Lead of NAS1580

Lead?

Thread size & pitch?

This is a

Bolt, 100 Flush Head, 95 Ksi Shear Document Number: NAS 1580

I don't have copy of this spec but I'd bet lunch its a stnadard US aerospace fine thread fastener UNF-2 (or maybe class 3)

.1895.-32 (10-32) .250-28 .3125-24 .375-24 .500-20

hope this helps Bob

Thanks Bob! Appreciate your help! I'm a novice at this! Any good reference to read up on screws and bolts?

Machinery's Handbook

I don't have access to new revisons of NAS & MS fastener specs but I have super old (~16 years) paper copies.

Typically a spec covers a particular fastener; the diameters & lengths are tabulated in such a way that the part number is modified with "dash" numbers to callout diameter (thread size) & bolt lengths.

Some fasteners have different main number for sizes & the dash number just specifies length.

Some main numbers I remember

NAS173 10-32 Hex Head Bolt, Close Tolerance MS21250 12pt, High Strength Bolt (obsolete but a really cool bolt) MS21042 Nut, Locking, Deformed Threaded, AMS286, silver plated MS21209 Insert, Helical, Self-Locking

MS21250-04-08

If my memory serves:

that would be a 1/4 diameter bolt; the 04 dash specifying 4 16th's (1/4") the length dash number of 08 (I'm not sure but it might mean 8/8ths grip length, the smooth portion of the shank)

for more complicated bolts one can substitute letters for some of the dashes & get head or shank drilled for safety wire.

If you can scrounge a copy (paper or electronic) of any bolt spec it will go a long way to making sense of all of them. They're all similar pretty much & once you get the hang of it, it's easy.

Here's a PDF link to a copy of the MS21250 spec, should help a lot

cheers Bob

I'm on a roll

Bob

Oops!

That NAS173 s/b AN173

Bob