Thorp Air Command - T18.net

Excellent stuff! Wish I had this info when I did mine 25 years ago. I have a 0.125" windshield which is starting to craze around a couple of the forward fasteners so I need to replace. I will go with a 0.1875" replacement. Been thinking of how to build the aft trim strip(fairing) into the plexiglas. Was thinking of routing 1/16" deep and laying in a fiberglass trim strip so finished trim strip would be flush with the original thickness and extend aft to allow canopy to fit under when closed. No draggy lip! Any one done anything like that?

Sounds like you may be charting new ground with "routing" the plexiglass ! Might prove to be a very expensive experiment with the router (or the tool of your choice). I am not an engineer, but the routing may lead to areas of stress in the glass ? Also the fact you are reducing the thickness of the glass in that area Especially since it attaches to the roll bar there.

RB

I agree with Rich;
When I did my canopy, I tried various tools, like a RotoZip and bandsaw, but the only thing that worked well for me was the Norton Cutoff disc in my die grinder.
Tooling the plexiglass generated too much heat. Then I had melted goobers of plexi rewelding the cut behind the tool.
Also, the Rotozip tool (Dremel tool) had a tendency to take off in some other direction than the one I wanted...potentially hazardous $$$.

I used a 90 degree die grinder with a 1/16" cutoff disc at a speed just fast enough to cut and not so fast as to melt. The 90 degree die grinder I found gave me great control of the cutting. Most of the time it took several passes to make the final cut. All my attach holes were drill initally with a #40 drill (slow speed with a back up block behind the glass), followed by a UniBit drill. The Unitbit drill made a smooth hole and deburred the edges. A 7.5 volt drill was used at about 500 RPM. No cracks !

RB

What Tony is suggesting in not uncommon in production aircraft. In fact they have a tool for such a purpose. I recently performed such an operation on a new windshield for Wendell's Derringer. I used a Drexel tool and a steady hand.

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD