ZNLine Factory Enigma Build by Mark Novack

We use 7mm facing on both elevator and stabs. We will use wood glue. There is no danger of warping the piece with the wood glue due to the over width of the facing. We have a bit more to cut away when it is dry, but it keep everything in line and straight. Here are a few stabs and their elevators drying away. Next I will reduce the faces and ends on the rudders, then return to the stabs to plane down the faces.

I returned to the factory today, and removed the tail post blocking and clamps. I'll fill the minor gaps with a little epoxy and micro balloon, most of which will be sanded away when we bevel the fin post. Here is our unclamped fin post. The fin edge is perfectly straight and flat.

First, I very carefully fed the elevators through the band saw to cut away the excess. The stabs would not fit under the band saw feeder guide, so I sanded it down to about 2mm or 3mm on the belt sander. Same with the rudder. After cutting them down I started in with the razor plane and then finished by hand with my big sanding block. The tips I shall round down tomorrow when I am feeling refreshed. Here is the root view.

The pieces are not simply on display. I think that it is necessary for them to sit like this so that the air circulates evenly around the control surfaces. This will prevent any tendencies to warp from uneven climate exposure. Another couple of stabs, then I can move on the ailerons. Same procedure, just a little bit longer.

Well hello again. Many pressing projects and deadlines have come and gone in four days, but we are back to Project Enigma (it has a name now). In the last working post I had knocked the facings down level with the sheeting. The next operation was to even out the tips, a tedious job that looks like a minte's work but takes about five per tip. That done, the next step was to hinge. I will take a few more postings to show in detail how we hinge our ZN produced airplanes. Again, we are working for customers, so it must be not only perfectly functional, but clean and professional looking. One of these five airplanes, by the way, is going to fly in Poland at the World Championship this August. OK, enough background. We will be using nylon pinned hinges of 18mm wide. Here is a photo of the tools needed to perform the task of hinging with these hinges.

Tip to tip, set in our holder, and taped on the faces.

The tip hinge is 2cm from the tip (avoids the tip block), the root is about 1.5 from the root (is near where the horn will be). We mark our lines with a pencil using this little block as a guide.

Using the hinge, we mark inside. And voila, our root and tip hinge locations are established.

OK, I forgot to mention five hinges. Here, we measure the distance between the inside edge of the hinges. In this case it was 290mm. There will be three hinges and four spaces in that 290mm distance. So, pulling out the calculator, I take the 290mm, subtract the 3 hinge widths 3x18=54 so (290-54) and the result is 236. 236 divided by our four spaces between hinges is 59mm. So, each hinge will be placed an additional 5.9cm from the next one. I'll use this ruler and mark off 59mm, then 18 for the hinge width, then the next 59, etc, and all hinge locations will be established.

This tool is the Tettra slotting guide and as far as I am concerned, there is no better tool than this for properly aligning hinge slots. For you GP SlotMachine junkies, this would help you guide that saw nicely. For the plastic pinned hinges, I think this Dubro slotter is superior, especially with contest grade balsa. Like a hot knife through butter.

This next cut is quick and easy but nevertheless important. This cut provides clean ends for our next cut which will be the recess for the pin.

Note the tool I am using. This is a flat x-acto blade. The blade width is about .5". It is held at about a 40 degree angle and gently slides slideways from slot end to end and cuts away a little bevel. This is for the pinned portion of the hinge, but it has two other wonderful side purposes. First, it gives the perfect area in which to tuck the slit in the covering, and secondly, provides a wonderful trough in which to lay the epoxy. Whether one uses a thin epoxy like the stuff we use or a normal 50:50 epowy like Z-poxy or NHP, the epoxy will flow right into the slot. For the thicker brands, a touch of warm air from a heat gun or the spouse hair dryer will help if flow in nicely.

Lots of steps to arrive here.

Please notice the relationship between the slots. It's a first time fit using this foolproof method.

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