Months ago, we made some small machine parts from 1" x 1/2" x 2" ground
stock from McMaster. The instructions to my heat-treater were to make them
"as hard as possible" 58-63R. They are a big outfit running 24/7 and do a
lot of 0-1. But, when we got the parts back we tested to 49R. We had taken
out tester there many months ago to make sure we and they got the same
readings. When we called about the low numbers they said our parts were
with a big batch that tested OK. they didn't test our parts specifically.
They said it was probably the steel. We used the parts hoping 49R was good
enough...it wasn't. The parts have a carbide pinch roller in a slotted
pocket and the carbide coined into the roof of the pocket in a few months
and now won't function properly. The bitch of it is that the parts have 12
really, really persnickety, time consuming machining operations with pockets
at angles and tiny slots and holes.

So, I have to make new parts and I still have a couple feet of the same bar
and need the parts right now! I had my "Midnight Machinist" get started
tonight to make at least 2 parts (they work in pairs) that had to be
finished ASAP and I'll heat treat them in-house even if they only hit 49R.

So, did the steel fail or the heat treater? I don't think I've ever had 0-1
fail to harden before, is it common? Tomorrow, I'll cut a whack of the bar,
torch it and test it. If I torch the old part, will it harden like new if I
torch it?

I do have a new mechanism design that will make these parts obsolete if it
works but the prototype is weeks away so I don't want to put a whole lot of
time or money into this but they have to work in two machines until then.

"Buerste" wrote in message
...
Months ago, we made some small machine parts from 1" x 1/2" x 2" ground
stock from McMaster. The instructions to my heat-treater were to make
them "as hard as possible" 58-63R. They are a big outfit running 24/7 and
do a lot of 0-1. But, when we got the parts back we tested to 49R. We
had taken out tester there many months ago to make sure we and they got
the same readings. When we called about the low numbers they said our
parts were with a big batch that tested OK. they didn't test our parts
specifically. They said it was probably the steel. We used the parts
hoping 49R was good enough...it wasn't. The parts have a carbide pinch
roller in a slotted pocket and the carbide coined into the roof of the
pocket in a few months and now won't function properly. The bitch of it
is that the parts have 12 really, really persnickety, time consuming
machining operations with pockets at angles and tiny slots and holes.

So, I have to make new parts and I still have a couple feet of the same
bar and need the parts right now! I had my "Midnight Machinist" get
started tonight to make at least 2 parts (they work in pairs) that had to
be finished ASAP and I'll heat treat them in-house even if they only hit
49R.

So, did the steel fail or the heat treater?

You can't tell from this information. When hardness is critical, send the
heat-treater a couple of coupons cut from the stock you're using before you
send him the finished parts. If you have time, await the hardening results
on the coupons before machining the parts.

O1 is a very reliable steel but, unless the source of your steel is
certified, God knows where it came from or who made it.

I don't think I've ever had 0-1
fail to harden before, is it common?

It's not common in O1.

Tomorrow, I'll cut a whack of the bar, torch it and test it. If I torch
the old part, will it harden like new if I torch it?

Probably not. Soak time will be a variable if the steel starts in a hardened
state. O1 is relatively insensitive to it, but a torch isn't going to be
reliable enough for the test you want to do. And if the part failed its
hardness test in the first place it could have been due to burning or
excessive soaking, which will keep the part from re-hardening properly but
won't tell you a thing about the rest of your steel stock, or about how your
heat treater will perform with the *next* batch.


I do have a new mechanism design that will make these parts obsolete if it
works but the prototype is weeks away so I don't want to put a whole lot
of time or money into this but they have to work in two machines until
then.

If your heat treater is running O1 parts all the time and if it won't cause
unacceptable delay, send the coupons first.

--
Ed Huntress

I need to get my mind out of the gutter. I thought you were running an ad
for Viagra

Karl

"Karl Townsend" wrote in message
anews.com...
I need to get my mind out of the gutter. I thought you were running an ad
for Viagra

Karl



You're starting to get old and your priorities affect your thinking...just
wait a few years and "Tool Steel" will mean you are having a really good
day.

On Dec 7, 7:20*pm, "Buerste" wrote:
Months ago, we made some small machine parts from 1" x 1/2" x 2" ground
stock from McMaster. *The instructions to my heat-treater were to make them
"as hard as possible" 58-63R. *They are a big outfit running 24/7 and do a
lot of 0-1. *But, when we got the parts back we tested to 49R.

So, did the steel fail or the heat treater?

The prescription for O1 hardening is to quickly oil-quench; if your
part is complex (thick and thin parts) it might not quench perfectly
uniformly. Can you ask your heat-treater about air-hardening
steel options?

"Buerste" wrote:

So, did the steel fail or the heat treater?

Were your small pieces next to a much larger piece? Might have changed how quickly it was
quenched.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller