Here's what's left of the A braces from my 1619.

The 1st gen bowls were vacuum bagged. While this produces very high quality parts, it's pretty labor intensive.

Here's a schematic drawing showing the laters used when vacuum bag molding.

And, here's a part being molded. Even though this is a slightly concave part, the process is the same for a male part like the 1st gen bowls. Notice the folds in the plastic vacuum bag. These can also be seen in the pics of the 1st gen bowl I posted and this is how they get there.

The later hand-laid bowls, like the one seen in my 1619-4 thread, are made in female molds.

But, instead of squeegeeing the excess resin by hand, and then letting them cure naturally, they put them into an autoclave which applies vacuum, pressure and heat. Here's a schematic drawing of how the bowls laid up. This drawing shows prepreg, but the bowl I've got was done with plain old resin and 2x2 twill cloth. Generally speaking, prepreg uses fiberglass roving, not woven cloth.

And, here's a carbon fiber bowl being molded in a female mold. This part is placed into the autoclave. The pressure squeezes out the excess resin and the heat makes the part cure faster. Making parts using this method is less labor intensive and the finished parts can be produced more quickly. Not as quick as SMC prepreg, but a lot quicker than letting the resin cure naturally. So, you get high quality parts more quickly.

Any discussion about vacuum molding composites wouldn't be complete without also mentioning resin infusion. Instead of laying up cloth and wetting it out with resin, then vacuum bagging it, dry cloth is laid up, vacuum is applied and the resin is sucked through the cloth. Resin infusion is slightly more wasteful of resin, but produces the highest quality part with the highest cloth to resin ratio.

To my knowledge, resin infusion is not used with autoclave molding, nor did Ovation use it in their molding process.

Dan...this is almost as good as 24.

Ok...but back to scholar's question (i think)...Do you think that they made the 40th RI shinys the old fashion way? 

Dan...I just enjoy the dialog, regardless of the level of commitment.

Maybe someone here can pop a few pictures of their 40th bowl, inside and out for your consideration.

I bought one with quite a bit of damage to the bowl...Scratches from a belt and what looked like to be a chemical melt from epoxy or something. I sent it to the MS and bowl came back looking brand new. As badly melted as it was, I thought it would have to be replaced. Nope and for some ridiciously small fee. There is no doubt in my mind, we are going to miss those guys tremendously. 

Oh boy now this goes into the territory like at AGF where they like to discuss the effects of various body woods on tone ... 

So I am curious, as the late 70s seemed to have been a transitional time from handlaid to composite, what kind of bowls were used on the production Adamas 1687s of that time? And was that reproduced for the 30th Anniversary RIs?

Generally speaking I would expect stiffer epoxy to make better musical instruments because it would transmit vibration better than softer epoxies which would tend to absorb (read: dampen) the vibrations. As I mentioned earlier, excess resin only adds weight, not strength. Excess epoxy would also dampen vibrations. Vacuum-bagged parts are superior because it squeezes out the excess resin. 'The Book' states, the 1st gen bowls were considered to be better than the 2nd gen bowls. This can be directly attributed to the the difference in how the two generation of bowls were manufactured.

Similarly, the finish, any finish, applied, dampens vibrations. The best is no finish. Next, is french polish, followed by varnish, then nitro, polyurethane, and lastly polyester.

WRT the contour bowls, my brother stayed with me last year and we had a chance to play together, he on my 2078TX-5 and me on my Book Elite. One thing that struck me while he was playing was how loud the 2078 was. I kept thinking to myself, 'Dang! Take it easy. You're drowning me out' It wasn't until later that I realized that it wasn't his playing, but the guitar itself that was loud.

This thread hasn't been active for a while, but I suspect it gets read quite a bit (and it's still very informative.)

What brought me back to it was;

I was doing a little work on my 1979 Pacemaker (1115) and remembered that, back when I first got it (maybe 8 years ago?) and peeked inside, I noticed some odd-looking tan cloth/material (or something) in the "tailstock" area. (It appears to be a cloth bowl, weave patterns are visible inside, and that would fit with Dan's timeline.) I never figured out what it was, and I love the guitar, so I basically forgot about it until I looked inside it today with a flashlight. Out of curiosity, I checked the OFC and reread this entire thread. Only when I looked at those photos Dan originally linked in his first post did I realize that the inside of my Pacemaker looked EXACTLY like what he'd seen in that old late-60's Balladeer bowl in his photos (here's a reduced copy of Dans photo.):

Apparently, that "rough" area wasn't necessarily unique to those very early bowls afterall.

I don't think it's an aftermarket repair, although it's possible that someone reached in from the soundhole to patch a hole or something. The outside of the bowl looks nearly perfect, except for one barely-detectable indentation in that general area which looks like it was hit from the outside by something. It could have been a factory repair, since they certainly would have been able to repaint the entire bowl to make it unnoticable from the outside, but has anyone ever heard of the factory patching bowls from the inside (with the top still attached) to repair them like that? (especially sometime after 1979?)

A simpler explanation might be that it was (sometimes?) deemed unnecessary to sand and paint that part of the inside of the bowl because (almost) no one would ever see it anyway once the top was attached? (Or, maybe, if a bowl didn't pass inspecton, it was patched like that and then put back into the production line?)

Interesting mystery (great guitar, regardless.)

Here's a bunch of pics of the inside of the various guitars I've worked on. If the inside of your bowl looks like these, then here's my explanation for the rough area.

It's simply a reinforcement for the strap mount. The fiberglass bowl is pretty thin -- two layers of cloth. This area of the bowl would distort with the weight of the player's arm pushing down on the lower bout while playing with a strap. To prevent the strap button (molly) from tearing out of the bowl, the MS added these extra layer(s) of cloth.

The rough surface texture is because they wet the area of the bowl where the cloth was going to go with epoxy, then laid on the cloth and wet it out. To get a smooth surface would have required a top coat of epoxy.

Since no one was going to be 'touching' this area, or even seeing it, there was no reason to 'waste' the extra epoxy.

The exception is the first bowl. This is Paul's 1117, which got a hand-laid bowl at its most recent factory visit. When the MS added the extra cloth, they top-coated it with epoxy.

If it's 'tan' that's just years and years of accumulated dust collecting in the nooks and crannies of the rough fiberglass cloth. If you were to take a stiff brush to this area, you could return it to its original color -- black. My 1111 looked the same way (see below) until I brushed out all the dirt.

Paul's 1117-4

1111-4

1113-4

1117-4

1617-4

1619-4