heat treating steel

[Dave Nereson]

----- Original Message ----- 
From: "Carl Meyer" <cmpiano@comcast.net>
To: <pianotech@ptg.org>
Sent: Wednesday, January 05, 2005 6:08 PM
Subject: heat treating steel


> 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


    I had a blacksmith friend who helped me make a custom backcheck bender 
that actually fit around the bridle wire.  We used "tool steel," whatever 
that is, heated it up to red hot, I think, to anneal it (make it soft) in 
order to file, grind and shape the tool to how I wanted it.  Then to temper 
it, we re-heated it slowly, watching the subtle (VERY subtle) changes in the 
color of the metal and when it got to straw yellow, we quenched it, in water 
I think.  I forget the sequence of colors and it would take me a while to 
look it up.
    There are many many kinds of steel alloys and they all have slightly 
different temperatures and procedures for tempering them.  I, too, wish 
there was a small chart that condensed some of this knowledge for amateurs.
    The backcheck bender worked well for almost 20 years, then it finally 
cracked and broke one day.  I've since tried to make or alter other tools, 
with varying degrees of success (rarely) and failure (mostly).  Trying to 
temper small narrow tools has been a problem -- like the tip of tapered 
capstan regulating tools, stringing hooks, small screwdrivers, etc.  It 
seems I can never find a stringing hook where the hook doesn't eventually 
un-bend or break off, and almost all the screwdrivers I've used on brass 
rail actions end up with their blades twisted.
    I did see a small book on metal working, tool making, tempering, etc. in 
a model railroad store, but it was fairly expensive (intended for those who 
have machine shops and build their own live steam locomotives).
    --David Nereson, RPT