I posted briefly about this guitar a few weeks ago when it arrived in my shop. I spent a week or two deciding on how to approach the repair and completed the job today. I hadn’t found much information about fixing these models of Ovation online so I thought I’d document my process in case it could help someone in the future.
This Adamas 1597 arrived in the shop with the top separated from the bowl, from one side of the next extension all the way around to the other. Prior to arrival in my shop it spent a year in the shop of another repair guy without much progress being made. Eventually the owner took it back and asked me if I’d like to take a shot.
The top on these models are a thin laminate of carbon fiber and veneer. The bowl is the usual Ovation fibreglass yacht hull. The top was loose but the binding remained glued to the bowl:
It looked to me like the neck and fingerboard extension were the only thing keeping the top in place. Gentle heat easily released the FB extension. Undoing the two neck bolts was all it took for separation to be total.
The underside of the FB extension (and the portion of the top it was glued to) were kinda funky, with a hunk of (presumably not factory) wooden shim and a thick buildup of epoxy on the top - a build up at least 1/16” higher than the top finish itself. The neck looks to have been on and off a few times.
The top seemed to have almost no residue of any adhesive on it - the sole exception was a few inches near the tail with some thick gobs of rubbery stuff that looked like it came from a prior repair. The rest of the top was as clean as a whistle. The fibreglass linings in the bowl sported a layer of what I presumed was epoxy - it clearly showed the indentation of the weave from the carbon fibre top:
I’m slicing away an extra fillet of epoxy here as part of the cleanup but the shot shows the “weave” pattern in the epoxy.
The epoxy itself was incredibly soft and rubbery. Clearly it had totally lost what grip it once had on the top, and even it’s bond to the linings was tenuous - it scraped off cleanly without much effort:
I really don’t know why such a total glue failure occurred - a factory error in epoxy mix ratio? Exposure to extreme environmental conditions? Surface contamination on the top?
Getting good adhesion was going to be key. I spent some more time re-scraping things to get the lining surface as clean as possible. I roughened it slightly with coarse sandpaper and washed both it and the underside of the soundboard down with a strong detergent to get rid of any residual amines or waxyness.
To glue up I chose a high strength boat-builder’s epoxy. My main concern was dealing with squeeze out and the difficulty of keeping the finished exterior surfaces clean of epoxy residue during the glue up. I didn’t want goobers of epoxy running everywhere inside the bowl either.
The top itself would not drop directly back into its original location on the bowl without some internal pressure to manipulate the rim outwards - but push it just right and top would pop back into place and be held there tightly, with the binding squeezing it from the outside. This greatly simplified matters.
I decided to thicken the epoxy and try to apply just the right amount so I could pop the top back into place and have it sitting down on a thick bed of the stuff. My aim was to get the top held tightly by the bowl itself, in firm contact with the epoxy layer, without the need for any additional clamping which could cause squeeze out. I went with a slow hardener to give 60 minutes of working time, mainly to give me plenty of time to clean up. I thickened the glue to about the viscosity of soft-serve ice cream with a high-strength filler designed for structural applications.
I masked off the sides and top, gloved up, spread the glue and changed gloves before handling the top. I popped the top in and peeled back the masking tape. There were a few tiny beads of squeeze out to deal with but in general things were neat. The next 20 minutes were spent wiping with soap and water and lots of clean rags as insurance against any tiny smears that might manifest themselves once things had cured. I set the guitar aside for 24 hours.
The next day I scraped the area of the top where the FB extension would lie clean of epoxy buildup, fashioned a wedge to go between FB and top for correct geometry, bolted the neck up and glued the FB extension down with a little fresh epoxy.
Some strings and a setup later and she’s back in action. Geometry is good and this thing can play cleanly with action at 3/64ths and 5/64ths
Fingers crossed the top stays on for good this time round!
