(I was going to mark this thread "OT" but then realized that it is T-related.)
A friend of mine from my Air Force days some 50 years ago (good grief!) probably has forgotten more about woodworking than I could ever hope to know, and posted this link on Facebook. I am assuming it could be used in forming wood for a T as well as for a boat.
That is cool err I mean HOT! be an easy way to steam a tack strip.
Excellent technique. Why didn't we think of that?
Thanks for the link
What a great idea! I guess I've always done it the hard way.
The doubt in my mind here is not in the technique of using a bag to hold steam but that the board will be free of any and all "spring back" when released. The mold the man made seemed to be of the final shape desired and in general I found that if you want a board to bend to a final radius of 2 feet then you need to put it on a form that is a much tighter radius than 2 feet to allow for the spring back.
I think the man said that the steaming process continued on for a while even after the piece was in place. I guess this allowed the wood to soften even more and relax, reducing spring back.
John -- You're right about the spring-back. Back when I was making parts for Windsor chairs, it took a few tries to get the form the correct size so that the bent piece would end up the desired shape.
But as Herb said, letting the piece "soak" the additional time in the steam might reduce the spring-back. One of these days, when I get a round tuit, I'll try that method on a tack strip.
But with the steam bag approach you still have the issue that once its on the form it is only being steamed on 3 sides. Contrary to popular myth the wetness has nothing to do with the steam bending process other than supplying the heat and the wetness is in fact undesirable. It causes the wood to dry out. The main thing that does the job is the heat but it must be constant and everywhere the same temperature which is why steam in a box or bag works so well. There is a ton of info in the various patents on steam bending equipment and what is funny is that the later machines (and I mean over 100 years later) have it basically wrong. They simply say that a lot of broken pieces is common and that the machine mainly needs to deal with that while the early machines didn't split or break the wood and for good reason if you delve deeply into the design of the machines and the makeup of wood and how its fibers are affected by heat in the steam bending process. I think that the original steam bending art is somewhat lost and replaced by a lot of misinformation. If you get zero spring back then you have steamed the wood too long and it is already turning to pulp. You only get one shot at steam bending a piece of wood and you cannot re-steam a piece of wood and re-bend it. I have seen numerous articles showing people loading up an oven or boiler and then cooking a lot of pieces together. Then they take them out one at a time and put them on a form while the others stay cooking. That violates just about every rule and I personally can attest to that. Take a good look at a steam bent back chair and notice that the wood is nicely bent but also not warped, rough or dried out. It has been properly steam bent.