This morning, I slept in disgustingly late.  I got up around 11:30 am.  Sometimes, you just need to get caught up on your sleep.  I started around lunch time by reviewing what my plan of attack would be for riveting the ribs to the main and rear spars.

One common theme that rang through when I reviewed other builders web sites was to securely mount and clamp the main spar to a solid surface.  I used some quick clamps to clamp the main spar to my work table.  My work table is heavy and solid.  This made a really good surface to clamp to.  In order to prevent marring of the main wing spar, I put some tool box anti-skid/liner between the spar and the tabletop.

This was our first time riveting AN470 rivets with the rivet hammer and bucking bar.  We made it through all the rivets without a single smiley.  WooHOO!!!

A couple of things to do when riveting the ribs to the main spar:

• I dialed up the air pressure going to the rivet hammer.  Remember, you are supposed to set a rivet with as few hammer strikes as necessary to set the rivet.  The rivets you are setting on the front spars are AN470AD4-5 and AN470AD4-7's.  They take alot more force to set than 3-'s.  I found that 70-75 psi worked well for my Sioux 2x hammer.
• Tami and I had to put noticeably more force/counterforce when bucking the 4- rivets.
• Only cleco the rib you are about to rivet to the main spar.  When riveting, the ribs need to be slightly moved out of the way in order to get the rivet hammer in proper position.  Only clecoing one rib at a time, you are not fumbling over the other ribs.
• On the upper and lower most rivets, hold the rib flange against the main spar.  When you rivet those rivets, the riveting process will tend to push the flange away from the spar.  It is not a problem with the inner rivets as the flange is held in position by adjacent cleco clamps.
• On the side being bucked (forward side of spar), put masking or duct tape on both sides of the row of rivets in case your bucking partner slips off the rivet.

After we got done riveting the ribs to the front spar, the following had to be completed:

• Since you cannot rivet the W-712-R Outboard Rib to the main spar yet, I cleco'd it to the main spar so that I could mount the wing in the stand.
• Riveted the W-712-R outboard rib to the rear spar with AN426D4-5 rivets.  These rivets will sit underneath the aileron hinge bracket assembly so they must be flush rivets.
• Drilled the outboard rib with two holes (near the rib flange) in order to attach a temporary aluminum angle so that you can hang the wing on the stand.
• Tami and I placed the wing on the stand so that sag and twist could be taken out of the wing skeleton.

I bolted the aluminum angle bracket to the wing rib such that it was at the same height as the wing spar reinforcements on the inboard side of the wing.  This way I knew the wing would sit level since I went to some effort to ensure that the wing stand aluminum angle was level from one post to the other.  That effort paid off, see picture of smart tool further down in this log entry.

I got some of Tami's sewing thread and strung it from the inboard and outboard line of rivet holes.  When the wing is properly setting in the stand, the thread should intersect through the center of each of the rivet holes (bottom holes).  I was amazed at how much sag there was in the spar just setting in the stand.

After clamping the wing to the stand, I measured the twist in the wing.  To measure the twist, hang plumb bobs over the main spar at each end of the wing.  Measure the distance between the rear spar flange and the plumb bob string.  Initially, the wing only had 1/16" of twist.  1/2 turn of the turnbuckle support(s), and the wing had no measurable twist.  Woo-HOO!!!

Once I got the twist taken out of the wing, I secured the rear spar to the wing stand with some scrap 2" x 4" lumber and a quick clamp.

I took the cheapo tire jack out of Tami's car and propped it up on some scrap wood.  Taking the sag out of the wing was pretty easy with the jack.  I may come up with a better jack arrangement, but this will do for now.

A couple of turns of the jack handle, and the thread centered right up on the aft line of rivet holes.  The main spar was true all the way across when jacked from the center.

After I took the twist and sag out of the wing, I put the smart tool on it to see how well it sat in the stand.  I would say this is pretty level.  All of the effort to ensure the stand aluminum angles were level between posts paid off.  I did not have to do any shimming to get this reading on the smart tool.

The right wing is in the stand and is as close to perfectly true as I can make it.  I went back and double checked all measurements when I thought I was done to ensure that changing twist did not change sag and vice-versa.

Tomorrow, I plan on drilling the wing walk doublers and the right wing top skins.  Today felt really good in that it was the first day in a long while that I felt like I accomplished some real building.