Anyone have some non-destructive tricks to quickly and accurately (and cheaply) determine if rivets (1/4" diameter) installed in steel sheet metal are aluminum or mild steel?
Using a small diameter mag pickup didn't work because of the proximity of the sheet metal. Any chemicals that will react with either steel or aluminum but not both and give a pretty distinct reaction? (Alodine or cold bluing / parkerizing? ) Also, scratching or lightly sanding/filing the rivets is acceptable.
Just scratch the rivet with a cheap machine screw. If it is easy to scratch, it is aluminum.
isnipped-for-privacy@not-real-mail.com (JJ) on Wed, 09 Feb 2011 04:36:52 GMT typed in rec.crafts.metalworking the following:
scratch it, add water, see if it rusts.
See if drill shavings will be picked up by a magnet.
You've already rejected the two most obvious solutions. If there's a rivet head on steel, it should be trivial to tell if the bulge is aluminum or steel, with a little magnet. If it's aluminum, the magnet may be attracted to the steel, but the aluminum will be in the way and the magnet will just fall away. Well, it will stick to the steel around the edges. but the dome of the rivet head will have tangibly less attraction. If the rivet is steel, then the magnet will stick to it preferentially to the steel around it.
And if you can't tell the difference between a piece of aluminum and a piece of steel, even mild steel, with something as simple as a fingernail file or a pocketknife, then you still have a lot to learn about metal.
Good Luck! Rich
The color alone should be more than sufficient to tell the difference. Get some samples of each, and compare.
The problem with chemicals is properly neutralizing them after testing, especially under the head if it's not a perfectly sealed fit.
An awl might work well, too. Stick it in the edge and it should create a crater in aluminum, do nothing in steel.
-- Education should provide the tools for a widening and deepening of life, for increased appreciation of all one sees or experiences. It should equip a person to live life well, to understand what is happening around him, for to live life well one must live life with awareness. -- Louis L'Amour
A good awl may scratch steel quite easily. I have some, like that.
iRich Grise wrote: ...
That's what RCM is here for - to help each other learn. At one time even you did not know how to tell aluminum from steel.
Bob
a big magnet and some iron filings is all you need to see if the rivet is aluminum. Just look at the way the iron filings form around the rivet when you put the magnet underneath it.
John
put the iron filings in a zip lock bag first!
This last sentence is a great one. It works fine and is very easy replicate, how did you think of it?
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how did you think of
Experience!
Try cleaning iron filings off of steel once a magnet has been there...
Probably from experiencing the PITA of picking the filings off the magnet. :-)
Cheers! Rich
Bag it next time, Bubba. (Plastic bag around the magnet, invert it to remove all filings from magnet. Throw bag and filings away.)
-- Remember, in an emergency, dial 1911.
Nothing like having a demagnetizer. A magnetic tape eraser will work on smaller parts, or a electromagnetic chuck with a demagnetizer will work too.
John
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