Posted 2022-05-13 8:00 PM (#557332) Subject: Adamas top reglue
Joined: May 2022 Posts: 1
Howdy everyone - I'm JD, and I repair guitars for a living... I've worked on Ovations in the past but I have no experience working on the Adamas models with cf tops. And one just arrived in my shop. I'm hoping someone with experience could help me work out if I can offer the owner a quality repair. He's shown the guitar to a few local repair guys and been turned down them all. I'd like to help him if I can. The "mothership" is around 8000 miles away as the crow flies, so he isn't inclined to bear the shipping cost of returning it for them to repair.
This Adamas 1597 arrived in the shop with essentially total separation of top from bowl. The cf top itself is separated from the lining. When it arrived the top was loose from one side of the fb extension all the way around to the other side of the fb extension and it appeared the glued fb extension was the only thing keeping the top on at all. Undoing the neck bolts proved this to be the case, as neck and fb came away cleanly as one piece. I heated the fb extension and loosened it from the top without issue and set the neck aside.
There is no epoxy (I presume that's what they use at the factory?) at all adhering to the inside of the top - it all remains on the linings. And it is GUMMY. You can scrape it off easily with your fingernail. It clearly has no strength at all, nor a strong bond to either surface. I have no idea if this is a chemical failure of the adhesive itself due to a bad component or incorrect mix ratio, or whether the guitar was exposed to enough heat to cause the epoxy to turn to mush. At this point it doesn't matter.
Cleaning the gummy old epoxy from the linings gets me back to a very clean, smooth and shiny surface. This leads me to the first of my questions: Should I do something to roughen this surface before applying new epoxy? I feel like in its current smooth state a mechanical bond would be difficult.
Question two would be - is any special prep of the inside of the top required prior to gluing? There's texture there from the weave of the CF fibers ... I'm hesitant to sand or scrape this surface in fear of smoothing it out to the point that, again, it would impact a mechanical bond with the epoxy.
The top itself drops perfectly back onto the bowl, inside the binding, and almost 'clicks' into place the fit is so tight. I don't anticipate needing any clamping beyond perhaps a few wraps around the bowl with a rope or strap to make sure nothing moves during cure.
Question three is: my usual go-to for repair jobs that require epoxy, is a high-strength, slow cure boat-builders epoxy, plus structural filler additive to get the requisite viscosity for the job. Is this ok for these Adamas tops?
Like I said, this guy has been shopping his axe around to various repairers unable to find someone to take this on. It doesn't actually seem like a difficult job. But it's got me nervous ... do these guys know something that I don't?