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12-31-2007, 12:54 PM

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fancman

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RE: 4-40 Bolt - What's this mean?1

You have a size 4 bolt with 40 threads per inch. 4-40X1/2" Now you have the length. Here is a bolt chart:

http://store.nutsandbolts.com/threads-per-inch.html

http://www.ligo.caltech.edu/docs/T/T030118-01.pdf

Quote:

ORIGINAL: MasterAlex

Okay, in the "there's no such thing as a stupid question" category - he's my last one for the year

The last time I flew my SSE the canopy bolt jettisoned itself from the airframe during a series of aileron rolls. Silly me it was the 3rd or 4th flight of the day on that plane and the bolt must have worked itself loose [:@] - I should've checked it, I know. Fortunately, the canopy stayed on the plane!

Anyway, I have been trying to find a replacement for this little bugger and I am at a loss; well, probably not, but I need some guidance from you guys. The bolt is 4-40 1" nylon. Now here's the aforementioned question:

What does 4-40 mean? 4mm by ?? ... is the second number the number of turns on the thread every inch? What's the secret code here? I have been to several hardware stores and have not seen any hardware with the 4-40 nomenclature. Is this also known under some other branding?

Can someone please unlock the mystery for me??

Thanks!!

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