AIRCRAFT QUALITY BOLTS

Well Erik, I started this thread because I didn't know what was meant by 'Aircraft Quality', but now I think I have come to a conclusion at least to my satisfaction but not to all others. I shall not wish to be argumentative nor just copy and paste statements - they are only statements by others. This is just my opinion, okay....Aircraft Spruce & Specially Co. for example, sells 'Aircraft Quality' only hardware for ones aircraft and most other aircraft parts suppliers do as well, that I saw. I don't think it, "... always equates to some snake oil marketer peddling off crap." Now I believes that when they say 'Aircraft Quality' they mean that they sell only AN (Air Force-Navy), MS (Military Standard) and NAS (?),,I forget...and not something one may buy at a regular hardware store. It is not their fault that we don't know what is the 'standard' in the industry, this be for aircraft parts sales....'Aircraft Quality'. Another thing I 'read' 'stated, is that the EAA type home built aircraft builder may use any old bolt, yes an el cheapo made in China bolt and the FAA inspector will sign off the safety inspection as okay and let you fly it...and take other passengers, sounds strange huh? I would like to verify this. I have dealt with those people in Oklahoma City and I don't think they are up to par. I have seen this 'Aircraft Quality' thing kicked around and now I see it very clearly.

Bob Lowe

------------- Right up there with surgical stainless

Probably does.... and ignores that forgings are usually stronger then something chopped out of bar stock :-)

Actually T-6 is a level of hardening and says nothing about the material itself.

for example:

2024 - T6 - minimum tensile strength 61,900 psi 6061 - T6 - 42,000 psi 7075 - T6 - 78,000 psi

Some materials age harden. In the case of aluminum you solution heat treat it - heat it up, let it heat soak for a period and then cool it very quickly. Subsequent to this the aluminum will continue to harden for some period, quite a long period in some cases. By holding it at an elevated temperature the ageing process takes place much quicker.

A substantial amount of the high performance sailboat masts and spars are 6061, usually marked "T6" :-) I've no idea why as 5052 and 6061 are roughly the same strength so I assume it has something to do with availability or cost.

Yep. If the strength of something I make really matters I proof test it. Small hardware store nuts and bolts are fairly easy to break with a 1/2" torque wrench and 6 point sockets. Some stainless hardware I've bought has been really soft, and I've abandoned 1/4" lag screws for

5/16" because they break too often when unscrewed from predrilled holes in oak. jsw

Which means they can NOT be T6. 1XXX, 3XXX and 5XXX are not heat treatable. 5XXX is a Magnesium alloy and is weldable. 1XXX are "pure" aluminum, 3XXX are Manganese alloys. The 6XXX are heat treatable, weladable magnesium silicone alloys - the silicone allows the heat treating.(forms magnesium silicide wich is "disolved" into the metal by solution heat treating.

But "billet" is not a "cast" block. Billet is technically a "forged" block - with the close grain structure associated with forged metal.

I hope you're waxing any hardware going into hardwood. It extends its lifetime a minimum of 100%. ;)

You're reading something I didn't say, I only said that 5xxx alloys are not heat-treatable. See my other post re spar extrusions and 6xxx aluminums..

My guess is strength after welding and extrudability. 6061 will naturally reharden after welding, though not to its pre-welded T6 condition. 5052 will remain more or less annealed near any welds.

Extrudability:

Ain't that what I said?

replying to John B. , Bob Lowe wrote:

Again, just my opinion. When I first read that some one said that T6 was not a proper 'grade' for aluminum, I thought,wait a minute...I have heard many times things like, "Use T6" or "Get me some T6" or "T6 will do just fine." We know that that the full Identification number of a metal alloy is the chemical make-up of the alloy and of course 6061 is a common one. If someone says 'use T6', and knows what he is talking about, he is saying that I don't really care just what the alloy type or alloy number it is, just that the 'T6' is tough enough and suitable for the job and some types are not adaptable for T6 hardening so he is covered. If 6061-T6 is specified, they are just being more specific, which in my opinion is okay, but not required in some circumstances. As for the 5052 and 6061 alloys having about the same strengths, I would think that there are many aluminum alloys that have similar strengths but have other different properties, such as corrosive resistance, and as you say, cost and availability could be major factors. One time in LA I bought a boat and after a year or so I noticed that some of the aluminum hardware had turned to a white dust and I bought some 'boat' grade stainless as replacements. Maybe the 'boat grade' could have been more specific of course. And as for the Aluminum Billets can not be of cast as someone said...I don't believe this....As far as I am concerned, Cast Aluminum Billets have been made since Aluminum has been used - All billets are not created equal. A lot of people get too hung-up on semantics and specifics....That may or 'may not' be correct. Again, just the way I see things. After a little crash-course on 'Aircraft Quality', I am okay, not great, but okay. Thanks.

Bob Lowe

I sprayed LPS-3, which dries to a waxy film, into the boxes of lag screws, and I predrill oak and pressure-treated SYP for the shank and threads, somewhat undersized since the fasteners need to withstand an estimated half ton of snow and ice on the roof. . AFAICT the hard wood scours off some of the zinc, so wax doesn't really have a chance.

I stopped waxing furniture screws because it interferes with staining. I spent this morning sanding off a misguided amateur puttying and staining job in the club's bathroom. On the way home I raided HD's rack of unpretty PT 4x4's at 70% off. The firewood it will support doesn't care what it looks like.

jsw

Or he's operating in a context where T6 may assume a specific family of alloys. For example, you're not likely to find 7075 or 2024 in a marine fabricator's shop where T6 plate would almost cetainly mean

6061.

There's a big difference in the mechanical properties of alloys in the T6 condition, and T6 is not enough to specify the strength of a piece of stock. The yield and tensile of 7075-T6 is almost twice that of

6061-T6.

Are you using tapered drillbits? If you're scouring the galv off it on the way in, the hardware won't last in PT, anyway. LPS-3 should be good.

Ewwwwwwwwwwwww! Wood shouldn't be stained. Use a clearcoat, fer Crom's sake! But if you must stain, finish the wood first, then drill and assemble. Pieces of carpet on your drillpress are friendly to prefinished furniture components.

Funny, that. ;)

Perhaps. There is usually a certain amount of welding on masts and spars, if only to attach the end fittings, and I suspect that it is unlikely that every shop has a forty or fifty foot heat treating oven ;-)

Well, your boat aluminum turning to white powder, that is quite common as while aluminum does form a thin layer of aluminum oxide which protects it, to some extent, from corrosion it doesn't seem to work in conjunction with the stainless screws and such that is used to hold the aluminum to the boat :-)

As for "boat grade" stainless, I will say that I've never seen that designation. You go to a chandlery and a nice shiny fitting is laying there, it probably doesn't have a mark on it. It might be shiny silver or shiny gold colored, but I've never seen one with a stamp, "Made from boat stainless". Heck, they aren't even stamped "hinge" although that is obviously what they are :-)

One time, I was in N. Louisiana, a bloke came in the shop to have something made, and told me that he wanted it made from "good iron", when I asked him "what kind of good iron do you mean", he replied "Like a Ford rear axle". Another chap (from the fire department) came in, wanted a "fat thread" bolt. When I said, "fat thread?" he explained that some bolts have fat threads and some have skinny threads...

What people ask for is not always an accurate description... :-)