heat treating steel

[Carl Meyer]

Almost any alloy of steel can be checked on the net for the specs for 
annealing, hardening and tempering.

My question is:  Is there an easy way to guess the approx temp of steel? 
Cherry red, or what?

If it says quench with oil, what will happen if you use water?

If it says quench with water, what will happen if you use oil?

If you didn't heat it quite so hot and quenched it, would it be less hard 
and not so brittle?

I wish I knew more about this, but I'm too old to go take a masters degree 
on it.

The instacoilers sold by Schaff have cracked because they were not tempered. 
Two that a friend ordered were cracked on arrival.  The one I ordered 
several years ago finally bit the dust and cracked.  I'm trying to make a 
few and I've got one done.  (Some redesign was done).
The big problem is to make a tapered square hole in the end of a half inch 
rod.

Anybody know about amateur heat treating?  Thanks.

Carl Meyer
PTG assoc