[TheForge] Rivets & heat

[Steve Bloom]

Greetings guys--

There has been some discussion about whether holes enlarge or shrink 
when heated. And that remined me of the parable about the number of 
teeth in a horse's mouth, i.e., arguing from authority vs empirical 
determination.

If you need a definitive answer from the world of experimental 
"science", check out:

www.ironflower.com/tips/rivet & heat experiment.jpg

In a nutshell -

(1) drill a 1/4" hole in a piece of scrap 3/16" steel plate

(2) find a 1/4" rivet and grind a taper on the end

(3) verify that the rivet easily slides into the hole (no hammer or even 
a push needed)

(4) heat the plate around the hole to a mild orange (~1500 F)

(5) find that the rivet no longer enters the hole

(6) pick the rivet off the floor, water quench and repeat steps 4 & 5 
(an 'N' of 2 for the statistically inclined <grin>)

(7) quench the plate & rivet back to air temp and

(8) find the rivet will enter the hole but needing a whack with a hammer.

so - the hole shrinks.

Steve