That pretty much does it for the wiring that I'm able to finish at the present time. There are still plenty of loose ends (literally! ha-ha!) but I need to work on some other areas first. My garage was becoming highly cluttered after a whole winter of electrical work, so I spent the evening cleaning and putting away stuff that didn't need to be out anymore.

Hmm, what to do with all these spools of aircraft wire?

A hardwood dowel and a piece of scrap lumber make a handy wire stand!

It's shocking how many little plastic containers of loose hardware I have floating around the garage:

It took me a couple hours, but I reclaimed about three quarters of it all, and put each item back in its little drawer. I still have a bunch of AN nuts and bolts, which I am not returning to the general population since I don't want an old beat-up fastener to accidentally be used for something important. Plus there's a bucket of miscellaneous parts that don't have a home right now.

Plenty of room for the next project now! Although I'm sure I'll have it looking like a pig sty in no time.

]]> http://www.rv7blog.com/2010/05/15/wiring-and-workshop-cleanup/feed/ 0 http://www.rv7blog.com/2009/08/10/how-to-crimp-bnc-connectors/ http://www.rv7blog.com/2009/08/10/how-to-crimp-bnc-connectors/#comments Mon, 10 Aug 2009 12:03:45 +0000 Matt http://www.rv7blog.com/?p=902 As I was making antenna cables, I thought it would be useful to show my method for crimping BNC connectors. The usual disclaimer applies: I am not an expert, I'm just showing you what I do.

I get my connectors from Aircraft Spruce, although you can find them just about anywhere. These particular ones are made by Amphenol and sell for about three bucks apiece.

Here's what comes in the bag… connector body, ferrule, and center pin:

One of the secrets is to use the right kind of coax stripper. The tool I use has three spring-loaded blades in it (kind of like my razor, I suppose). If you see one at your local hardware emporium, be sure to check the model number – all the ones I found in the local stores were configured for television coax cable. For stripping the RG-58/RG-400 coax we use in airplanes, the model 1255 is the one you want. I couldn't find one locally so I had to mail-order it, but it was comparatively cheap.

Since I'm a tool junkie, I experimented with different kinds of crimping tools. On the top is the "economy" racheting crimper sold by B&C for $40. On the bottom is an Eclipse frame with a set of RG-58/RG-400 BNC connector dies in it – cost for this setup is about $25 for the frame and $15 for the die, so it's basically a wash (prices are from Terminal Town where I bought mine). The dies on the economy tool are removable, and might actually be interchangeable with the Eclipse, but I haven't tried.

Here's a closeup of the crimp dies on both tools. On the left are the RG-58/RG-400 dies in the Eclipse tool, and you can see that there is just one crimp position for the pin and one for the ferrule. On the right is the economy tool, which can crimp multiple connector sizes. Either one works, although I find myself mostly using the Eclipse tool since I'm always crimping the same size of connector and it's impossible to get the pin in the wrong hole if you only have one choice. The other reason I prefer the Eclipse is that it makes a cleaner crimp on the pin… with the economy tool, the pin seems to get squashed flat a little more, so it's sometimes harder to get seated.

To cut the coax to length, be sure to use a real cable cutter, not a pair of dykes. The cable cutter has curved jaws that won't squash the coax insulation nearly as much, and it's cheap. These should be available wherever electrician's supplies are sold.

To strip the cable, clamp the stripper on the cut end using the illustration on the tool as a guide. It takes several practice runs to get the height-changing setscrews adjusted to give the proper depth of cut, so don't be afraid to use up a foot or two of coax getting your tool configured. To use the tool, use your finger to twirl it clockwise around the end of the cable (if oriented as it is in this picture) four times, then one turn counterclockwise.

If the blades are set correctly, you'll end up with (from left to right) a shallow cut through the outer insulation, a deeper cut through the braided shield, and a third cut that goes through the inner insulation.

With gentle persuasion, the cut segments should come right off and leave you looking at the untouched material underneath the cut. Take a minute to closely examine the cable for stray shield strands that might float around and bridge your two conductors together. You can leave the center conductor slightly long, since you'll probably be trimming it a bit anyway.

Slide the pin over the exposed center conductor. You want the base of the pin to be almost, but not quite, touching the white insulation. Trim the center conductor a bit at a time until it's the right length.

Squash the base of the pin with your crimper, and give it a tug to make sure it's secure.

Now slide the ferrule over the cable. If you're going to label it, now is also the time to slide on your heatshrink label.

Push the connector body down over the end of the cable until you feel a click as the pin is seated. The knurled bit on the back will dig under the braided shield. If you encounter strong resistance, can't get the pin all the way in, or don't feel the click, the most likely problem is that the crimper has deformed your pin enough to make it hang up in the connector body (see above).

When properly seated, the end of the pin should be flush with the end of the plastic insert inside the connector:

Without unseating the center pin, slide the ferrule down over the exposed shield. With the neato coax stripper I use, you should find that the shield has been trimmed to the perfect length and you don't have any stray shield strands poking out.

Now crimp the ferrule, and you're done.

I like to do a quick continuity check just to make sure the center pin isn't shorted to the shield anywhere. Antennas don't work very well with a shorted cable.

]]> http://www.rv7blog.com/2009/08/10/how-to-crimp-bnc-connectors/feed/ 0 http://www.rv7blog.com/2009/07/26/tail-weight/ http://www.rv7blog.com/2009/07/26/tail-weight/#comments Sun, 26 Jul 2009 17:00:30 +0000 Matt http://www.rv7blog.com/?p=858 I got tired of the fuselage swaying and rolling back and forth while I was leaning over the gunwales working on something, so I took out the tailwheel fork and built this rig… it's just a plastic bucket filled with concrete, with a dowel sunk into it.

In the middle of the concrete glob is the business end of a toggle bolt, and the dowel is drilled to accept the bolt and act as a guide. After letting it cure for a day, I ended up with the world's heaviest nutplate.

To dress it up a bit, I cut a disc out of some scrap particle board.

Another piece of drilled dowel goes on top, and the tailwheel fork slips over it.

I made a wooden washer and bolted the tailwheel fork into the bucket of cement. It's now so secure that it might as well be anchored to the floor. I don't know why I didn't do this a couple years ago.

]]> http://www.rv7blog.com/2009/07/26/tail-weight/feed/ 0 http://www.rv7blog.com/2009/07/04/adi-wiring/ http://www.rv7blog.com/2009/07/04/adi-wiring/#comments Sun, 05 Jul 2009 02:00:11 +0000 Matt http://www.rv7blog.com/?p=809 I can't afford a real two-inch standby attitude gyro (they cost a mint… and I'm talking this kind of mint, not this one) so I have a TruTrak ADI instead. It's not a real attitude indicator, but it should be good enough for a backup instrument. And since it's a safety-of-flight item, I wanted to make sure it was fed by dual power paths, as are the other most important avionics in my panel. Unfortunately TruTrak didn't provide dual diode-isolated power inputs like Garmin did, so I had to use a pair of 1N4001s to create my own:

Heatshrink tubing protects against shorts – after I took this photo I added another piece, then crammed the whole assembly into the D-sub backshell. One side is fed by Bus 2, which powers my important avionics, and the other side is fed by the standby battery. This arrangement will also keep the gyro alive while cranking the engine, which might be a good thing considering some of the funny behavior Matthew reported when he had his ADI powered on while starting.

Here it is mounted in the panel… I verified that it powers on, figures out which way is up, and receives GPS data.

Port-side view of the ADI wiring harness. The D-sub connector comes pretty close to the panel, but there's enough room to avoid kinking any wires. However, it would not have fit if I'd mounted it in the center standby instrument hole as I'd planned, which is why I moved it to the top.

"But I thought the ADI wouldn't fit in the top hole!" you say, or at least that's what you might say if I allowed comments on this blog, which thanks to the efforts of spammers I don't, thank you very much spammers. "You even posted a photo of this exact thing!" you might also exclaim if I let you. Well, yes, but that was before I figured out that a UMA light bezel inserted ahead of the instrument spaces it back far enough to clear the panel frame:

So thanks to the light bezel the ADI now lives at the top of the stack of standby instruments.

This is actually great news, because I was already planning to use UMA light bezels for my standby altimeter and airspeed indicator, and I was bothered by the fact that the ADI's internal lighting didn't match them in color or intensity. So, I broke out my Fluke and did some probing around… It turns out that I was able to defeat the ADI's internal lighting by connecting the 5V output pin on the dimmer unit to the ADI pin that's designed to be connected to a 24V lighting bus. What happens is that when I turn on the nav light switch, thus energizing the dimmer, the ADI sees five volts on its 24V lighting input (equivalent to 2.5V with a 12V lighting bus) and reduces the brightness of its orange LED display… but 5V isn't high enough to turn on its internal lighting, so I'm free to use my light bezel to light the instrument face instead. The dimmer potentiometers don't care about the extra milliamp or two that the ADI sinks on its lighting input pin. Excellent.

If you're still awake after reading the above paragraph… yes, I can be a huge geek sometimes.

This was the first time I'd seen the full interior installed at the same time the panel was all powered up. Looks nice.

There are a few things visible in these photos that I haven't documented on the site yet, but I'll get to them soon.

Of course a lot of what you see here is still yet to be finished, but it was neat to see so many things looking "done" at once. One might even think, looking at these pictures, that it might someday become "actually done".

Mary here, talking to all of you who ladies whose husbands have said, "Honey, I want to build a plane in our garage."  You're understandably freaked out right now – I was when I found out that building airplanes is one of Matt's favorite hobbies.  Don't fret!  This is a doable project!  However, you shouldn't go into it blindly.  Here are some things to expect from an airplane-building husband.

This is a huge endeavor. OK, you probably already figured that out.  But let me give you a little perspective.  Matt began building the plane in Spring 2005.   I started pharmacy school the following fall.  I graduated this month, but Matt's plane is still a year away from flying.  This is not for the flighty (no pun intended).  This is like having a baby.   The plane will be a major part of your lives for years, if not the rest of your life.  (Thankfully, there are no 3 AM feedings.)  And much like a baby, a plane will require you to invest a good deal of money and space.  Consider:

1. You'll need workshop space.  For a lot of you, this means you'll have to give up parking in your garage.  You also might find an airplane canopy on your guest bed, or ailerons in your spare room.
2. It gets expensive.  Builders need rivets, rivet guns, clecos, pliers, drills, screws, an air compressor, wires, deburring tools, wrenches, countersinks, fiberglass material, hoses…  It adds up, and will continue to add up throughout the project, as he'll need to get more and more stuff. The UPS guy and I are pals.
3. As I mentioned above, it takes a ton of time.  If you want to be at his side 24/7 either be prepared for him to never finish the plane or go out and help him. Which brings me to my next point…

Building an airplane is not just something for him to do.  This can be a family project. You don't have to be out there every second – despite what the pictures on Matt's blog might suggest, I'm not out in the garage every time he is.  It will go a lot smoother if you get involved.  There are certain tasks that are a lot easier to do with a second pair of hands, and everything that gets done puts you a little bit closer to flying.  Even going to the workshop for a few minutes to look at the neat new thing he built can be a big morale boost.  And men, this is a two-way street.  Make a deal that for every, say, 30 minutes, your wife spends on the plane, you spend that much time on something she likes, or do some of the household chores for her, or stay home with the kids while she runs errands.  And speaking of kids, they can help too.  But use your good judgment; letting your toddler handle a rivet gun is probably a bad idea.

You'll meet a lot of new people in this process. Your husband will probably make friends with other builders through VAF, the EAA, and local airports.  Take advantage of this! For one thing, it gives him someone else to talk shop with when you get sick of the airplane stuff.   For another, a lot of these guys are married too, and you and the builder's wives can commiserate.  Airplane people are some of the nicest, most interesting people you'll ever meet.  Far-flung airplane pals can also tip you off to places to visit on your next vacation and maybe even get you a free lunch somewhere.  (Thanks Doug!)

You need to be his #1 cheerleader. I'm not asking you to put on a short skirt and wave pom-poms [aww. -ed.] unless you enjoy that sort of thing, [woohoo! -ed.] but airplane building can be a frustrating process, and your husband probably won't enjoy every part of it.  (See also: Matt and fiberglass)  Help keep him going during the difficult parts.  If you can't help, come down and talk to him while he builds, or let him bounce ideas off of you.

You may also need to keep him on task. Again, not every part of this is enjoyable, and it's easy to get discouraged, especially for someone who has a demanding job.  He may, like Matt, suddenly think it's more important to work on one of his other projects than the plane.  While sometimes that's necessary (the plane can wait if Junior needs help with his science project), too much of that can mean he loses momentum and before he knows it, he hasn't worked on the plane in a month.  Planes that don't get worked on don't get done, and we want these planes to get done.  I once had to threaten Matt with no slushes for the rest of his life if he didn't give up his extra projects and just focus on getting the plane done.

And finally, have a sense of humor. So your friends all think you're crazy, you can't walk into your house without tripping over a just-delivered box of parts, and your guest room looks like an obstacle course.  So what?  You and your spouse have a fun (hopefully) relationship-strengthening project you can do together, and even if you're only minimally involved, you always know what he's up to.

She's been working a whole heck of a lot harder on her education than I have been on my airplane. That may have something to do with the reason why she got done first, and she definitely earned it.

And yes, the girl in the background does have a giant pill on her head.

We also found out this week that Mary did in fact land the postdoc residency she wanted – it's close enough that she'll be able to commute from home, which means we won't have to worry about moving for another year or so. Still, I need to hurry and get this thing finished before the clock runs out!

We still have the molds from last year, so all we had to do was melt up a whole bunch of chocolate chips:

We have two molds, and we can do a full casting cycle about every 40 minutes. In between is TV and video games.

Half are plain, and half are crispy:

He should be quite delicious… if he survived the freezing process, that is.

Another beauty shot of Mary modeling Chocohan. I'm telling you, this version of Valentine's Day is way more awesome than what they show in jewelry commercials.

During the course of the day we made two dozen Chocohans. Also, our fridge has a lot of booze in it. Who's to say whether or not these two facts are related?

We now return to our irregularly scheduled airplane blogging.

In 2005 Jerry and I flew his Super Decathlon to Idaho and back, a trip of 3000 miles in a single week. We went into a lot of the back-country strips and high-altitude airports, and he taught me a lot about taildraggers and mountain flying. The memories from that trip are ones I'll never forget.

Then the next year we went to Florida together to earn our seaplane ratings, which was another unforgettable experience. He got a real kick out of flying a J-3 Cub off the water. I remember we went to this really terrible fish restaurant one night to prepare for the oral exam and checkride, and spent as much time laughing as studying.

Mary and I had planned to spend last weekend at his place in the Ozarks, but I begged off at the last minute because I was tired from getting over a cold. Now I wish I'd gone anyway, but I'm glad I at least had the chance to talk to him a couple times this week.

Jerry was a teetotaler, but you can bet I'm having a drink for him tonight. He was one of my heroes and I'll miss him.

Sorry for the interruption. I promise the next post will not be such a bummer.

Then I gave them to a friend from work, who very generously ran them through his laser and engraved labels for the switches right onto the wood. It turned out looking great:

The passenger's stick has a push-to-talk (PTT) button and a four-way trim switch. The pilot's stick has switches for PTT, trim, autopilot disconnect, and engine start. Yes, I am putting a start switch on the stick… with a fuel-injected taildragger, you normally need three hands to start the engine: one to turn the key, one to monkey with the throttle and mixture, and one to hold the stick back to keep the airplane from going over on its nose. Since I'm not a Hindu deity I can't manage this very easily, so I will put the starter control right on the pilot's stick grip. There will still be a key switch in series with the button for safety, so you won't be able to accidentally engage the stater if you bump the stick with your soda.

Okay, it's possible that I may have a tool addiction.

It does a great job of crimping the little machined pins used in D-sub connectors, though.

]]> http://www.rv7blog.com/2008/09/02/new-crimper/feed/ 0 http://www.rv7blog.com/2008/06/10/woodworking/ http://www.rv7blog.com/2008/06/10/woodworking/#comments Wed, 11 Jun 2008 02:36:42 +0000 Matt http://www.rv7blog.com/2008/06/10/woodworking/ I haven't worked on the airplane in a little while, but I have been keeping busy with other things. For example, we finally broke down and bought a new TV to replace the third-hand 27-incher I bought from a guy at work for fifty bucks many years ago. However, I'm too cheap to pay hundreds of dollars for a simple stand to set the new display on, so I decided to build my own.

Woodworking is not my forte, but I managed to put together a pretty decent looking cabinet out of laminated pine planks and a sheet of birch ply for the back. It took me about three evenings to get all the pieces cut, fitted, and sanded, and then Mary and I spent half a Saturday putting it all together. The top is attached with Miller dowels for a smooth finish.

I've built plenty of workbenches, storage shelves, and sawhorses in my time, but never anything that actually had to look good, so the wood-finishing process was new to me. I was worried that the low-quality pine I used wouldn't take the stain evenly, but after a coat of pre-stain sealer and a coat of oil-based stain, it looked pretty darn good:

I let it dry overnight, and then applied the first coat of clear varnish. Almost immediately I could tell something was wrong… the varnish started moving the stain around! Arrgh. The varnish topcoat went on okay, but it seemed to somehow soften the stain and cause blotchiness. Either the stain wasn't all the way cured, or perhaps the wood really is of such bad quality that the stain didn't really soak in. Oh well – I'll just tell people it's a "distressed" finish. I was pretty distressed when I saw it.

I sanded the first coat of varnish with 400 grit, then put two more coats on over the next couple days. I sanded the final coat with 800 grit crocus cloth for a nice smooth finish. So here's the final product – my old stereo stuff will go underneath, and the cables will pass through the holes in the back:

Overall it turned out pretty good, except I'm pretty disgusted with the finish. The total cost was under a hundred bucks, not including the value of my time. If I had it to do over again, I'd probably make it out of something better than pine – oak, maple, maybe something else? – and be more careful about the staining process. I'll probably also use a semi-gloss topcoat next time, instead of satin.

Well, that's done. We now return to our regularly scheduled airplane building.

To keep the inner lining from soaking up oil and moisture, which would ruin its fire-resistant properties, it's necessary to dip the cut ends of the firesleeve in some kind of waterproof substance. There is a genuine aviation-grade "end dip" that's used by certified shops, but it sells for the outrageous price of $117.95 a quart! No way am I paying that much. So, I figured there were basically two readily available substances that could be used as a homebrew firesleeve end dip: Plasti-Dip and plain old RTV

In the interest of science, I procured a container of each and used the products within to treat the ends of a pair of two-inch lengths of firesleeve. After letting them cure overnight, I evaluated the results. The Plasti-Dip (on the left in the photo below) was more brittle than I had expected, and developed cracks when the firesleeve was flexed gently. The RTV remained slightly rubbery, as it is wont to do, and the end of its test piece remained well sealed after the flex test. Advantage: RTV.

Then I got out the matches and started burning stuff. When exposed to direct flame, the RTV became charred and began to emit a small amount of smoke, but would not ignite. This seemed like appropriate behavior for the end of a piece of firesleeve.

The Plasti-Dip sample, on the other hand, caught fire quickly and burned like a candle until I snuffed it out:

Conclusion: I will treat the ends of my firesleeve with RTV, and leave the Plasti-Dip for the occasional screwdriver handle.

Showing off the panel to my dad:

Mary, me, and my brother:

]]> http://www.rv7blog.com/2008/03/08/family-visit-2/feed/ 0 http://www.rv7blog.com/2008/02/27/rivet-insanity/ http://www.rv7blog.com/2008/02/27/rivet-insanity/#comments Thu, 28 Feb 2008 02:25:55 +0000 Matt http://www.rv7blog.com/2008/02/27/rivet-insanity/ Sometimes Van's sends me a bag that contains two different sizes of rivets, which I then have to painstakingly separate so I can put them into the right storage drawers. This time the two rivet sizes were only 1/16" apart, which made it an even more eye-crossingly tedious chore.

I think they do this to me just so I won't get cocky.

In exchange for first dibs on the finished product, Nick provided a frozen-Han action figure. I felt momentarily bad about opening the still-sealed packaging, but there's science to be done!

I used my belt sander to take off the protrusions around the edges, and sanded the sides down to 400 grit. Some people who are even bigger nerds than me have documented the function of the bits I removed – I hope Han does okay without a functioning carbonite flux monitor.

While I prepared to start making the molds, Mary gave Han a bath and toweled him off.

I used two pounds of silicone plastique, a two-part, food-grade moldmaking compound.

When mixed, the silicone has the approximate consistency of silly putty, but is demonstrably less silly. Mixing is done by hand.

I formed the silicone into a brick shape, and pressed Han face-down into it.

After letting the silicone cure for several hours, I carefully popped him free, and was left with a nearly perfect Han Solo mold. Success! With the remaining silicone, I then made a second mold using a similar process.

To melt the chocolate chips, we placed them in a metal bowl suspended over a pot of hot water, as recommended by the confectionery experts.

The melting process must be done slowly, lest the chocolate be singed by excessive heat. Patience!

After liquefying the chocolate, we carefully spooned it into the molds and placed them in the freezer to cool.

After a half hour, the chocolate was well and truly solid again. I pried the finished products from the molds, and we were rewarded with a pair of Chocohans! One of them seems to be missing his face, but there's no use crying over every mistake.

Mary doing her Barker's Beauties impression with a lucky Han Solo:

We kept on going until we ran out of chocolate – two pounds of chips was enough to do six Chocohans. Once we refined our technique, we decided to get crazy and make a pair of Crunchy Chocohans by adding Rice Krispies after pouring the chocolate.

I wrapped the Chocohans in aluminum foil and took them to work, where they were a huge success.

Disclaimer: While I do claim to have come up with this idea independently, the historical record will show that at least one intrepid culinary artist had already beat me to it. Still, this was a triumph! It's hard to overstate my satisfaction.

As is usual when I go to Harbor Freight, I couldn't resist buying something cheap that I didn't really need – this time it was a drill press vise for nine bucks. And, as is typical, it's really crudely made. I followed John's advice and replaced the rusty, jagged steel jaws with thin strips of wood, which makes it way more useful for holding aluminum airplane parts.

]]> http://www.rv7blog.com/2007/09/29/support-your-local-imported-junky-tool-store/feed/ 0