Greg Newell wrote: > Well, the ribs could be glued either one or a few at a time making the > process somewhat easier. I was thinking of attaching one end with a spring > clamp or even a screw that could later be removed and plugged to hold one > end. The other end would conform within the melamine pattern. Doesn't that pretty much shoot the ease and simplicity concept of vacuum bagging in the foot? > Assuming everything else works out happily, your clamping > pressure (unless you make a wide footprint caul for each rib) > is limited to some fraction of atmospheric pressure. It looks > like 12 PSI is about the best you'll do. Most everything but > epoxy ought to reasonably have at least three or four times > that. Some say a WHOLE LOT more than that. So what's the glue > used that waits that long for setup, and doesn't need over 12 > PSI clamp pressure? > > > This is not what I read about vacuum clamping. As I understood it the force > is quite high indeed. I suppose that it remains to be seen. Yea, I've seen the fantasy numbers too. They typically quote the total pressure on a big square inch area, which sounds really impressive. When you reduce these big acreage numbers to PSI, it comes to about 12. A vacuum clamping system isn't going to produce a higher PSI than the atmospheric pressure allows at the assembly altitude unless you have a clamping caul of a greater square inch area than the footprint of the glued surface. >One of the > benefits to this type of clamping is the claim that the glue permeates the > pores of the wood better and makes a more lasting joint than otherwise > attainable. Cute, I hadn't seen that one. There are lots of claims. Does this one mean anything real? What's the established life of a glue joint, for any given glue/wood/prep/clamp method/atmospheric pressure compared to any other? The folks making the claims don't seem to have any real information either. > I'm not sure if there will be a benefit or not. Time and trial will tell. I > am at least willing to give it a try and find out. I hope the education > isn't too costly. Thanks for your input. This is the realistic stuff. Pending actually trying it and generating real data, it's not all that clearly superior, or even adequate, a process. Ron N
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