Sunday, May 8, 2011

A new day

Having had a distinctly unproductive day on Saturday, I figured Sunday could only be better. To start the day off, I revisited the aborted attempt at tapping a couple of 10-24 holes in the pins that will hold the larger wing pins in place, who in turn will would the wings onto the airplane both in flight and on the ground. The first of those being pretty near and dear to my heart, as you can imagine.

I got to thinking that perhaps I was a tad over quick in blaming my woes on the well respected Harbor Freight Tool Emporium and maybe, just maybe, there was a little fault on my side of the equation. For you see, I had not verified that the starter holes in the pins were actually of the correct diameter for tapping to a 10-24 size. I pulled out my handy Aircraft Mechanics Handbook and took a look at the size required:

A-ha! A #26 bit! I have one of those, so I tried it out in the existing starter holes. It fit with room to spare. So there, Harbor Freight. Not. My. Fault. In fact, the Sears tap included a #25 bit, which is one size larger, and it fit easily into the holes too.

I clamped in the first pin, gave the tap a light coating of Boelube, and it screwed in as easily as a light bulb. Thank you, Sears.

These pins will have magnets inside of them that will work as a safety switch. If the pins are not installed, or not installed correctly, the magnets won't close the switches that allow the engine ignition to work. The first step was to find the magnets and switches in all of the bags of stuff. Luckily, it was a "find one and you've found them both" situation.

I was less lucky in finding the two screws that I needed. I read through the inventory sheets over and over to no avail. At one point I even sent a text message to Kyle, apprentice roadie and catering assistant for The Jackson Two, to ask if he remembered having had any trouble finding those little buggers. "Nope, they're in one of the 'Misc' bags."

 And so they were. There they are, plane (heh, 'plane' instead of 'plain') as day: 10-24 BAFFLE SCREW. Well, they sure had me baffled! [rim shot]

With the wonderful Sears tap, the screws rolled right in. The magnet went in easily too.

The magnets are held in with epoxy. One of the nice things about having scrap metal lying around is that there is no shortage of mixing surfaces and tools:

One of the not quite as nice things about having scrap metal lying around is that it sometimes has dangerous edges and points. I gave myself an impromptu TB test with this one:

I held the pins upright in the vise while the epoxy set.

Then I found an easier way:

Next I was supposed to cut 1/4" pieces of clear tube and push them down into 1/4" ID bushings. That sounded a lot like something that would be a pain to do, so I went a different route. First I tapped the full length of tube into the bushing.

The bushing was already 1/4", so the net result was the same.

All I had to do was cut off the excess tube.

The little pins inside the bigger pins are spring loaded. The springs slip right in.

The pins, however, did not. They were quite stiff and very reluctant to go into the bigger pins. I buffed the internal pins with a small piece of Scotchbrite pad, and smeared a little grease on them. After working them in and out of the tubes for awhile, everything got loosened up. The screws and bushings were put in to finish the assembly.

I couldn't think of a better place to store them than in the airplane, so in they went.

Having finished something successfully for the first time all weekend, I decided to push my luck and go on to the next part. These are the electrical transfer plates that will meet with the plates in the wing roots to carry power and ground out into the wing. They get trimmed and drilled to match a provided template.

Clecos and clamps are used to ensure that the plastic part doesn't move in relation to the template.

Then the terminals are separated from a strip. Eight are needed per side, ten are provided. The band saw made short work of the job.

The rivets sit way too close to each other for the rivet puller to get in there, but I was afraid to just pull one rivet first and hope that the terminals were still loose enough to turn for alignment. I ended up pushing the second rivet in from the back side and holding it in place while I pulled the front side rivet.

Taaa-daaaaa! Perfect, right? Really?? Look again. Still think it looks okay? Well then, ask yourself this: what am I going to use for a template on the other one of these if I leave it riveted to the first one?? Ah, there's the problem: it's not supposed to be riveted to the first one.

Drill out the rivet, swear profusely.

In the end, though, it turned out nicely.

I decided to push my luck. There was only one step left on the page. "Modify a grommet by squeezing it in a vise. There will be a distinct crunching sound when it is accomplished."

Now those of you who were with me when I attempted to mis-use a vise during the fabrication of the longerons will remember why this promised crunching sound didn't seem like a good idea. For those of you who weren't, consider this:

Vises are made for holding things, not squeezing things.

Still, Van's said to do it, so do it I did.

It turned out fine, but I'd be lying if I were to say that I didn't have a moment of concern at crunch time.

On my way out of the hangar, I remembered that I had promised to verify that a few mystery holes were supposed to have been filled with something by the time the firewall sealant was used to seal the firewall. Here's the picture of mine:

1 comment:

Torsten said...

Thanks for checking those pesky rivet holes in the paddle support brackets! I went right outside and filled them with LP4-3 rivets in all four, then open, holes.

Post a Comment