Ok Here is what you need to do -- use 18-8 or 316 stainless but buy flat heads if you have the thickness. counter sink 82 deg. the taper creates its own locking force,,, also use fine threads if you are worried about pulling the threads out -- more surface area than course threads- use the anti seize and you will be fine -- Dont over think this,, it is simple and will work fine..
Here's a suggestion get a pop nut tool it puts a threaded insert into what your bolting to and gives you a bunch of extra threads to work with .just treading the tube you will have very little threads in the tube. I have aluminum inserts and steel inserts don't know if they have stainless ones but the aluminum ones should work good for what you are doing .
Some believe the stainless is inert, but it's not. The seriousness of the corrosion issue varies with the alloys of stainless and aluminum. If the stainless has been passivated that will help a lot. I saw a case where stainless fasteners were installed in aluminum castings in place of the original steel ones. The castings were a at least 30 years old and still in pretty good shape with the original fasteners. With the stainless fasteners the parts were junk in less than a year. In some places you could see patterns of lines where the corrosion happened.
The treaded insert is a sound way to assist in preventing the thread corrosion. Until you have tried, to unweld a stainless bolt from an Aluminum structure, you may not have discovered the "blessed St. Anti-seize".
I guess that would create it's own "Loctite"! Just hope you never have to take the bolts out again... I'd see what the military fastener spec is for attaching accessory rails to assault weapons. I believe that hardware has to be able to survive in any sort of environment.
Yes, stainless bolts can and do corrode in aluminum. I've seen it again and again on motorcycles. Today I always use anit-seise. In the old days we uses (believe it or not) enamel paint. We would dip the bolt in the paint and insert. I've take apart bolt that were out in the weather for years and the paint on the treads was still soft.
a little side note on stainless screws, while working at a factory building gas stoves we ran into a problem of some #8 screws twisting off, about 50/50, by spreading the screws out on the floor and passing a magnet over them i could pickup the work hardened screws and leave the rest behind, the ones left behind would not twist off when used, i found this info on some online engineering site.
Totally Stainless sells grade 8 (or stronger) in 6 point small hex and 12 point. I think they are made by ARP. The price for 1/4-20x1/2 is about $2 each. Here is a link to their catalog download: http://www.totallystainless.com/Catalog.php
Originally Posted by good_ol_boy ... the books are always wrong. ... Yea I think I read that somewhere ...
Thanks for all the input. Have attached a few pictures of the other rigs for my ATV. One is with the Camera Crane attached. The other is for Steadicam attachments. These posts I asked for help will go where the Operator seats are front and back. The posts will hold robotic camera heads and cameras. Appreciate all the help.
Most everybody is tying to over engineer the project. If you use anti-seize you will be fine. The 1/4 x 20 threads are a course thread, aircraft primarily use fine thread hardware. How thick is the aluminum plate, 1/4 thick. 1/8? A rivnut may be required to secured the bolts. I would be more concerned with vibrations rather than corrosion. This is all basic aircraft maintenance knowledge. Good luck Mark
I must admit this all looks like its being over thought to me, I have used ARP stainless for the last 25 years on all my cars and just installed with anti sieze, never had a problem and they always undo as they should.
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