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Steam bending inwales/outwales

Posted: Mon Nov 04, 2013 4:42 pm
by Wendell
Hello guys!

Tried steam bending my scuppperd cypress inwales yesterday. My canoe design has very recurved stems and a pretty severe up swing at the bow and stern so I wanted to steam bend my inwales before I tried glueing them in. The inwales are 3/4 X 3/4" and are tapered to 1/4" starting about 3' from each end. I steamed them for about 20-30 minutes and when I clamped and bent them, they cracked!! Did I steam them long enough, or does cypress just not bend?? I steamed my ash stems with NO problem.

Re: Steam bending inwales/outwales

Posted: Mon Nov 04, 2013 5:08 pm
by Bill Edmundson
You can't steam too long. I've never used cypress so I don't know about it.


Re: Steam bending inwales/outwales

Posted: Mon Nov 04, 2013 8:09 pm
by Ibrew2be
Wendell, at the Great Lakes Boat Building School, the rule of thumb taught for steaming wood for steam bending is to steam for 1 hour for every inch of thickness of the stock. So in your case, that would suggest steaming on the order of 45 minutes.

Another thing to note about the wood used in steam bending is that the greener the wood is, the better. The best scenario is when the steam applied is heating moisture which is still within the wood structure.

A final thought. Not sure what you're using to do the steaming, but it's best if the steam can contact all surfaces of the wood. So for example, if you were steaming two pieces of stock side by side in a steam box, you don't want them touching. Similarly, you'd want the stock supported during so that you minimize contact with the "floor" of your steam box.