Location: Utah | I've read a lot of conflicting info on Titebond types of glue. Yes it creeps at lower temperatures than hide glue, but it still takes a fairly high temp. Certainly hotter than comfortable storage for the guitar. Titebond is removable with heat, as is hide glue, which make those two the better choices for the bridge rather than epoxy. Whichever glue you use, you should clean both surfaces to get good contact of the glue to wood. Old glue residue may be problematic, especially if you're using a different kind of glue than was there originally.
Liquid hide glue is an interesting product. Apparently the stuff in a bottle loses about 10% of strength due to the additives to keep it liquified at room temp. It should be strong enough to hold the bridge on. There are some references online for making liquid hide glue at home.
Bottom line is that the best glue would be fresh hot hide glue. Liquid hide glue or Titebond may be adequate. Some luthiers say it they will work just fine, others say they are the devil and to stay away from anything but hide glue. For a bridge which has all that stress on it I think I would bite the bullet and learn to use hot hide glue. This gives you the most options for future repairs or adjustments, too.
To remove the bridge look for some online youtube videos. It looks pretty straightforward, though I've not done it myself. I have an old wood box acoustic with a lifting and curling bridge which I may try to repair. You can use a hot iron to heat up the bridge and loosen the glue. And/or you can use a metal spatula heated up and then push it under the bridge to release the glue. |
|
| |
|
Joined:
October 2012
Posts: 1034
Location: Yokohama, Japan | Thanks for the advice DanSavage & FlySig. I really appreciate it. Japan gets really hot and humid in the summer, and so hide glue sounds like a good option, but I don't think I can get the stuff over here. I might have to experiment in making my own, but being my first attempt I'm a bit concerned about my capacity to work with adhesives like these.
If I use CA glue, do you think that I might be able to glue the bridge in place without removing it from the soundboard first? There seems to be plenty of space to apply CA, but I'm not so sure about the cleanliness of the area as the guitar has been out of use for several months or so...it doesn't look as though anybody attempted a glue job before me... |
|
| |
|
Joined:
June 2012
Posts: 2317
Location: Pueblo West, CO | I'm really surprised to hear that you can't get hide glue over in Japan since it's the oldest glue in the world and has been in use for, literally, thousands of years.
Yes. You can absolutely use CA to glue the bridge in place without removing the soundboard. I suggest going to your local hobby store and buying some CA and wood, then experimenting on scrap pieces so you can get a feel for what it's like to work with it. Get some thin and medium CA. Then try gluing the scrap pieces together.
If the bridge still has the finish stuck to the bottom and it's the finish that's separated from the top wood and you just want to glue the bridge down by re-attaching the finish to the top wood, then hide glue probably wouldn't be the best choice because it has poor adhesion to plastic. Hide glue works best on wood-to-wood joints.
As FlySig points out, the bridge has lots of stress holding the strings. So, your best option might be to completely separate the bridge from the finish, clean the facing wood surfaces, then get a good, clean joint with fresh glue. From the photos, it looks like your bridge is almost completely broken loose. So, you may as well pull it completely free and do the job right.
Once the bridge is free of the top wood, it will make gluing the split a lot easier. |
|
| |
|
Joined:
October 2012
Posts: 1034
Location: Yokohama, Japan | Thanks again DanSavage! So after some web research I found one webstore that sells hide glue (in Japanese its apparently called Niwaka Sechyakuzai and used mostly by furniture makers over here). I checked out Dan Erlewine's video about hide glue too. Haven't decided whether to use hide glue or CA, but I think I'll know better once I get the bridge off of the soundboard. So...first, remove the bridge and clean both the soundboard and the bridge. Second, seal the crack using CA glue and finally, if the bottom of the bridge is mostly polyester resin or polyurethane finish, then I'll go for the CA glue and if a lot of wood is showing I'll go with the hide glue. And yes, I'll make sure to work with some samples before I get started on the real thing just to make sure I have a feel for the adhesives. I think I'll get to this some time during the summer so wish me luck! Thanks again for the valuable advice! |
|
| |
|
Joined:
December 2003
Posts: 13987
Location: Upper Left USA | Very similar in construction as the 1615 I'm working (bowl and finish). It is amazing how well the CA glues at different viscosities can rework the finish.
It will be good to see this one back in the game! |
|
| |
|
Joined:
October 2005
Posts: 4044
Location: Utah | Was the bridge glued on top of the finish, or was the bridge glued to bare wood? |
|
| |
|
Joined:
October 2012
Posts: 1034
Location: Yokohama, Japan | Hi FlySig, thanks so much for helping out. When I peel the bridge up, I can clearly see that there are blocks of finish stuck to the bottom of the bridge and there are pieces of finish still stuck to the soundboard. Actually, when I push the bridge back into position, it almost feels like a piece of a puzzle like it kind of "clicks" into place. It looks like most of the finish is stuck to the bottom of the bridge with maybe approximately a quarter of the finish still on the soundboard and the rest stuck to the bottom of the bridge. So, the bridge was definitely glued onto the finish. I'm not sure if I should leave all the finish residue in place and glue the bridge back into position using CA glue, or if I should scrape the finish off of the bottom of the bridge and scrape the finish off of the bridge area on the soundboard and use hide glue. I am definitely leaning toward removing the entire bridge so that I can get a good clean repair on the soundboard crack. It's all kind of intimidating though!
Edited by arumako 2014-06-30 10:04 AM
|
|
| |
|
Joined:
June 2012
Posts: 2317
Location: Pueblo West, CO | IMO, having the bridge glued to the finish instead of bare wood is kind of a game-changer.
As you can tell, the finish is kind of thick. Removing the finish and gluing the bridge to the soundboard will lower the bridge. This is not necessarily a bad thing as you can shim under the saddle to make up for it and will give you room to grow.
The easiest thing to do would be to pull the bridge away from the top, squirt some medium CA into the opening, then 'click' the bridge down into place, squeezing out the excess glue and at the same time, pushing the top wood split back into place. Clamp and let it dry for 24 hours. Then, use thin CA to wick into the various finish cracks/soundboard split to fill them and let that dry for 24 hours.
Since there's probably still some wood fibers attached to the underside of the finish, this should give the CA some 'tooth' to grab onto, and hold the finish to the soundboard that it pulled away from.
Like Titebond, CA dries by evaporation. This evaporation also happens when the glue soaks into the wood and the solvents can evaporate through the surrounding wood. You can speed up the process by spraying on some CA accelerator, but it can cause the glue to 'boil', which weakens the joint.
Edited by DanSavage 2014-06-30 11:40 AM
|
|
| |
|
Joined:
October 2005
Posts: 4044
Location: Utah | I am surprised the top was finished before the bridge was glued on.
Something not mentioned yet is the addition of bridge bolts. You could drill 2 holes and bolt the bridge back down. Countersink the bolt heads enough so that you can put mother of pearl dots on top to hide them.
Bolts would reduce the concern of an adhesive failure in the future. You'd have to glue small reinforcement plates under the saddle but I don't think those would dampen the sound appreciably. |
|
| |
|
Joined:
October 2012
Posts: 1034
Location: Yokohama, Japan | Thanks again for the valuable insight FlySig and DanSavage. I always just assumed "all" Ovation soundboards were finished before the bridge was glued on, but is that not the case? From a 'manufacturing process' stand point, that seems to be the most efficient way to go and my other O's seem to be assembled that way too. Oh yeah, and DanSavage's superb "1619-4 Rebuild" looks like the finish is going on the soundboard before the bridge is glued on as well?
So, I think I'll re-strategize and take DanSavages advice, use medium CA and just glue the bridge back into place without removing it completely and use thin CA around the bridge area to fill in the finish cracks. Fortunately, the little "chip in the spruce top" was actually just finish that chipped away, and the wood itself is not damaged so I can fill that area in with CA as well. I also noticed that I can put my hand in the bowl from the sound hole and push up just a bit from on the underside of the long soundboard crack and it opens up just enough to apply thin CA there as well. I like the idea of bridge bolts too. My 1861 uses bridge bolts too. I'm assuming I should drill after the bridge is glued back into place, right? And take precaution to make sure the spruce doesn't splinter when I drill through the bridge and the soundboard. That sounds tricky since the bridge rosewood is much harder than spruce! DanSavage, are you planning on bolting the bridge for your "1619-4 Rebuild"?
By the way, can you estimate how much glue to apply for a job like this? The temptation is to just apply profuse amounts so that the adhesive just flows into all cracks and gaps, but when it comes to adhesives 'abundance' doesn't always correlate to 'adhesion' does it? And once I glue the bridge back into place, how much time will I have to clamp down the bridge with the "C clamps"? I've heard so often that CA is the same as "super glue" and there always is a time factor when working with consumer types of "super glue". If I have a limited amount of time, I'm going to have to practice putting the C-clamps in place before I do the actual work on this "O". I definitely don't want to end up putting this beauty in the trash! |
|
| |
|
Joined:
October 2005
Posts: 4044
Location: Utah | There are different versions of CYA glues. I think the ones you find in the grocery store are weakened and they cure slowly. This is to prevent people gluing their hands to their faces! In the hardware or hobby stores you may find a more instant version or one which is not weakened. CYA is not something I know a lot about wrt gluing woods.
Glue typically is described with 2 properties. One is ADhesion, the other is COhesion. Adhesion is how well it grips other materials. Cohesion is how strongly it holds onto itself. Some glues will have more cohesion than adhesion, which means the glue will fail at the surface of the material it binds to. If adhesion is stronger than cohesion it will fail in the glue itself. My experience with glues back in my previous career (failure analysis of electronic assemblies) we almost always found failed joints involved either a contaminated surface which killed adhesion, or a failure in the glue itself (a cohesion failure). The moral of the story is have clean surfaces and use as little glue as is necessary.
I've not bolted down a bridge before but the one source I found online says to fit the bolts first and then take them out. Then apply glue and put the bridge down, install the bolts and tighten them down to help clamp the bridge. Then apply an external clamp to the bridge. This presumes the glue is not instantly setting. To drill the holes in the top of the guitar I would clamp a backer piece of wood so when the drill bit exits the other side of the top it is held firmly and wont split. |
|
| |
|
Joined:
June 2012
Posts: 2317
Location: Pueblo West, CO | FlySig - 2014-06-30 1:00 PM
I am surprised the top was finished before the bridge was glued on.
Something not mentioned yet is the addition of bridge bolts. You could drill 2 holes and bolt the bridge back down. Countersink the bolt heads enough so that you can put mother of pearl dots on top to hide them.
Bolts would reduce the concern of an adhesive failure in the future. You'd have to glue small reinforcement plates under the saddle but I don't think those would dampen the sound appreciably.
A thread on the General forum talks about a 12-string that had its bridge pull up. (See: 12-String Dead; Stores with Inventory??)
If I were to hazard a guess, I'd say that someone in the Ovation organization got the big idea that they could save time (read: money) by completely finishing the tops, then just gluing the bridge to the outside. Not having to sand around a bridge, or over the masked area would save time and effort, but the end result is an inferior glue joint because you end up relying on the adhesion of the finish to support the tension of the strings.
The problem is that the high-volume production environment doesn't really lend itself well to slow-drying anything, be it glue, finish, etc. The more quickly a glue/finish, etc. dries, the less it will soak into the wood. I've already seen this with the epoxy used to glue the top on my 1619. It was a fast-drying variety which only grips onto the surface layer of the wood.
I believe this is why Ovation turned to using bridge bolts. They started getting a lot of warranty work for bridges that popped off, taking the finish with it and determined the most cost-effective solution was to go with the belt and suspenders solution.
In Arumako's case, I agree that bridge bolts would be a good idea, no matter what glue is used.
Edited by DanSavage 2014-07-01 10:19 AM
|
|
| |
|
Joined:
June 2012
Posts: 2317
Location: Pueblo West, CO | arumako - 2014-06-30 2:22 PM
Thanks again for the valuable insight FlySig and DanSavage. I always just assumed "all" Ovation soundboards were finished before the bridge was glued on, but is that not the case? From a 'manufacturing process' stand point, that seems to be the most efficient way to go and my other O's seem to be assembled that way too. Oh yeah, and DanSavage's superb "1619-4 Rebuild" looks like the finish is going on the soundboard before the bridge is glued on as well?
So, I think I'll re-strategize and take DanSavages advice, use medium CA and just glue the bridge back into place without removing it completely and use thin CA around the bridge area to fill in the finish cracks. Fortunately, the little "chip in the spruce top" was actually just finish that chipped away, and the wood itself is not damaged so I can fill that area in with CA as well. I also noticed that I can put my hand in the bowl from the sound hole and push up just a bit from on the underside of the long soundboard crack and it opens up just enough to apply thin CA there as well. I like the idea of bridge bolts too. My 1861 uses bridge bolts too. I'm assuming I should drill after the bridge is glued back into place, right? And take precaution to make sure the spruce doesn't splinter when I drill through the bridge and the soundboard. That sounds tricky since the bridge rosewood is much harder than spruce! DanSavage, are you planning on bolting the bridge for your "1619-4 Rebuild"?
By the way, can you estimate how much glue to apply for a job like this? The temptation is to just apply profuse amounts so that the adhesive just flows into all cracks and gaps, but when it comes to adhesives 'abundance' doesn't always correlate to 'adhesion' does it? And once I glue the bridge back into place, how much time will I have to clamp down the bridge with the "C clamps"? I've heard so often that CA is the same as "super glue" and there always is a time factor when working with consumer types of "super glue". If I have a limited amount of time, I'm going to have to practice putting the C-clamps in place before I do the actual work on this "O". I definitely don't want to end up putting this beauty in the trash!
The older Os, such as my 1619 had the bridges glued to bare wood. As I noted above, the problem with gluing the bridge to the top of the finish is two-fold. First, you're relying on the adhesion of the finish to the wood and in a high-volume production environment, the finish is of the quick-drying variety, which means the grip of the finish to the wood is tenuous, at best.
Secondly, you're relying on the glue to hold the bridge to the top of the finish. There are two ways glues bond: mechanical and chemical. With a mechanical bond, the glue gets trapped in the microscopic holes, divots, cracks and crevices of the two parts. With slow-drying epoxy, the glue soaks into the wood, which deepens its grip on the parts being bonded. In a chemical bond, the glue becomes one with the two parts.
All glues except hide glue use a mechanical bond, which is why you need to sand. i.e.: roughen up the surface of what's being bonded in order to give the glue some 'tooth.' The sole exception is when you add one layer of epoxy/polyester resin over another that's still in the green stage, which is to say, not fully cured, such as when seaming up a fiberglass piece in a two-part mold.
While I am finishing the top of my 1619 before gluing the bridge on, I masked the area where the bridge will be glued so that once the finishing process is complete, I'll peel off the masking tape to expose the bare wood underneath. The bridge on the original soundboard was done this way. Another method of doing this is to finish the top, then mark the bridge location and carefully scrape the finish away to get back to the bare wood layer. That seemed like a lot more work to me, and it would not guarantee that the exposed wood would make a good bond between the top and the bridge.
Yep. I would drill the holes for the bridge bolts after the bridge is glued back into the place and the split is repaired. If possible, you want to back up the inside of the spruce with a piece of hardwood. You'd clamp the wood to the inside, then drill through the bridge and top so you don't splinter the wood on the inside. You'll probably need a couple of bridge clamps to be able to reach that deep through the sound hole. If you have a woodworking supply nearby, go in and take a look around for C-clamps that will reach through the sound hole to the back of the bridge.
To answer your question, I'm not planning to bolt the bridge on my 1619. IMO, the bolts are a belt and suspenders solution to the problem created by gluing the bridge to the outside of the finish. As long as the bridge has a good bare wood glue joint, bolting is unnecessary.
While grocery store CA is the same basic formulation as hobby-grade CA, I would not trust it for gluing the bridge. If possible, find a hobby store that sells model airplane supplies and buy CA there. You buy different glues of different viscosity. I would also recommend buying some wood pieces to experiment on so you can get some experience with what to expect.
Generally speaking, you only want as much glue as is needed to bond the pieces. The less glue used, the better. Yes, you'll also want to do as many dry runs as possible so you can get an idea of what actions you'll need to take to get the clamps into place before the glue starts to set. |
|
| |
|
Joined:
March 2005
Posts: 12755
Location: Boise, Idaho | Dan has far more expertise than I do, but I have one caution about the bridge bolts. I have owned a few older Ovations with the hard, thick poly finish that they used to use, with finish cracks extending out from the bridge. Each crack seemed to start at the bridge bolt. I am sure the cracks weren't there for a while after they left the factory, so they started from stress on the finish in the area of the bridge bolt. None of the bridges ever pulled up, so I can only assume they started at the bridge bolt and didn't just start at the edge of the bridge. |
|
| |
|
Joined:
June 2012
Posts: 2317
Location: Pueblo West, CO | FlySig - 2014-06-30 3:59 PM
There are different versions of CYA glues. I think the ones you find in the grocery store are weakened and they cure slowly. This is to prevent people gluing their hands to their faces! In the hardware or hobby stores you may find a more instant version or one which is not weakened. CYA is not something I know a lot about wrt gluing woods.
...The moral of the story is have clean surfaces and use as little glue as is necessary.
I've not bolted down a bridge before but the one source I found online says to fit the bolts first and then take them out. Then apply glue and put the bridge down, install the bolts and tighten them down to help clamp the bridge. Then apply an external clamp to the bridge. This presumes the glue is not instantly setting. To drill the holes in the top of the guitar I would clamp a backer piece of wood so when the drill bit exits the other side of the top it is held firmly and wont split.
You are correct in that there are differing grades of CA. For this repair, I would not use the Super Glue, but would use a model-airplane grade found in hobby stores.
Of all the glues I've used, CA is the closest to hide glue. Both are very hard when dry, form airtight joints and will not creep when subjected to higher temperatures, which is good for luthery. Hide glue joints can be separated and reactivated, which makes it slightly better for woodworking. CA can be separated with acetone, but it takes a while to dissolve the glue, which is not necessarily good for the finish.
One of the real benefits of CA is their ability to wick into cracks without drying. This is a good thing because it can grab at exactly the wrong time and the only way to separate the two pieces is to break the wood. Typically, when building model airplanes, I would put the piece into place, then run a bead of glue along the edge of the joint allowing the glue to wick. Then, hit it with a couple of spritzes of kicker (accelerator) to force the glue to set in a few seconds.
I agree that clamping the bridge, then drilling holes for the bolts before gluing is a good idea. I hadn't thought about using the bolts as additional clamping devices, but as long as you get the bolts tightened before the glue starts to set, this would work well. As I note above, with CA, it's tendency to grab at inopportune times is one of its most frustrating properties. Bolting the bridge as part of the assembly process would probably work better with slow-drying epoxy.
If I were doing this repair with CA, I would probably drill and install the bolts after the glue has dried just to prevent any misalignment problems. |
|
| |
|
Joined:
April 2010
Posts: 823
Location: sitting at my computer | DanSavage - One of the real benefits of CA is their ability to wick into cracks without drying. This is a good thing because it can grab at exactly the wrong time and the only way to separate the two pieces is to break the wood. well, thought I was following along …'til reading (or misreading) that. ?? I would've figured it'd be a bad thing to "grab at exactly the wrong time."  |
|
| |
|
Joined:
June 2012
Posts: 2317
Location: Pueblo West, CO | SOBeach - 2014-07-01 1:16 PM well, thought I was following along …'til reading (or misreading) that. ?? I would've figured it'd be a bad thing to "grab at exactly the wrong time." I can see your confusion. LOL! It's good that CA is able to easily wick into already assembled glue joints because if you try to apply the glue, then assemble the pieces, it will grab, usually at the wrong time and this is a very bad thing because the only way to separate the two pieces is to break the wood. 
Edited by DanSavage 2014-07-01 4:54 PM
|
|
| |
|
Joined:
June 2012
Posts: 2317
Location: Pueblo West, CO | Mark in Boise - 2014-07-01 9:38 AM
Dan has far more expertise than I do, but I have one caution about the bridge bolts. I have owned a few older Ovations with the hard, thick poly finish that they used to use, with finish cracks extending out from the bridge. Each crack seemed to start at the bridge bolt. I am sure the cracks weren't there for a while after they left the factory, so they started from stress on the finish in the area of the bridge bolt. None of the bridges ever pulled up, so I can only assume they started at the bridge bolt and didn't just start at the edge of the bridge.
Someone, somewhere along the way probably thought that the bridge bolts were too loose, even when tight and that anything worth doing is worth overdoing.
As I was taught, the mark of an inexperienced mechanic is overtightened nuts and bolts.
Another thing I don't like is that Ovation machined out a 1/64" or so recess about 1/4" inside the periphery of the undersides of the bridges. First, this means that more glue is needed to fill the gap. More glue is less good. Less glue is more good. Second, if the recess doesn't get completely filled, it will allow the wood to flex.
Even my CL bridge has had this done to it. I can see no good reason this was done and I'll probably be sanding the underside of the bridge so it is flat with no recess so the glue is able to grab completely.
Edited by DanSavage 2014-07-01 5:09 PM
|
|
| |
|
Joined:
October 2005
Posts: 4044
Location: Utah | Perhaps Beal has an explanation for the recess. |
|
| |
|
Joined:
October 2012
Posts: 1034
Location: Yokohama, Japan | Thanks again for all of the fabulous input. There's a hobby store not too far from where I live. I think I'll go and look for some of that model airplane CA glue that DanSavage was talking about. Some medium viscosity CA glue for the bridge and thin viscosity CA for the cracks. I'll get some C-clamps and a bridge caul, do plenty of trial runs and practice using the CA on some wood blanks. It sounds like if I do this right the CA glue should be plenty to hold the bridge in place, but I think I'll bolt the bridge into place as a secondary measure. So I'll drill the bolt holes after the bridge has been glued into place. Both my 1861 and CC54i have bolted bridges; so I think I have some good examples for positioning the bolts properly. I won't be able to get started for a while, but I can't wait to give it a try! If I get through this without destroying this 1117-4, I just might get the courage to give another project "O" a shot! Wish me luck! |
|
| |
|
Joined:
June 2012
Posts: 2317
Location: Pueblo West, CO | Luck! :D |
|
| |
|
Joined:
April 2010
Posts: 823
Location: sitting at my computer | DanSavage - I can see your confusion. LOL! yeah, I'm a member of the 'easily confused club'. d'oh!  It's good that CA is able to easily wick into already assembled glue joints because if you try to apply the glue, then assemble the pieces, it will grab, usually at the wrong time and this is a very bad thing because the only way to separate the two pieces is to break the wood. Gotcha! thanks Dan
Haven't ever tried that technique before, assemble pieces dry then apply adhesive around the edges, will have to check it out. I'd be concerned tho the wicking action might not travel far enough inward away from the edges to insure full coverage to the whole break. ?? No doubt each situation is different: the size and severity of the break, the wood grain (or other material surface texture), and the viscosity of the adhesive. Another neat trick to experiment with!  |
|
| |
|
Joined:
April 2010
Posts: 823
Location: sitting at my computer | arumako - Wish me luck! Good luck! Take pics and keep us posted. |
|
| |
Need advice on a 1117-4 Project
