This week was about finishing the rear windows and starting on the windscreen.

The  process for the rear windows is about first getting close to the scribe line with a Dremel tool. Then using 120 grit sanding belt before hand shaving closer with 220 and polishing/rounding the edges with 320 grit.

For the windscreen first peel back the protective covering just enough to expose the previously marked scribe line.

The windscreen is a slightly different process, as it is much thicker (roughly 1/4″ Lexan or acrylic).  My technical counselor advised against using a Dremel tool, saw or other cutting mechanisms (tend to cause cracking in this type/thickness material).  Instead a 3″ belt sander with 80 grit paper is used to get close. Everything else is by hand.

When talking about ‘by hand’, I mean hours of edge sanding with 80 grit paper on a Great Planes sanding block. Going through Lexan this thick takes time. Check for fit, mark the high spots, and repeat over, and over, and over…

The hand shaping process requires many iterations, but this way has less danger of removing too much, too fast in the wrong places as with power tools.  The final outcome is coming into shape nicely.  More of the same fitting process this weekend before the edge polishing can begin.

Attaching the center console brace and beginning to trim window panes was the order for the day.

The center brace is clamped in the middle of the forward canopy cover, then match drilled with a #12 drill to accommodate an AN3 bolt.  This is tightened down to fasten the brace, so the the rest of the holes can be drilled.

Here is how the top of the outer cabin cover looks after the fastener holes are completed.

Here are left/right pictures of the bottom portion of the center brace attached near the firewall.  Two AN3 bolt hole are drilled between an angle bulkhead and a reinforcing plate.

A set of spacers 1-13/32″ long  are fabricated from 5/16″ diameter tube.  This will eventually be driven into enlarged holes for the center brace.  The cabin cover needs to come off for further processing, so this step will be saved for later.

The plans call for fitting the windscreen first, but I wanted some experience dealing with Lexan/acrylic trimming beforehand.  The side windows will be my test platform – if things go south these will be cheaper and easier to replace compared to the windscreen.

Pull back the protective covering and get ready to power trim!

Over the Thanksgiving week off the focus was finishing major elements of the cabin cover.

The first step was complete match drilling the mid-skins to the cabin cover.

Next was clamp the rear door frames to the bulkheads and match drill for #10 countersunk screws.

Here the right side has been drilled and clecoed into place.

Now for the forward door frames. The gusset  is clecoed to the bulkhead, but match drilling for the #10 screws to the fiberglass frame goes through about 1/4″ of empty space. According to the plans, this space will have structural filler applied.

Getting the fiberglass trimmed for the front deck took quite some time. (between initial Dremel tool sanding and hand filing).

Next was measure the door jam bottom, then drill #19 holes for #8 countersunk screws.

Check for size, then countersink with an angle tool.

The final product looks pretty good.

Now rough fit the center console brace.  Overall starting to look like an airplane.

I had another forced pause from the shop due to business travel overseas.  This weekend was getting back in action with Eric’s help on further cutting, fitting and sanding the fiberglass cabin cover.

The door bottom needs extensive trimming to get to the proper thickness.

Left and right sides need to be notched to accommodate the bulkhead reinforcements at the bottom.  Notice the degree of relief needed to make this fit.

The inner section must line up just right with the mid-skin longerons.  Too much taken off will decrease strength for the connecting rivets.  Too little and the fiberglass bottoms out on the longeron and fit will not be proper.

First reduction was with a fiberglass cutting wheel on a Dremel tool, followed by a belt sander, hand file and finally Great Lakes 22″ sanding block with 120 grit paper.

Fit, trim and refit is the process here. Getting the cabin cover to slide in without too much material removed takes time and patience.  On the right photo the 3/4″ offset for windshield and doors are being highlighted with a Sharpie.

Trim the windshield flange…

Clamp the rear door pillar and bottom flange in place.  Then start the match drilling of the cabin cover to the top tailcone skin.

Eric pushes up on the cabin cover fiberglass while I drill #30 holes down through the tailcone skin. This process will continue on around the whole baggage bulkhead area.

The weather forecast called for beautiful skies and temperatures over the weekend, so I enlisted Eric’s assistance in starting to trim and fit the cabin cover to the fuselage. The idea is get everything aligned properly, then finish the interior metal painting.  This way scratches produced during the fitting process will be reduced.

Faint scribe lines are on the fiberglass mold from the factory, but difficult to see under most conditions.  I added electrical tape along the edge for a better visual reference when rough cutting with a Dremel tool.

The process is easy, but takes time.  Rough cut near the scribe line, then hand sand until smooth.  Then fit on the plane and continue sanding until everything lines up perfectly.

Here is a closer look at the rough out process.

A long wooden dowel is attached to a 22″ Great Planes sanding block.  Eric guides the dowel along the opposite end while I smooth sand and get closer to the the scribe line.  The dowel extension will approximately make the surfaces parallel on both sides.

The first rough fit shows additional material needs to be removed. Sand and refit until alignment is correct.