Is there a good rule-of-thumb to judge how oversized a piece should be when hot so it's the right size cold? Say you want 1/2 X 3/8 finished? How much larger should it be hot?

Steel expands/contracts at a rate of .0000065 inches per inch per degree Fahrenheit. So a 1.0 inch long piece of steel raised 1000 degrees F would measure 1.0065.

Sorry if this is more technical than you need. Hopefully someone has a good rule of thumb.

Dan

1/4 inch per foot shrinkage from liquid---roughly

Make that 3/16 from a yellow heat.

If one calculate on 1832 degrees F the shrink/expantion factor is 1.2 %
but on average forging temp which is 1500 F IT IS 1 %
And those two numbers are easy to remember
Hofi

Thanks all. It's a tiny amount for 1/2" but it means I'm going to have to upset the post vise wedge I just made. Drat!

Here I thought you meant it was cold out .

I seem to recall that a formula for shrinking wagon tires was 1/8 per foot.

before or after swimming?

I wondered if anyone was going to respond to the rather obvious pun! Took five posts before we got one. Incredible discipline :-)

I was looking around for the expansion coeffecient of steel.. and found any where from .000006 to .000011 per degree F

Assuming you could find it at all. There were a lot of tests,

BTW how do you use things like the modulus of elasticity or the formaula about bending/ deformation/malleability ( Yeah I know I am kinda a mah/ physics head, besides its fun to spout big numbers during demos... ohhhs and ahhs like iron and steel are that hard)