Sunday, June 27, 2010

Six little screws

I'm still buggered by those six little screws that have been taunting me since the last page of Section 21. It looked so easy! Just put six screws up through the belly skin and attach them in place with six little lock nuts - how hard could it be?

The first sign of difficulty came when I couldn't reach both the screw head and the nut on the other side of the skin at the same time. That's when I knew I was going to need help. That should have been easy too, but I soon learned that the help available to me within the family was not up to the task. The nuts are pretty tight on the screws and try as she might, young Co-pilot Egg simply couldn't hold the socket wrench tight enough. I enlisted outside help, but it was quickly determined that part of the problem was the insufficiency of my tools., The socket I had was too shallow to allow the inch long screw to be fully threaded onto the nut. The suggested alternative was to go to Harbor Freight on a procurement mission for nut drivers. No problem, that, since I also needed a tube cutter for the pending fuel line work.

Harbor Freight did have nut driver sets, but none of the sets contained the required size. The nuts in question are a relatively exotic 7/32" and the Harbor Freight nut drivers skipped from 3/16" (6/32" for those of you that need a translation) to 1/4" (8/32") with no intermediate stop at 7/32". While the sizing of all Harbor Freight tools is somewhat approximate, I didn't think I could count on a convenient 1/32" spread, so it was off to Sears, Home of Precisely Sized Yet Onerously Expensive Tools. It wasn't all that bad, as it turned out. $3.79 for a deep well 7/32" socket. I wouldn't want to buy a 64 piece set at those prices, but it was okay for a one-off.

With the nut now held firmly in place with the Craftsman Unaffordium socket wielded expertly by a manly helper, there was only one other possible point of failure: the screw head itself. Which is, naturally, where the next healthy application of FAIL came from. The fit of the screws through the nuts is so tight that the screwdriver finds it easier to just eat away at the screw head than to torque the screw into the nut. We managed to get two of the six installed, had to use the Dremel to cut two partially installed but completely ruined screws out of their holes, and ruined the remaining two screws in abortive attempts. I now have replacement screws and nuts on order from Van's, along with a preemptive order for more fuel line because I'm pretty certain how well that job is going to go too.

In the meantime, I placed a request for helpful hints on the Vans Air Force web forum. To date the best reply is "tap the nuts with an 8-32 tap first to loosen them up," followed closely by "use Loctite to keep them fixed in place if you do."

That sounds like a workable plan.


Torsten said...

I'm just at this step now, Dave. What did you end up doing? Did you follow the tap and Loctite approach for the last 4 screws?

DaveG said...

No. I ended up ordering replacements and the new ones went on easily. I think the first set must have been the wrong size or something.

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