Spar setting Jig

 

This is a so-so picture of a the jig that I used for the main spar. Click on this picture for a clearer and larger view of the setup.

It is basically an "I" beam with flat pieces of steel welded to hold the curve of the spar while it's being built. There are 4 pieces of 1/4 inch steel wielded onto the I-Beam and it is ratcheted into place with two straps. I used the square to measure the correct distance of bend. Also note that measurements must be taken at equal distances from the centerline to ensure symmetry throughout the spar.  The beam can be found at most metal scrap yards for very little money and when done with it can be returned or used for another assembly. Try to spend the extra time to locate the straightest piece possible , any bow in the I-beam needs to be taken into account no matter how slight.

 Unfortunately it has already served it's purpose and has been dismantled so I can't get dimensions for you. But if you reference the plans you should have no problem figuring out where to place the wielded spacers.

As a side note. IF you look at the picture closely you may wish to make sure that your supports are of sturdy construction, ( my sawhorses actually got bent in a Honey-dew project !) . But you wouldn't want your significant other waking you in the middle of the night saying that they heard something go boom in the workshop!!!