"Tim Wescott" wrote in message
...
I kinda asked this question once before, and got a bunch of answers that
all seemed off the point. So I'm going to try again, and (hopefully)
make my question specific enough this time.

Everybody tells me "use 12L14, it's really easy to machine". I'm willing
to accept that -- I'm using steel that I get surplus, and there's a wide
range of machinabilities that I'm experiencing; I can certainly see how
using the _right_ steel might make a significant difference. But:

If I take some annealed or normalized 1065 steel (or other 10"something
big" steel), get it to the shape I want, and properly heat treat it, it's
going to be a _lot_ harder than when I started. So assuming that I can
machine it in the first place, then get it to hold its shape (or correct
its shape after the fact) and not crack in the heat treat process, I'm
way ahead.

On the other hand, if I take 12L14, get it to the shape I want, and do
the _very best heat treat in the world_, then -- because of the low
carbon content -- it's not going to be much harder. Right?

What about 1144 or 41L40? Do you get much by heat treating these? How
easy are they to machine compared to 12L14? Why isn't there a 12L50?

I've heard tell that 1144 isn't as strong as other steels of similar
carbon content -- true? What about the mechanical properties of 41L40
after heat treat?

I'm basically looking for a steel that'll be suitable for model airplane
crank shafts. The advice that I get from the hobby builders of model
airplane engines is "use 12L14 and don't crash". I'm not going to
discount this -- but it'd be nice to be able to do something on par with
what I buy at the store. So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

--
www.wescottdesign.com


These are really good questions, and I wish I had a specific answer, but I
haven't machined some of those grades and I'm a little confused about the
properties you want.

If "everybody" is getting away with 12L14, at least in normal flight, they
must not need a lot of strength or hardness. They'll get decent toughness
with that grade, at the expense of a low yield point. In other words, it may
not break in a crash, but it will bend, right?

It sounds like you want more strength and toughness. If so, 4140 is a good
choice. Unlike 12L14, adding the "L" in 41L40 doesn't result in a radically
easier-to-machine steel. It gives about 25% better machineability than 4140,
which is mostly of interest in production screw-machine operations.

4340 is better for toughness and strength. These 4000-series alloys get more
hardenability than the 40 points of carbon would suggest, because the
chromium content aids hardening. And those two are tough steels, reasonable
to machine in the normalized condition (which is a way they're commonly
sold), and slow-quenching for safe hardening. 4340 is basically
oil-hardening -- almost air-hardening in small thicknesses.

If it were me, I'd go for 4340. If 12L14 is hard and strong enough in
flight, then 4340 normalized (around 90 ksi yield, IIRC) is a lot stronger
than you need for normal flight, and it's very tough. I'd think it would be
a good choice to tolerate modest crashes. If you leave it normalized, you
wouldn't even have to heat-treat. If you have a fairly rigid lathe, it's a
little slow but not difficult to machine.

This is a semi-educated guess, but I think the ultimate material for
small-engine cranks might be 8620. It's a low-carbon alloy steel that's
really tough. It's made to be case-hardened. If you aren't going to
case-harden, then I'd revert to 4340.

If you can get a piece of 4340 normalized to try, and if you find that you
can machine it Ok, then you might be set. It's a common grade.

Another thing I know little about is the surface finish you can get,
machining small pieces of these various alloys. 12L14 can produce a nice
finish even for hackers. With 4340, it could be more difficult, especially
if you use the annealed grade. I'd consider finishing the crank and bearing
journal(s) by lapping, anyway.

Good luck.

--
Ed Huntress

I kinda asked this question once before, and got a bunch of answers that
all seemed off the point. So I'm going to try again, and (hopefully)
make my question specific enough this time.

Everybody tells me "use 12L14, it's really easy to machine". I'm willing
to accept that -- I'm using steel that I get surplus, and there's a wide
range of machinabilities that I'm experiencing; I can certainly see how
using the _right_ steel might make a significant difference. But:

If I take some annealed or normalized 1065 steel (or other 10"something
big" steel), get it to the shape I want, and properly heat treat it, it's
going to be a _lot_ harder than when I started. So assuming that I can
machine it in the first place, then get it to hold its shape (or correct
its shape after the fact) and not crack in the heat treat process, I'm
way ahead.

On the other hand, if I take 12L14, get it to the shape I want, and do
the _very best heat treat in the world_, then -- because of the low
carbon content -- it's not going to be much harder. Right?

What about 1144 or 41L40? Do you get much by heat treating these? How
easy are they to machine compared to 12L14? Why isn't there a 12L50?

I've heard tell that 1144 isn't as strong as other steels of similar
carbon content -- true? What about the mechanical properties of 41L40
after heat treat?

I'm basically looking for a steel that'll be suitable for model airplane
crank shafts. The advice that I get from the hobby builders of model
airplane engines is "use 12L14 and don't crash". I'm not going to
discount this -- but it'd be nice to be able to do something on par with
what I buy at the store. So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

--
www.wescottdesign.com

"Tim Wescott" wrote in message
...
...So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

Have you ever turned a grade 8 bolt? I think they machine pretty well with
HSS.

jsw

On Mon, 29 Aug 2011 16:20:09 -0500, Tim Wescott
wrote:

I kinda asked this question once before, and got a bunch of answers that
all seemed off the point. So I'm going to try again, and (hopefully)
make my question specific enough this time.

Everybody tells me "use 12L14, it's really easy to machine". I'm willing
to accept that -- I'm using steel that I get surplus, and there's a wide
range of machinabilities that I'm experiencing; I can certainly see how
using the _right_ steel might make a significant difference. But:

If I take some annealed or normalized 1065 steel (or other 10"something
big" steel), get it to the shape I want, and properly heat treat it, it's
going to be a _lot_ harder than when I started. So assuming that I can
machine it in the first place, then get it to hold its shape (or correct
its shape after the fact) and not crack in the heat treat process, I'm
way ahead.

On the other hand, if I take 12L14, get it to the shape I want, and do
the _very best heat treat in the world_, then -- because of the low
carbon content -- it's not going to be much harder. Right?

What about 1144 or 41L40? Do you get much by heat treating these? How
easy are they to machine compared to 12L14? Why isn't there a 12L50?

I've heard tell that 1144 isn't as strong as other steels of similar
carbon content -- true? What about the mechanical properties of 41L40
after heat treat?

I'm basically looking for a steel that'll be suitable for model airplane
crank shafts. The advice that I get from the hobby builders of model
airplane engines is "use 12L14 and don't crash". I'm not going to
discount this -- but it'd be nice to be able to do something on par with
what I buy at the store. So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

Tim, I can't remember what you got for machines. I use plain old
structural cold rolled for most stuff. Its cheap and i got a lot of
it. Machines easily on my equipment.

If i need any perfomrance at all, I move up to 4140 (I assume that's
what you mean by 41L40) It does machine a bit harder but not bad. On
my equipment again.

IMHO 12L14 is an expensive low performance material. I'd only use it
if my machines were marginal as it machines like butter.

karl

On Mon, 29 Aug 2011 16:20:09 -0500, Tim Wescott
wrote:
snip
On the other hand, if I take 12L14, get it to the shape I want, and do
the _very best heat treat in the world_, then -- because of the low
carbon content -- it's not going to be much harder. Right?
snip

It is possible to get 12L14 glass/file hard by case
hardening. You can do this at home with a propane torch.
You may get better results/less distortion from a commercial
heat treater if they can/will piggyback your parts with a
commercial load.

about
http://en.wikipedia.org/wiki/Case_hardening

buy supplies from
http://www.dixiegunworks.com/product...oducts_id=6465
http://www.midwayusa.com/viewProduct...tNumber=119479
there are other brands available


--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"

On Aug 29, 5:20*pm, Tim Wescott wrote:


I'm basically looking for a steel that'll be suitable for model airplane
crank shafts. *The advice that I get from the hobby builders of model
airplane engines is "use 12L14 and don't crash". *I'm not going to
discount this -- but it'd be nice to be able to do something on par with
what I buy at the store. *So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

--www.wescottdesign.com

Take a look at Stressproof. It machines fairly well and has pretty
good mechanical properties without requiring heat treatment. It is a
premium 1144.

http://www.niagaralasalle.com/product-stressproof.html

Dan

On 2011-08-29, Tim Wescott wrote:
I kinda asked this question once before, and got a bunch of answers that
all seemed off the point. So I'm going to try again, and (hopefully)
make my question specific enough this time.

Everybody tells me "use 12L14, it's really easy to machine". I'm willing
to accept that -- I'm using steel that I get surplus, and there's a wide
range of machinabilities that I'm experiencing; I can certainly see how
using the _right_ steel might make a significant difference. But:

If I take some annealed or normalized 1065 steel (or other 10"something
big" steel), get it to the shape I want, and properly heat treat it, it's
going to be a _lot_ harder than when I started. So assuming that I can
machine it in the first place, then get it to hold its shape (or correct
its shape after the fact) and not crack in the heat treat process, I'm
way ahead.

On the other hand, if I take 12L14, get it to the shape I want, and do
the _very best heat treat in the world_, then -- because of the low
carbon content -- it's not going to be much harder. Right?

Right -- as far as you went. Do you want a surface hardness
(e.g. to serve as a bearing) or as a through hardness? Note that the
through hardness is going to make it more likely to break under stress.

And you can get the surface hardness with a case hardening
compound, without the stresses which through hardening can produce.

But the leaded steels don't weld well.

41L42 has a machinability rated at 70% of 1212 (135 SFM)
12L14 has a machinability rated at 197% of 1212 (325 SFM)
1214 is also called "Leaded Grade A"
Leaded Grade B 236% of 1212 (390 SFM)
Leaded Grades AX, AY, AZ 303% of 1212 (500 SFM)

This is all from the Joregensen Steel book No. 71.

What about 1144 or 41L40? Do you get much by heat treating these? How
easy are they to machine compared to 12L14? Why isn't there a 12L50?

Probably because the leading and sulfur which aid machinability
fight the carbon in the supposed 12L50.

I've heard tell that 1144 isn't as strong as other steels of similar
carbon content -- true?

Look it up on the web. There are sites which a Google search
will discover.

What about the mechanical properties of 41L40
after heat treat?

After what cycle of heat treat? You heat it to between 1525 F
and 1625 F, and then quench in oil. This gives the maximum hardness
(and brittle, too). Then you heat it so somewhere between 400 F and
1300 F depending on how much of that hardness you want to get rid of.

And no, the pages which I was looking at don't tell me how hard
it will be after quenching, so I would have to do a Google search to
look that up too -- *that* is your job, not mine.

I'm basically looking for a steel that'll be suitable for model airplane
crank shafts. The advice that I get from the hobby builders of model
airplane engines is "use 12L14 and don't crash". I'm not going to
discount this -- but it'd be nice to be able to do something on par with
what I buy at the store. So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

I don't think that you will find both "easy to machine" and
Grade 5 to Grade 8 bolt hardness in the same metal.

Since this is for a model, so a life is not hanging in the
balance, I would go for the 12L14 to make it easier to make the
crankshaft, perhaps use case hardening for bearing surfaces (and grind
to a finish) and try to follow the "and don't crash" advice. It is
probably easier to make four of the 12L14 or better alloy crankshafts at
one time, than to do the same machining on a 14L40 for one. (Also, the
case hardening should produce less distortion during the heat treating,
so you won't have to leave as much extra metal for finish grinding.)

I know that I try to keep 12L14 on hand and use it for any
project which does not need the extra strength and hardenability of the
other alloys. It is a true pleasure to machine and produces a very nice
finish. Some of these days, I need to get some of the "Leaded Grades
AX, AY, or AZ" steels and try them.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 30 Aug 2011 01:55:38 GMT, "DoN. Nichols"
wrote:

On 2011-08-29, Tim Wescott wrote:


I'm basically looking for a steel that'll be suitable for model airplane
crank shafts. The advice that I get from the hobby builders of model
airplane engines is "use 12L14 and don't crash". I'm not going to
discount this -- but it'd be nice to be able to do something on par with
what I buy at the store. So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

I don't think that you will find both "easy to machine" and
Grade 5 to Grade 8 bolt hardness in the same metal.


"Stressproof" (a modified 1144) has a yield around 100ksi, about
halfway between grade 5 and grade 8 screws. It isn't as easy to
machine as 12L14, but it's not bad considering its strength. This
table rates it about the same as 1018, which seems about right.
http://www.carbidedepot.com/formulas-machinability.htm

McMaster carries generic Stressproof on p. 3633.

--
Ned Simmons

On Mon, 29 Aug 2011 17:57:03 -0500, Karl Townsend wrote:

On Mon, 29 Aug 2011 16:20:09 -0500, Tim Wescott
wrote:

I kinda asked this question once before, and got a bunch of answers that
all seemed off the point. So I'm going to try again, and (hopefully)
make my question specific enough this time.

Everybody tells me "use 12L14, it's really easy to machine". I'm
willing to accept that -- I'm using steel that I get surplus, and

snip

what I buy at the store. So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

Tim, I can't remember what you got for machines. I use plain old
structural cold rolled for most stuff. Its cheap and i got a lot of it.
Machines easily on my equipment.

If i need any perfomrance at all, I move up to 4140 (I assume that's
what you mean by 41L40) It does machine a bit harder but not bad. On my
equipment again.

IMHO 12L14 is an expensive low performance material. I'd only use it if
my machines were marginal as it machines like butter.

41L40 is in the McMaster catalog as an easier-to-machine version of 4140
-- I was wondering if (a) it's really easier to machine, and (b) if the
lead interferes with the strength.

I've got a Smithy, and I rarely have trouble machining the "Mystery
metal" that I get for cheap at the local surplus place. Sometimes I have
to take really light cuts, and getting a really dynamite finish is still
a bit of a mystery for me, but I never have _problems_.

--
www.wescottdesign.com

On Mon, 29 Aug 2011 16:20:09 -0500, Tim Wescott
wrote:

I kinda asked this question once before, and got a bunch of answers that
all seemed off the point. So I'm going to try again, and (hopefully)
make my question specific enough this time.

Everybody tells me "use 12L14, it's really easy to machine". I'm willing
to accept that -- I'm using steel that I get surplus, and there's a wide
range of machinabilities that I'm experiencing; I can certainly see how
using the _right_ steel might make a significant difference. But:

If I take some annealed or normalized 1065 steel (or other 10"something
big" steel), get it to the shape I want, and properly heat treat it, it's
going to be a _lot_ harder than when I started. So assuming that I can
machine it in the first place, then get it to hold its shape (or correct
its shape after the fact) and not crack in the heat treat process, I'm
way ahead.

On the other hand, if I take 12L14, get it to the shape I want, and do
the _very best heat treat in the world_, then -- because of the low
carbon content -- it's not going to be much harder. Right?

What about 1144 or 41L40? Do you get much by heat treating these? How
easy are they to machine compared to 12L14? Why isn't there a 12L50?

I've heard tell that 1144 isn't as strong as other steels of similar
carbon content -- true? What about the mechanical properties of 41L40
after heat treat?

I'm basically looking for a steel that'll be suitable for model airplane
crank shafts. The advice that I get from the hobby builders of model
airplane engines is "use 12L14 and don't crash". I'm not going to
discount this -- but it'd be nice to be able to do something on par with
what I buy at the store. So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

Id use 4140 or 4340 (annnealed) or (pre hard) for model airplane cranks.

Its not all that hard to machine, even with a small weak lathe. Just
dont take huge bites when cutting it. Take your time.

Heat treating is easy enough when you are done and any finish work can
be done easily enough.

Id NOT use 12L14 for this application. No way.


Gunner





--
"The danger to America is not Barack Obama but a citizenry
capable of entrusting a man like him with the Presidency.
It will be far easier to limit and undo the follies of an
Obama presidency than to restore the necessary common sense
and good judgment to a depraved electorate willing to have
such a man for their? president.. Blaming the prince of the
fools should not blind anyone to the vast confederacy of
fools that made him their prince".

On Mon, 29 Aug 2011 18:11:16 -0700 (PDT), "
wrote:

On Aug 29, 5:20*pm, Tim Wescott wrote:


I'm basically looking for a steel that'll be suitable for model airplane
crank shafts. *The advice that I get from the hobby builders of model
airplane engines is "use 12L14 and don't crash". *I'm not going to
discount this -- but it'd be nice to be able to do something on par with
what I buy at the store. *So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

--www.wescottdesign.com

Take a look at Stressproof. It machines fairly well and has pretty
good mechanical properties without requiring heat treatment. It is a
premium 1144.

http://www.niagaralasalle.com/product-stressproof.html

Dan

Another good choice!

Gunner

--
"The danger to America is not Barack Obama but a citizenry
capable of entrusting a man like him with the Presidency.
It will be far easier to limit and undo the follies of an
Obama presidency than to restore the necessary common sense
and good judgment to a depraved electorate willing to have
such a man for their? president.. Blaming the prince of the
fools should not blind anyone to the vast confederacy of
fools that made him their prince".

For me, the free machining leaded steel 12L14 is very easy to cut, but
bad for lapping together parts, because is galls so quickly.

For me, the tool steel, annealed 4140 is easy to drill, until the high
speed drill gets dull, and then the 4140 gets locally hard. I have to
order a carbide drill of that size to cut through the hard spot.

For me, 1018 steel is the go to steel.

On Tue, 30 Aug 2011 11:20:26 -0700 (PDT), "
wrote:

For me, the free machining leaded steel 12L14 is very easy to cut, but
bad for lapping together parts, because is galls so quickly.

For me, the tool steel, annealed 4140 is easy to drill, until the high
speed drill gets dull, and then the 4140 gets locally hard. I have to
order a carbide drill of that size to cut through the hard spot.

For me, 1018 steel is the go to steel.


I've most certainly workhardened a spot in 4140. But its not that
bad. Just sharpen the drill and go real slow with oil till you get a
couple chips. Then sharpen the drill again. After learning this the
hard way, I watch tool condition pretty close. Far easier to not get
in trouble
Karl

In article ,
Ned Simmons wrote:

On 30 Aug 2011 01:55:38 GMT, "DoN. Nichols"
wrote:

On 2011-08-29, Tim Wescott wrote:


I'm basically looking for a steel that'll be suitable for model airplane
crank shafts. The advice that I get from the hobby builders of model
airplane engines is "use 12L14 and don't crash". I'm not going to
discount this -- but it'd be nice to be able to do something on par with
what I buy at the store. So, basically, something that's easy to
machine, but that'll harden up to something between a grade 5 bolt and a
grade 8 bolt.

I don't think that you will find both "easy to machine" and
Grade 5 to Grade 8 bolt hardness in the same metal.


"Stressproof" (a modified 1144) has a yield around 100ksi, about
halfway between grade 5 and grade 8 screws. It isn't as easy to
machine as 12L14, but it's not bad considering its strength. This
table rates it about the same as 1018, which seems about right.
http://www.carbidedepot.com/formulas-machinability.htm

McMaster carries generic Stressproof on p. 3633.

I made my replacement vertical mill drawbar out of 1144 stressproof. It
was easy to machine on the Clausing 5914, although the machining forces
were about double those of 1018.

Joe Gwinn

Tim Wescott wrote:

On the other hand, if I take 12L14, get it to the shape I want, and do
the _very best heat treat in the world_, then -- because of the low
carbon content -- it's not going to be much harder. Right?

It isn't going to get much harder, you would have to case harden it (carbon packing), and
it doesn't weld well. Sure is nice to turn though. I have a bunch of barends from when
we ran a Index G200.

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