FWW's article on Glue-Ups Fact or Fiction?
Did anyone else have fear struck in their heart by FWW's article on how to glue up a panel. I've obviously been doing it all wrong for 40 years. I expect the next time I look at a panel I've done I'll be watching it come apart as I watch. I'm not arguing with the author, but I'm sure I've been using a lot less clamps and a lot less pressure than he recommends. Yet I look at panels every day and can't think of one that has failed.
What do the rest of you think?
The author's credentials are impressive; so I feel uncomfortable in questioning his conclusions. But . . .
Fw`s Article On Glue-ups Or Friction
If they would put a little more Fine Wood Working in the magazines and a little less b.s. it would suit me fine. Next week they will have a clamp with a torque wrench on the end of it they are testing. Its more like a consumers report than a wood working magazine. Barry Bruner
I am of two minds on the topic
As an engineer I was interested in the article and actually disappointed that it was so brief. What I would have liked to have seen would have been a graph of resulting joint strength versus clamping pressure. I will bet the curve has 3 distinct regions (too little, approximately right and too much) I would guess there is an ascending ramp of strength versus pressure on the too little pressure region , then a flatish portion where the wood is breaking next to the glue (over a range of clamping pressure) and then finally a descending ramp when you get into the starved joint region from too much pressure.
My guess is that the reason so many people are shocked and express either concern about previous glued panels or feel like knocking the article is that all the gluing methods they have been using are working and they know it. I would not be surprised if there is a pretty broad pressure region where joints achieve at least 80% of maximum strength (from the author's quoted pressure values). Recall from FWW #192 that the loose bridle joints (no wood contact with a 1/64" gap) for PVA were at least 80% as strong as the tight fitting joints.
Everybody complains about FWW. There is always something I like in each issue and usually a lot I can do without, but of all the magazines I have ever read, they are the only ones I keep and reread. I myself most like the articles about furniture and about wood itself. Garrett Hack wrote an article recently about 5 underused North American woods, that was a really cool article.
How about Vacuum Bagging?
Haven't read the article, but hearsay from another source indicated a need for about 1200 PSI clamping pressure for flatsawn sugar maple. If that's correct, and is any indication of the general need, I guess you can forget about vacuum bagging veneer work since the most a vacuum bag can give you is only about 1/100 of what's needed.
Let's see now. At 1200 PSI, a 1 square foot veneered panel would require a 86.4 ton press.
Obviously something's not right with this picture.