RE: [CAD_CAM_EDM_DRO] Re: New guy with questions

On the shop made cutting tool subject, I would definitely recommend the air hardening tool steel. It cuts nicely and has the least distortion of the hardenable tool steels. Another benefit is that there is very little scale to clean up after hardening, unlike oil or water quenched tool steels. I just recently made some guide blocks for my vertical bandsaw and was able to install them immediately after air cooling. That's convenient!

Thanks,

Ward M.

wardmerk@... <mailto:wardmerk@...>



#)-----Original Message-----
#)From: JanRwl@... [mailto:JanRwl@...]
#)Sent: Friday, October 12, 2001 8:36 AM
#)To: CAD_CAM_EDM_DRO@yahoogroups.com
#)Subject: Re: [CAD_CAM_EDM_DRO] Re: New guy with questions
#)
#)
#)In a message dated 12-Oct-01 10:46:02 Central Daylight Time,
#)johnhe@... writes:
#)
#)
#)> How does oil hardening tool steel work chemically? I know you
#)can heat and
#)> dunk in oils instead of water for less harsh tempering.
#)>
#)>
#)
#)John: It's not "chemically", but "physically". The alloy-molecules
#)"skruntch up" upon rapid-cooling, making alloy-bonds (whatever
#)you call 'em—I
#)am not an eddikatid metul urge ist!) happen. Since the "oil
#)hard" steel is
#)more expensive (to buy in rods and bars), it must have more magic
#)in it than
#)"water hard". There is also "air-hard", but I don't know how it
#)compares.
#)
#)I THINK the oil-hard is more or less "ready to use" after
#)quenching in oil,
#)whereas the water-hard is so brittle it must be carefully "tempered"
#)(re-heated a special controlled amount that takes years of skill
#)at "reading"
#)color (redness) of metal, knowing when to stop re-heating, and HOW to
#)cool-down, properly. But I am NOT sure. When I need a
#)"one-time" tool of
#)some kind, I often don't even pay much attention to which is
#)which, and just
#)plunge the orange-hot tool in whatever's handy (my oil-bucket for this
#)doesn't evaporate as does water, so, often it's "just oil". This
#)works, at
#)least for one-time, non-professional tools, so I retain ignorance!
#)
#)Some metallurgist/tool-maker should answer this question for us all!
#)Well?????
#)
#)Jan Rowland
#)