Stainless steel bolts ---

[Christopher Crowe]

I needed a 10-32 hexhead countersunk bolt for a particular application, couldn't locate an aircraft part, so I bought stainless (unspecified beyond that) -- from McMaster.

How much variance is there in stainless steel bolts. That is; if it's "stainless," is the metallurgy a constant... or can there there be mean, bad, low down, mud-slut stainless?

[lancer360]

You can get some control of the strength by specifying a ASTM F879 Grade 316 CW (cold worked). This will get you a tensile strength of 95,000 psi. If you are getting them through McMaster-Carr, you might want to call them to make sure they are to this specification. Otherwise, see if there is a Fastenal near you. They should be able to get these for you.

[Christopher Crowe]

Thanks!

[Brian]

I look at stainless as equivalent to grade 2 SAE. They aren't as strong as other socket headed cap screws. They also gall like crazy, you can cold-weld one to a steel part in no time and be cutting it out. It also machines poorly so avoid having to drill it for safety wire.

Brian

[RobLav]

What is the application? I've found countersunk 10-32 allen head screws, but they had the SAE rather than AN countersink angle. I try not to use them. I now use aircraft countersunk Phillips head screws with those cool washers instead. You can find them at Aircraft Spruce.

[Wren]

Most stainless bolts/screws are 18-8 which is not an especially strong grade. It is fine for holding bodywork on, but not meant for high strength applications.

Consider using phillips instead, there seems to be more quality fasteners available.

Make sure your countersinks match.

[starkejt]

Skip stainless unless you need corrosion resistance. Alloy steel hex socket (82 deg) are available in a fairly high strength. NAS 100 deg screws are probably preferable. They are available with a standard Philips or offset cruciform (aka torq-set) as NAS1102 series. They require a special driver and you will need to c'sink 100 deg, but are 160-180 ksi UTS.

http://coastfab.com/images/pdf/2010/bolts_nas1102.pdf

ETA: look up NAS1203 and NAS1580 if you don't want fully threaded, i.e. if you intend to put a nut on it.

[Christopher Crowe]

Is there a special tool for cruciform heads?

[starkejt]

For offset cruciform, yes.

[starkejt]

This is helpful for any cruciform fastener.