Inserts and Hinges

Step 4 INSTALLING THE NC-6 INSERTS AND THE NC-3 HINGES IN THE CANARD

While I waited for some fiberglass to come in from Wicks for some steps on the MLG strut and elevators, I worked ahead a bit and made some of these jigs I would need. I started with some plywood and prints of the M drawing parts I needed to make. I decided to try to make all 4 templates L in one shot. We'll see how it works out.

The band saw makes quick work of most of these templates. I scan them, print them (checking size to match, of course) then spray glue the pieces I need onto the plywood I'll use. I then rough cut them to shape, leaving 1/16" or so and then use a sanding belt in the band saw to sand them to exact shape.

For the 4 templates L I needed to make, I glued the drawing to the top piece of plywood then clamped the 4 pieces together. Using the drill press, I drilled a bunch of 1/4" holes and then inserted dowels into them to hold the 4 pieces aligned while they were cut and sanded.

I did basically the same thing with the 2 templates J I needed to make but in this case because the pieces were odd sized I drilled a hole, inserted a dowel, drilled the next hole, then repeated that a third time.

Once the L templates had been drilled and doweled, I then cut the pieces out, slowly and carefully 'cause it was by then a big stack and pretty thick.

After sanding with a sanding belt to shape, I had 4 identical L templates. Awesome! Knock the dowels out, label them and they're ready for use.

Here's the whole set of templates, after cutting and sanding. I did use aircraft quality ply for the airfoil templates H and I since they need to be quite accurate. I used CDX 3/8" plywood for the rest.

Try making your flox corners like this. Run the edge of the bit, just below where it has "teeth" along the edge of the cured fiberglass along the edge. Set the angle against the edge to determine how deep to cut, then run the bit along the edge to get a nice, even, straight, cutout for the flox corner.

I did my elevators via vacuum bagging, so I still needed to do the trailing edge micro treatment following the curing of the top skin. I figured if I put some blocks under the elevators, and did the ends carefully, I could do both ends, then apply the trailing edge treatment all at the same time. Here's my setup. I mixed up some flox first, so it would thicken up/cure just a bit while I did the 1 BID layup (seen between waxed paper at the other end of the jig table) to help prevent the end layup from falling off when I did the other end of the same elevator.

Some people have suggested syringes for flox and micro, but, plastic bags work better. This is a Ziplock® bag, but, given that I usually just twist the flox or micro into a corner, you can use any sort of bag. Here I am using one to "pipe" flox into the flox corned on the end of one elevator before adding the 1 ply of BID.

Here's the 1 BD ply going on. I added a bit more flox than I needed, and, the flox oozed out into the center of the torque tube and around the edges of the top and bottom skin. I figure most of this will sanded off anyway, so, no worries here.

Here's both elevators, with both ends microed (just the center where there's no flox), the flox corner and the 1 ply of BID. I also then did the micro/peel ply trailing edge treatment and left them to cure. I usually don't try to do too many steps at once like this, since I usually screw up somehow when I do. This combination seems to have worked fine, however.

Ha! I ALMOST messed this up! But I didn't! Ha! I was laying in bed, thinking about how I would have to dig out some foam to install the bolts that bolt the inserts into the elevators - but how would one do that with fiberglass over the end! Oh no!

Run downstairs and removed the single layer of BID (it had only been curing for an hour or two, so it came right off. Cleaned out the flox and heaved a big sigh of relief. Hey - look on the bright side - I already have the flox corner cutouts ready!

Once that fiasco was over, and the ends had cured, I started on the NC-6 installs. I marked and drilled for the #10 hole before I installed the NC-6. This would prevent any risk of damage to the NC-6.

Here's the insert, after installation, with the hinge pin in to line it up and the Cherry rivet before pulling. I think that a shorter rivet would be easier. However, if you go slow and push the head in further each time you squeeze to pull the rivet, it ends up flush and all's well.

Time to make the spool piece. I'm not sure why, but, I have two pieces of tubing with which to make this. I ended up using part of only one, here I am measuring the right spacing on the hinge slots in the CZNC-12A pieces. I noticed that my CZNC-12A pieces didn't look right when I got to this step. Checked with Nat, yep, one of them is cut wrong, all is right except for the hinge slot, it's about 140 degrees off. I'll have to get that replaced, wish me luck.

I used my belt sander to fine tune the length of the spool piece. Mine ended up needing to be just a hair over 30 inches, say 30.04. With the square and the deck on the belt sander, adjusted square, I get a nice, square, even end on tubing. Test fit, too long. Sand a little more. You get the idea.

Once the micro on the trailing edge was cured good and hard (it was a little rubbery earlier in the day) I clamped the elevators to the end of the jig table with scraps of foam left from hot wiring the cores. I then used my spline sander to fair in the trailing edge to the right shape. Turned out great. I'll need to final sand them before finishing, but, they're ready for further construction.

When I started to assemble the spool piece and the CZNC-12A pieces from Brock, I quickly realized one of my CZNC-12A parts was made wrong. I know lots of people give the folks at Brock a hard time, but, even after ordering this part several years ago, I sent it back and they replaced it - no charge. Now that's what I call service!

Once the new CZNC-12A came in, it was time to get building again. Here's a shot of drilling the #12 holes for the AN13A bolts that hold the spool piece to the CZNC-12A. I have a piece of wood weighted down holding the two pieces in place and I've already drilled the pilot hole with a #30.

Once the spool piece was made, I jigged the elevators per plans with 6" pieces of wood hanging 1" off the edge of the table. I leveled these to 0 with my Smart Tool, for most of them I used 2, 3 or 4 pieces of printer paper. I then weighted the elevators down to keep them from moving. I also hot melt glued (I don't use any bondo, per plans, it takes too long to mix, is too hard to get off and takes twice as long as hot melt) some wood blocks to the edge of the table. These I used a square against to make sure the elevators were in line since the edges of my table are straight. I did wish I had save the leftover foam from hot wiring the cores, those pieces would have been handy here with weights instead of having to use towels.

I made a wood jig to set the CZNC-12A pieces at the right angle as compared to the bottom of the elevators.

Once the piece was made, I placed it on the table, weighted down, then pushed it towards the CZNC-12A and rotated same until the jig fit snugly. Now my spool piece and CZNC-12As should be at the right angle as compared to the elevators. Don't worry - the wood piece here was at 0 before any leveling - so there's no difference between the table and the elevator bottom....

Once the horizontal holes were drilled through the CZNC-12A parts on either side, and some foam was removed to be able to get the nut and wrench on the other side of the bolt, my daughter Emily decided she wanted to help. I gave her the wrenches and she installed the bolts for me. She also helped in the next step, where you insert the NC-3 hinges and AN960-10L washers with the hinge pins. Her little fingers made quick work of installing the washers on either side of the NC-3 pieces as the hinge pins were installed. Thanks, Emily! By the way - if you haven't heard this trick - use a cordless drill on the end of the hinge pins to twist it as you insert them. You can turn the drill slowly forwards and reverse as well as push on the drill without bending or scratching the rod, and, the rotation helps the pin go through without binding.

Here's a shot of the elevators jigged onto the canard with the L jigs. I ended up with a bit of a gap, between the L jig and the aft portion of the canard. I guess my trailing edge is a little long/too low or my canard are a bit fat. I sanded the trailing edge with my spline quite a bit, and, that did the trick. No gaps between the L jigs and the bottom of the canard. I also made sure the elevators were pushed forward into the groove as far as they would go, and, the L jig was pushed forward as well. This seemed to help things fit better.

The trailing edge is indeed flush with the elevators at the full trailing edge up condition.

Marking the canard for the 1/4" slots for the NC-3 hinge pieces. Once I had marked their centerlines, I used a square against the edge of the table to mark where the slots would go.

I drilled both ends of the slots with a 1/4" drill. I found that the routing step was easier, as described in the plans, if I drilled the foam straight down in several places before trying to use the drill bit as a router.

I also used my Fein Sander for these slots. I have an attachment for it that lets it mount very skinny saw blades, like this one, with teeth on the end. Perfect for cutting slots like this one through a few layers of fiberglass.

Here's one of the slots after cutting the edges with the Fein, drilling the foam in a few places, routing with the drill bit then vacuuming out the leftovers. I used the plans drawing to located the bottom edge of the slot, measuring 1 1/2" up from the trailing edge to make sure I had enough room but not too much which would let the flox spill out in later steps. The top limit of the slot is parallel with a line than runs along the aft edge of the spar cap.

After the slots were cut, the elevators were jigged on again in the right place and fixed in place (I use hot melt - bondo smells bad, you have to wait for it to cure and it's a pain to get off when it's cured) I floxed in the NC-3s. You can see part of a credit card here, wedged in place between the canard and elevator, preventing the NC-3 from falling down into the slot too far as the flox cures. This is one of these steps that you check and check and check and check - then walk away and let things cure - and hope all is well when you come back later....

That's as far as I have gotten on the elevators.