Tiedowns, interrupted

Well, I tried to get some good work done on the tiedowns today, but it didn’t really work out.  First, I had to fabricate four spacers; the tiedown hardpoints themselves sit against the spar reinforcement bars and attach there with bolts.  However, the aileron bellcranks mount at the same location on the other side of the spar, and bolt into nutplates that will be riveted onto the hardpoints.  Since these mount points are inside the spar bars, the spacers go in there.  They’re pretty simple, just 2″ lengths cut from bar stock, with a 1″ lightening hole cut in the center.  They get drilled in assembly with the spar and hardpoint.

I made the first cut using the bandsaw…but apparently I need to replace the blade on that, because it really doesn’t want to cut straight, and wanders pretty badly.  I tried playing with the blade tension to no avail.  As such, my first cut produced a piece that was worthless.  So I made the rest of the cuts using the good old hacksaw, and then cleaned the cut edges up on the grinder.

At this point I had an odd sort of internal debate; the plans call for 3/16″ holes for the AN3 bolts, so I grabbed a 3/16″ bit from the drawer.  I went to check it against the predrilled holes in the spar and was kind of surprised when it didn’t fit.  Hmm, are the holes drilled undersize?  I wanted to be sure, so I got an AN3 bolt…huh, it drops right into the hole.  Even more odd.  Then I got the 3/16″ bit from my El Cheapo bit set…it drops into the spar holes OK.

I decided to drill a hole in my scrap piece using the apparently slightly oversize bit to see how the bolt fit in the hole.  The results sent me in a very different direction; while the bolt fit OK without a ton of apparent slop, the hole I drilled was kind of ugly.  Seems like it’s tough to keep the drill straight while going through thick pieces like this.  So I decided it was time for a drill press before I went to drilling these pieces.  After a little research, I settled on a model sold at Lowes.  

When I got there, though, the parking lot was oddly empty, despite it being about 6:30 and the door stating that they were open until 8 on Sunday.  An employee in the parking lot explained it to me…they closed at 6 due to it being Easter.  Ohhhh…well, so much for getting my drill press today.  Guess I’ll stop by again after work tomorrow.

So I just went ahead and knocked off for the day.  More to come tomorrow…

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