Now the plexiglass can be cut to fit the window frame. The aluminum strips were removed from the window frame. Then the plexiglass was placed on the table top and the frame was placed on to the plexiglass. Using a Sharpie marker, the inside of the window frame was drawn onto the Plexiglass.
The Plexiglass was then carefully cut out using an air dir grinder with a cut-off wheel. I find that this is the best way to cut plexiglass as sometimes a saw will cause little stress fractures in the Plexiglass.
The plexiglass was notched at the door lock bracket location to fit around it. After cutting, the edges of the plexiglass were smoothed with a vixen file and then a fine file.
The plexiglass window was then inserted into the window frame and the 1/2" aluminum angle pieces were clamped in place holding the Plexiglass in. 3/32" holes were drilled with 3" spacing through the angle, plexiglass and the outer aluminum skins, clecoing each hole before drilling the next.
Here is window with the Plexiglass installed and intial drilling completed:
Once all of the holes were drilled, the angles and plexiglass were taken apart again. At this point all holes have only been drilled to 3/32". Now the holes in the aluminum angle and the window outer skins will be opened up to 1/8" and the Plexglass holes will be opened up even larger to 3/16".
The Plexiglass holes must be drilled out to be at least 1/16" larger than the aluminum angle and skin holes. Drilling the holes oversize, allows for the natural expansion and contraction of the Plexiglass within the frame. The Plexiglass will expand and contract in response to heat and cold. If you don't oversize the holes a bit, you have a good chance of experiencing some cracking of the window around each hole later on.
Caution: Avoid using a regular drill bit to
open up the holes in Plexiglass. A regular 3/32" bit is
okay for the initial drilling of the hole, however you may crack the Plexiglass
if you try to open the holes up with a regular bit. They make special drill
bits for Plexiglass, however I have found that the best bit for Plexiglass
is a Unibit. I used the small Unibit (that goes from 1/8" to 1/2")
opening the holes to the second step on the bit which is 3/16".
The trick is to keep the drill bit turning at fast speed, but move it
slowly and steadily into the material until you have the correct size
hole.
After opening the holes, they can be deburred with a regular deburring tool,
using light pressure:
In the picture above you can see the notch that I had to cut in the Plexiglass
to clear the locking bracket on the door frame.
Now it can all be assembled. For ease of assembly, I simply used 1/8", all aluminum Pop Rivets. These are easy and quick to install, and if you ever need to replace the plexiglass later on down the road, the all aluminum (both the rivet and the mandrel are aluminum) Pop Rivets drill out very easily.
Here is the completed side window on the pilot's side:
As you can see, we have a nice tight fit all the way around. Yes the Plexiglass
is in there, it's just very clear.
Here is a picture showing the key lock and handle detail:
The window skins were cut to create a 1/4" overlap on both sides and at the
bottom. The top has to be cut to be just about even with the top of
the opening in the fuselage because it hinges at the top.
That's it for now. When I return, I will have completed the other front window (Passenger side) as well as the rear "D" window installation.
Come
back later for more . . This page was last updated on April 15,
2007.
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