Threading aluminum....

[gstone]

I have to thread aluminum for a few #6 screws to hold fairings on my Rocket. Any tricks for this and is AN better than stainless for corrosion?

Thanks for any help!
Greg

[Ron B.]

Use something like Rapid Tap for cutting fluid and go slow. Make sure you use the correct pilot drill size.

[GAHco]

Try rubbing alcohol to keep the chips clean and cutting smoothly!

[chaskuss]

Originally Posted by gstone

I have to thread aluminum for a few #6 screws to hold fairings on my Rocket. Any tricks for this and is AN better than stainless for corrosion?

Thanks for any help!
Greg

Yes, Cad plated steel hardware [AN] will not cause corrosion of your skins. The plating is a sacrificial material. If you are into boating, it's like the zinc bolted to the outboard motor or the out drive to protect the aluminum from corrosion. Over years or decades, it will get used up. At that point, you will need to replace the fasteners. See

http://www.eaa1000.av.org/technicl/c...n/galvanic.htm

2024-T4 [not sure if that's a misprint] is #24 on the list. Any metal below #24 placed against it, will cause corrosion of the 2024. Any metal higher on the list, will corrode first.

Charlie

[gstone]

As usual!! Thanks so much!

[Mudfly]

I don't have any airplane building experience ...yet, but I've used helicoils for aluminum motorcycle parts with very good success.

http://www.helicoil.com.sg/HeliCoil-...-Inserts.shtml

[tim2542]

Thread inserts are a good way to go. Commonly used AN fasteners are SAE threads, 10/32 for example, and are generally not good for use on aluminum or even cast iron. USS threaded AN fasteners are available but hard to find. Inserts installed from the git go may eliminate future problems.
Tim

[Bob Kuykendall]

One important thing to keep in mind is that 6-32 is the very weakest tap size. That is because the minor diameter at the thread root is a greater percentage of outside diameter than for any other common combination of shank diameter and thread pitch. Use a good quality tap, and work slowly and carefully so you don't break the tap off inside a longeron and have to go in and dig it out.

Thanks, Bob K.

[Stoo]

Use a high speed steel spiral point tap, not a carbon steel hand tap from the hardware store. eg.[url="http://http://www.mcmaster.com/#spiral-point-taps/=lb9pny"]
Spiral point taps work well as hand taps and the angled cutting edge at the point pushes the chips ahead of the tap and out the hole. This greatly reduces the chance of binding and breakage due to chips building up in the flutes. Definitely use a lubricant------- Boelube, kerosene or oil all work well.

Stewart Willoughby
6, finishing.

[gstone]

Thanks Stoo, I'll order a couple in the morning! Bob, I've had trouble with the very thing you are talking about but really trying to minumize the hole size of the hole, might look at going up to a #8???

Thanks again all!!