Back To Drilling The Last 2 Wing Rear Spars

 Ok I've only drilled 2 holes, but I'm back working on the spars. The holes are the 5/16" holes which go vertically through the spars for attaching the wings.  Here are the links to go back and look at the details of how I did this for the first spars.

Aligning the ShopSmith to get accurate holes.

Positioning the drill.

Drilling the holes

After rechecking the alignment of the drill to the table and the fence we're ready to drill.  The spar is supported on 2 roller stands.  I moved the spar so the first 2 feet could be used to align it parallel to the fence.  The actual hole is 1-1/4" from the end of spar, therefore I wanted a longer edge to get it parallel.

The first pass is with a 1/4" drill.  The rear spars are 1-1/14" thick so I used a 1/2" gauge block between the drill and the table so the hole is centered on the spar width.  I center punched the holes with the optical centerpunch.

I clamped the spar to hold it flat and drilled just over 1/2 way through the spar.  Then the spar was flipped over and drilled from the other face of the spar.

The 2 halves of the hole aligned so well that a 1/4" bolt went easily through the hole.

I sort of repeated this process to drill out the hole to 5/16".  I used the 1/4" drill bit to align with the drill centerline, clamped the spar to the table, then switched the bit to a 5/16" bit and again drilled over 1/2 way through the spar, flipped the spar over and repeated.  After drilling the second side I used a letter P drill to open the hole slightly and in this case drilled all the way through, into my backing board.

Again a 5/16" bolt goes easily through the hole.

Now I need to drill all the holes for the fittings, etc.