An upcoming project will have me making 8 different M1.25 spur gears to
replace missing change gears for a lathe that seem to be unavailable
from the manufacturer. I've got a set of gear cutters on the way from
China and I've been reading up on the machining process so I think I'm
good there. What I need to do is figure out the best steel to use so I
can order a chunk of bar from my steel supplier.

I don't have real heat treating capabilities yet, just your basic
Kasinit case hardening. The change gears in the lathe obviously don't
run 24x7 and don't carry huge loads generally so what steel would be
best and not overly difficult to machine? Is case hardening a good idea?
Presumably case hardening doesn't have as much warping potential as real
heat treating, and of course I don't have the capability of finish
grinding though I could perhaps rig up a fixture to run in the new gears
against each other with some lapping compound if that might help.

Thoughts? Suggestions?

"Pete C." fired this volley in news:51883fa6$0
:

Thoughts? Suggestions?

I doubt if a gear with teeth that small would undergo much load at all.

Atlas made small change gears like that for decades from the Zn/Al/Mg
alloy "Zamac". Properly treated and lubricated, they lasted for decades
in light-duty use. I still have an old 6x18 Atlas on a corner table, and
have had it since 1972. I've worn out the spindle pinion and the two
reversing gears, and that's all... and the lathe got used a couple of
hours (under feed) about three times a week from '72 until 1995.

You could probably make them from any alloy whatsoever (including
merchant-stock mild steel), and with case hardening, they'll last darned-
near forever.

Lloyd

On Mon, 06 May 2013 18:41:15 -0500, "Pete C."
wrote:


An upcoming project will have me making 8 different M1.25 spur gears to
replace missing change gears for a lathe that seem to be unavailable
from the manufacturer. I've got a set of gear cutters on the way from
China and I've been reading up on the machining process so I think I'm
good there. What I need to do is figure out the best steel to use so I
can order a chunk of bar from my steel supplier.

I don't have real heat treating capabilities yet, just your basic
Kasinit case hardening. The change gears in the lathe obviously don't
run 24x7 and don't carry huge loads generally so what steel would be
best and not overly difficult to machine? Is case hardening a good idea?
Presumably case hardening doesn't have as much warping potential as real
heat treating, and of course I don't have the capability of finish
grinding though I could perhaps rig up a fixture to run in the new gears
against each other with some lapping compound if that might help.

Thoughts? Suggestions?

There's more to it than this, but as a starting point, this is what I
was taught years ago by Gleason Works, who were world-class experts.

For quality machinery applications, the best gears are made from a
case-hardening grade and deep-case hardened. That's not Kasenit, but
an expert could do it with a compound like that. What Gleason was
talking about is case-hardening in a carbon-rich atmosphere, in a
furnace, for a long time: hours, usually, to produce a case that's
0.1" thick or more.

The next step down is flame-hardened gears. These are made from
high-carbon steel, or a quick-quenching high carbon alloy. This flame
hardening requires a fixture and a quenching system that surrounds the
gear all at once -- a spray-type or an agitated oil bath.

The next step down is through-hardened alloy gears.

The nest step is anything else. g There are lightly-loaded machinery
gears made of alloy or carbon steels that are half-hardened but still
machinable.

The idea is that you want the contact areas of the teeth to be very
hard for wear resistance, but the roots of the teeth have to tolerate
shocks in most applications.

Good luck! You'll probably get some grade-specific recommendations,
but this will give you an idea of where they fall.

--
Ed Huntress

Ed Huntress wrote:

The next step down is flame-hardened gears. These are made from
high-carbon steel, or a quick-quenching high carbon alloy. This flame
hardening requires a fixture and a quenching system that surrounds the
gear all at once -- a spray-type or an agitated oil bath.

So spin the gear on a mandrel with just the teeth in the O/A flame until
red hot and then quench it in some carbon rich used diesel oil?

"Pete C." wrote in message
...

An upcoming project will have me making 8 different M1.25 spur gears to
replace missing change gears for a lathe that seem to be unavailable
from the manufacturer. I've got a set of gear cutters on the way from
China and I've been reading up on the machining process so I think I'm
good there. What I need to do is figure out the best steel to use so I
can order a chunk of bar from my steel supplier.

I don't have real heat treating capabilities yet, just your basic
Kasinit case hardening. The change gears in the lathe obviously don't
run 24x7 and don't carry huge loads generally so what steel would be
best and not overly difficult to machine? Is case hardening a good idea?
Presumably case hardening doesn't have as much warping potential as real
heat treating, and of course I don't have the capability of finish
grinding though I could perhaps rig up a fixture to run in the new gears
against each other with some lapping compound if that might help.

Thoughts? Suggestions?

I would probably just use 1144 ASTM A311 in as-is condition.

"Pete C." wrote in message
...

Ed Huntress wrote:

The next step down is flame-hardened gears. These are made from
high-carbon steel, or a quick-quenching high carbon alloy. This flame
hardening requires a fixture and a quenching system that surrounds the
gear all at once -- a spray-type or an agitated oil bath.

So spin the gear on a mandrel with just the teeth in the O/A flame until
red hot and then quench it in some carbon rich used diesel oil?

You need to have a carbuerizing flame ( IE lots of soot ) if you want to add
carbon, (or if you do not wish to lose it )

IIRC, you can flash copper plate, as carbon will not pass through a copper
barrier but you probably better double check me on that.

Pete C. wrote:

An upcoming project will have me making 8 different M1.25 spur gears to
replace missing change gears for a lathe that seem to be unavailable

make ****ty plastic gears like in a chinese mini mill and claim it's a
feature, not a cheap shorcut.

On Mon, 06 May 2013 19:39:44 -0500, "Pete C."
wrote:


Ed Huntress wrote:

The next step down is flame-hardened gears. These are made from
high-carbon steel, or a quick-quenching high carbon alloy. This flame
hardening requires a fixture and a quenching system that surrounds the
gear all at once -- a spray-type or an agitated oil bath.

So spin the gear on a mandrel with just the teeth in the O/A flame until
red hot and then quench it in some carbon rich used diesel oil?

Well, I don't think so. The spray fixture I've seen, for gears maybe
16" diameter, had a cricumferential row of nozzles.

And no used oil for that, please. Quenching oil. Otherwise, you'll get
bubbles attached to the steel that leave ocal spots unhardened.

--
Ed Huntress

On May 6, 7:41*pm, "Pete C." wrote:
What I need to do is figure out the best steel to use so I
can order a chunk of bar from my steel supplier.


Thoughts? Suggestions?

You are going to have the tools to make another set if you have to.
So why bother with making gears that will outlast you. I would use
what ever you have on hand. If you have to buy some stock, I would
buy free machining steel.


Dan

I would probably just use 1144 ASTM A311 in as-is condition.

AKA, stressproof. Good stuff Maynard.

But for what you're doing the steel in your scrap bin would last many
years.

Karl

Karl Townsend wrote:

I would probably just use 1144 ASTM A311 in as-is condition.

AKA, stressproof. Good stuff Maynard.

But for what you're doing the steel in your scrap bin would last many
years.

Karl

I don't have a suitable bar in my scrap bin so I have to order from my
supplier anyway. May as well get the good stuff.

"Pete C." wrote in message
...

Karl Townsend wrote:

I would probably just use 1144 ASTM A311 in as-is condition.

AKA, stressproof. Good stuff Maynard.

But for what you're doing the steel in your scrap bin would last many
years.

Karl

I don't have a suitable bar in my scrap bin so I have to order from my
supplier anyway. May as well get the good stuff.

I hauled off about 2 tons of various scrap over the past week or so, mostly
tired of it being in the way..

--if there's any commercial shops in your general area, maybe give em a
call.

On 5/6/2013 7:41 PM, Pete C. wrote:

An upcoming project will have me making 8 different M1.25 spur gears to
replace missing change gears for a lathe that seem to be unavailable
from the manufacturer. I've got a set of gear cutters on the way from
China and I've been reading up on the machining process so I think I'm
good there. What I need to do is figure out the best steel to use so I
can order a chunk of bar from my steel supplier.

I don't have real heat treating capabilities yet, just your basic
Kasinit case hardening. The change gears in the lathe obviously don't
run 24x7 and don't carry huge loads generally so what steel would be
best and not overly difficult to machine? Is case hardening a good idea?
Presumably case hardening doesn't have as much warping potential as real
heat treating, and of course I don't have the capability of finish
grinding though I could perhaps rig up a fixture to run in the new gears
against each other with some lapping compound if that might help.

Thoughts? Suggestions?


I've made gears from O-1 that have run 8 hours a day for 20+ years and
still look like new. I had a bar of 4" dia. at the time so that was
used. No heat-treating, no nothing! O-1 is tough stuff and machines
well enough. What steel do you have in the rack? Use that! Don't over
think it.

Pete C. wrote:

An upcoming project will have me making 8 different M1.25 spur gears to
replace missing change gears for a lathe that seem to be unavailable
from the manufacturer. I've got a set of gear cutters on the way from
China and I've been reading up on the machining process so I think I'm
good there. What I need to do is figure out the best steel to use so I
can order a chunk of bar from my steel supplier.

Something soft enough that it won't destroy
those Chinese gear cutters (:

I don't have real heat treating capabilities yet, just your basic
Kasinit case hardening. The change gears in the lathe obviously don't
run 24x7 and don't carry huge loads generally so what steel would be
best and not overly difficult to machine? Is case hardening a good idea?
Presumably case hardening doesn't have as much warping potential as real
heat treating, and of course I don't have the capability of finish
grinding though I could perhaps rig up a fixture to run in the new gears
against each other with some lapping compound if that might help.

Thoughts? Suggestions?

Tom Gardner wrote:

On 5/6/2013 7:41 PM, Pete C. wrote:

An upcoming project will have me making 8 different M1.25 spur gears to
replace missing change gears for a lathe that seem to be unavailable
from the manufacturer. I've got a set of gear cutters on the way from
China and I've been reading up on the machining process so I think I'm
good there. What I need to do is figure out the best steel to use so I
can order a chunk of bar from my steel supplier.

I don't have real heat treating capabilities yet, just your basic
Kasinit case hardening. The change gears in the lathe obviously don't
run 24x7 and don't carry huge loads generally so what steel would be
best and not overly difficult to machine? Is case hardening a good idea?
Presumably case hardening doesn't have as much warping potential as real
heat treating, and of course I don't have the capability of finish
grinding though I could perhaps rig up a fixture to run in the new gears
against each other with some lapping compound if that might help.

Thoughts? Suggestions?


I've made gears from O-1 that have run 8 hours a day for 20+ years and
still look like new. I had a bar of 4" dia. at the time so that was
used. No heat-treating, no nothing! O-1 is tough stuff and machines
well enough. What steel do you have in the rack? Use that! Don't over
think it.

I have no steel bars large enough to make the gears. The closest I would
have is some 3/8" A36 plate. Easier to just order up what I need along
with some other stuff I'll need for other projects and let them deliver.

Very realistic approach, excellent observation.. although I really don't
appreciate needing to redo previous work, which isn't likely to be needed in
this situation.

--
WB
..........


wrote in message
...

You are going to have the tools to make another set if you have to.
So why bother with making gears that will outlast you. I would use
what ever you have on hand. If you have to buy some stock, I would
buy free machining steel.


Dan