January 20, 2007 -  The Big Cut

 
With my triangular file, I smoothed the flush pop-rivets on the aft part of the roll bar.  This is so the canopy won't get scratched.
OK, so how do you know where to make the big cut.  With the canopy on the fuse, with a thick Sharpie, I drew a line on the clear vinyl where the middle of the roll bar was.  Then I took the canopy off and cut the vinyl apart with about a 3" gap with the approximate cut line in the middle.  This was a lot easier said than done.
Then I put the canopy back on in proper position, and with a fine Sharpie, drew the exact cutting line on the Plexiglas itself.  With the canopy still on the airplane, I laid masking tape on each side of the cutting line with about a 3/32" gap.  I put three layers of tape on each side.  Hat tip to Dan Checkoway. 
The idea is that the cutting wheel will be guided by the gap in the masking tape.  I put the canopy on 2x4s with blocks clamped at each end to keep the canopy compressed to the proper width.  I had the heater underneath getting the canopy nice and warm.
I used a box, paint can and foam to support the canopy rear.  I tried hard to anticipate what was going to happen when the two pieces were cut apart.  Don't want the thing falling on the floor or something bad like that.
I started in the center and worked to the left side.   Working from the back, I had excellent access.  The die grinder worked fine.  The gap in tape method worked really well.  My cut line was very straight.
Then I cut the right side.  I put duct tape every six inches or so to keep things secure.
From the rear.
And it's done.  Big Cut complete.  Some of my better work.
The aft canopy section.
Putting the forward canopy on the plane, the rear edge fit the roll bar nicely.
The canopy side bottoms are slightly ahead of the cut line.  Other than that, everything looked good.
Looking down at the roll bar.
The front edge still hugs the canopy skin closely.
 
So, the Big Cut is done and everything appears to be in order.  Although it's nice to have it done, I realize there are still many, many hours of work on the canopy before it is done.
 
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