Very productive day today! After letting the steam-bent lower longeron bake in the sun for a day, I took off the clamps with good results. Here's the longeron in the jig.
For those of you curious, here's the amount of spring back after the clamps were released.
Now, the next step : There is an 11 inch splice that joins the front and back ash pieces to form the nearly 24 ft upper longeron. Thanks to Andrew King and Paul Dougherty, their advice made the process very easy. Here is how it is done.
First, the ash is rough cut on the table saw. I left about a 1/4 in. buffer between the blade and the cut line.
This jig was used to cut Paul Dougherty's Curtiss Jenny longerons and he graciously let me use it. Basically, it consists of two sides of plywood dadoed to make an angled floor to match the splice. This way, all eight eventual cuts would be identical. A router is used for the cutting as seen below.
Here's a finished cut. Very nice and precise. I practiced on a piece of scrap ash prior to cutting the actual longeron. I learned that the less wood the router has to cut, the easier the job. Also, I figured out the starting and stopping points and marked them on the jig.
Here's a finished cut.
Just for fun, I mated the finished longeron with the test piece (darker wood on left side). As you can see, it's a great fit!
Not only is there a splice, but the front longeron tapers from 1 1/2in. to 1 1/4 in. I used the table saw to rough cut again.
And sanded to the line with an oscillating spindle sander. This tool is a life saver!
After hand sanding, both upper longerons are now finished. More tomorrow.