Wednesday, May 18, 2011

A Day for Foam Cutting...

Last steps before glassing the sides.  I had to dish out extra room for the stick and the fuel gauges.  I already had them marked, now to figure out how to dish out the necessary foam neatly and accurately.  So I thought...I don't have a router, but I do have a Dremel tool.  I just need to make a tool to control the depth of the cut.  So I used a small piece of wood with a hole in it large enough for the cutter but small enough the hold the Dremel tool up.

We'll I managed to screw that up.  Let's just say my impromptu tool wasn't as good as the concept.  It was very uneven and I even went all the way through the foam in two places...a very bad job.  I ended up cutting a complete new circle of foam from my scrap and replacing it with 5 min epoxy for a fresh start.  Now what?  Then it occurred to me that they must make a similar tool (that works) designed specifically for rotory tools...sure enough...Lowes, $15, a Dremel cutting set with a depth gauge and 3 cutting bits.  It even fit my 25 year old Dremel tool.

This tool (above) plus a wider radius cutting bit than the ones that came with it made quick work of removing the foam to the proper depth.  I just sanded down the edges to allow the glass to lay down and I was done.

I used the same thing on the areas for the fuel sight gauges.  The Vance Atkinson Gauges are an addition to the plans version which is just a simple glassed window.  I went ahead and followed the basic plans approach but made the area flat instead of beveled since the Atkinson gauges can be seen from 180 degrees.  I made the cutout .5" longer than the gauge to allow for adjustment when installed.  You want to put the bottom hole of the gauge as close to the bottom of the tank as possible which according to the plans should wind up at 8.7" down from the bottom of the longeron.  We'll see in a few Ch. 21 this area will be opened back up from the inside, the foam removed up to the outer skin, and the gauges installed per Vance's instructions.

The picture above also shows the channels for the electrical conduits back to the firewall that I also cut today.  After reviewing the Cozy FAQs from Marc Z's page, I put them 14.7" down from the top of the fuselage side vice the 14.5 in the plans to avoid running into the pulley assembly in the firewall.

Now then, ready to glass the interior of the fuselage sides after one more thing...checking the fit of the longerons.  I laid them into the appropriate place, lined them up appropriately, and viola, they seemed to fit nicely...just a little weight in the center when epoxied in place will help ensure they mold perfectly to the sides.  The only thing that worried me was how to make sure the alignment was good and each fuselage side was identical.  The foam and spacers had enough tolerance build up along the edges that the gap between the two sides had some variation in it.  If I lined up the longerons assuming they needed to be lined up with the edge of the foam, they may not come out flat or level with the fuselage side  What to do....I know...another tool!

Tip:  The plans actually call for you to use a 7/8" wood spacer.  Withe the glue that's oozed out under the foam and the minor variations in the foam as it was built up, a board that goes all the way down to the work table wasn't going to work correctly.  My version of this tool not only allowed the gap to be accurately maintained but was also self supporting...resting on the longerons themselves...and didn't extend beyond the bottom of the longerons which allowed me to place them accurately regardless of the foam situation underneath.  See the picture but basically it is just a piece of 2x4 cut with a 7/8" T section, and cut into 4 pieces so I can spread them along the longeron.  I already test drove these and they work great.  I can ensure the gap is correct and by taking measurements from the longeron to the bottom of each side, I can make sure both sides match perfectly.

Now it's time to glass.


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