Material for hinge pins in aluminum

"Nok" fired this volley in news:4e8ba5c2$0$1996$ snipped-for-privacy@cv.net:

There are a few: First, aluminum on aluminum tends to gall. If nothing else, this will make the hinge "creaky" and hard to work.

Second, unless you specify exactly the same alloy from the same source for the hinge tubes and the pins, you'll get dissimilar metals corrosion in the joints. That tends not to happen with stainless-on-aluminum (although they are dissimilar metals, also).

Third, mill-finish aluminum tends to easily corrode upon exposure to the elements. SS hinge pins will at least keep the running surfaces "polished" instead of pitting (together) and becoming hard to move.

In any case, keep them protected from the elements, well-lubricated, and moved often.

LLoyd

It sounds as if the hinge pins will not have much stress. How about using some plastic pipe for hinge pins? Maybe CVPC. It will not rust and will not encourage the aluminum to rust. It is very cheap.

=20 Dan

I would be another who agrees that you will get better end results using a different metal for the pins.

Keep in mind that you don't need to use solid stainless rod if the strength is not necessary. Just some stainless 1/16" thick wall tube will work also, since the stainless isn't going to wear through mechanically.

If you cannot (or don't) want to precisely size both the hole and the pin OD, then just get some 1" OD stainless tubing of ~1/16"-1/8th thickness and slice it lengthwise to make a giant 'roll pin' (smooth off all the burrs of course). With a lengthwise cut, the tube will go into the hole even if the hole is slightly undersize or uneven.

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I'm building a project that has a bunch of cro-mo tube pivots for aluminum parts, right now. I tried using aluminum tube first, but it would quickly get "sticky" despite being oiled & coated with powdered teflon during assembly. The cro-mo pivots (lubed the same way) work perfectly.

Copper or stainless 1" OD tubing would be stronger than plastic. A foot of tubing doesn't cost very much.

-jim

I assume that the "well" is fresh water but aluminum and stainless mixed in a salt water/air environment causes considerable corrosion of the aluminum.

What do you calculate the max load to be?

The definition of an engineer that I like is someone who builds things that any damn fool can build, but does it for less money.

=20 Dan

Yup. Or brass?

You're right. I misread it as ID.

What Lloyd said. Here is a useful table of some typical coefficients of friction:

-- Best -- Terry

It sounds as if the hinge pins will not have much stress. How about using some plastic pipe for hinge pins? Maybe CVPC. It will not rust and will not encourage the aluminum to rust. It is very cheap.

Dan

You are welcome. Sounds like you came up with a better version of what I was thinking of.

Dan