I didn't realise that the spline was that hard to find. I have a Mom and Pop hardware store (Meadowbrook Hardware) close to me. I just go there first out of habit. They had it and the next size larger.
Beginner
Hey....if you have a star crack showing...its not Lexan. It won't do that.
Melody- my experience follows
Um ah, from one airplane builder to another. I've seen numerous instances of star cracking on lexan windscreens installed on experimental aircraft. This is almost always caused by the builder drilling out only to the called rivet size. The correct way is to drill out to the called rivet size then give it a little more clearance. I don't have the info here with my morning coffee, you'll just have to trust me on that. Why oversize holes?- because polycarb has movement when it heats and cools, if held tight it will crack. True Story. I posted pics some time ago on another thread, try the defunct search if you need something to do. Also with google availability anyone should be able to purchase lexan, polycarbonate anywhere on the planet and have it shipped to them. Plastic supply places have it all the time, it's readily available if you know where to shop.
on edit --look at the thread "rock guard rebuild-71 Safari" pics of star cracked lexan.
__________________
The 2 worst things that can happen to an old aviator:
(1) One day you will walk out to your aircraft,
knowing that it will be your last flight.
(2) One day you will walk out to your aircraft,
not knowing it will be your last flight.
Proud Appellation American
Last edited by doorgunner; 09-17-2007 at 08:49 AM.
Reason: found other thread
Thats absolutely correct. After the first drill to size I will go one size over...plus I will use a large bit...or countersink, to bevel both ends on the drill hole. The star crack I was thinking of was from a direct blow...like a windshield type. Bullet holes don't count.
I'm interested in finding a source for the materials for building a rock gaurd....do you have that already? I'm in Va and get over to Norfolk once in a while.....
Quote:
Originally Posted by Beginner
I didn't realise that the spline was that hard to find. I have a Mom and Pop hardware store (Meadowbrook Hardware) close to me. I just go there first out of habit. They had it and the next size larger.
Beginner
Last edited by overlander63; 01-23-2008 at 09:41 AM.
Reason: fixed quote
I gotta ask... how often have you seen frozen chickens flying by when you are airborn?
Happens to me often....on Saturday nights....Maybe the beer and BBQ has something to do with it.
I found a 4x8 sheet of Lexan at a local Mom-n-Pop glass shop for just under $200. I had to cut it myself to fit the old frame, which can be very tedious, but it came out really nice. Take a look: http://www.airforums.com/forums/496827-post466.html
Jim
__________________
What is that line from "Miracle on 34th Street"? Something like "Maybe he's only a little crazy, like those men in Washington."
I'm interested in finding a source for the materials for building a rock gaurd....do you have that already?
Walt. I've seen a couple homebuilt rockguards on Forums in years past but wouldn't be able to put my finger on the location. I don't recall enough details to tell you how they were done. They didn't look that great nor offer the function that OEM rockguards do. An Airstream dealer should be able to tell you what is available. If your local dealers aren't interested, Out-of-Doors Mart gives great service.
Just to clear up a couple of error in this thread. The original transparent rock guards were make from Acrylic sheet. Acrylic is the short generic name for PMPA polymer. Rohman Haas's trrade name fo it was Plexiglas. Dupont's trade name for the same material was Lucite. Cyro Industries and several others also made this polymer under various trade names. In error, many people just call it all Plexi.
Polycarbonate is the generic name for a higher impact polymer that was invented much later. GE named it Lexan. Bayer and Monsanto made the same kind of material under their own tradenames. GE recently sold their plastic business to Sabric so they now own the Lexan tradename. PC as the plastic people call it is a little softer than PMPA but much more impact resistant. PC and PMPA are sensitive to a variety of chemicals and can craze or crack when exposed to them when the material has a stress or an internal stress (like poorly drilled holes) applied.
Just to clear up a couple of error in this thread. The original transparent rock guards were make from Acrylic sheet. Acrylic is the short generic name for PMPA polymer. Rohman Haas's trrade name fo it was Plexiglas. Dupont's trade name for the same material was Lucite. Cyro Industries and several others also made this polymer under various trade names. In error, many people just call it all Plexi.
This is the same issue that gets all cola-flavored sodas called "coke", all snowmobiles called "skidoos", and all aluminum trailers called "airstreams"...
__________________
Terry Change is inevitable, except from a vending machine
AIR#2611
I gotta ask... how often have you seen frozen chickens flying by when you are airborn?
Terry,
I was referring to the testing the Air Force once did on canopys. They were trying to test for breakage should a midair occur with a duck or goose, problem is they were not thawing the chickens they were blasting at the canopies! I thought everyone had heard this story.
Or was that McDonald Douglas.
__________________
The 2 worst things that can happen to an old aviator:
(1) One day you will walk out to your aircraft,
knowing that it will be your last flight.
(2) One day you will walk out to your aircraft,
not knowing it will be your last flight.
Terry,
I was referring to the testing the Air Force once did on canopys. They were trying to test for breakage should a midair occur with a duck or goose, problem is they were not thawing the chickens they were blasting at the canopies! I thought everyone had heard this story.
Or was that McDonald Douglas.
I did hear the story, but the mental picture of frozen chickens flying around was perversely funny.
__________________
Terry Change is inevitable, except from a vending machine
AIR#2611
I did hear the story, but the mental picture of frozen chickens flying around was perversely funny.
The first images that came to mind for me were those of the Mythbusters' "chicken cannon" where they fired frozen chickens at an old Piper's (I think) windshield. Made pretty short work of it, IIRC.
Now that's quality television!
__________________
Cheers, Dave
"Finish." AIR #4188 1994 34' Limited / 2002 Chevy 3500 CC 4x4 D/A Equal-i-zer Hitch / Jordan Ultima 2020
Quick Links
Linear Mode
