I made several tight toleranced parts yesterday. All of them about .2800"
round with a number of different diameter steps that call for tolerances
down to .0003. I made them from W-1 drill rod. The parts turned out nicely
with all fits and tolerances just right. Then I hardened them...

Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. Of course, they are now unusable. I hardened
them by heating to bright red then quenching in water.

I'm wondering what I can do the next time to avoid this problem? Could it
be that I heated the part too hot before quenching? Does W-1 always have
this problem and/or is there a better steel to use? Thanks for all
suggestions.

Robert

For tolerances that tight you will need to turn the part slightly
oversize, harden, then grind to the finish dimension.
Bugs

I was afraid you were going to say that since I don't have a toolpost
grinder or other means to grind the final dia. after hardening. Any other
ideas?

Robert

"Bugs" wrote in message
oups.com...
For tolerances that tight you will need to turn the part slightly
oversize, harden, then grind to the finish dimension.
Bugs

Siggy wrote:

Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. Of course, they are now unusable. I hardened
them by heating to bright red then quenching in water.

Generally, steel will always change it's size when hardened. This is due
to the fact that the carbon-atom changes it's position in the crystal.
But there are special steels that will not react that much when
hardened. I think they are called "invar". But I can't give you any
numbers because they are hard to obtain and also we (Krauts) have an
other nomenclature.

In your case, I would just lapp/oilstone the parts down.


Nick
PS: Thanks for another set of nice plans in MEB!
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

"Siggy" wrote in message
m...
I made several tight toleranced parts yesterday. All of them about .2800"
round with a number of different diameter steps that call for tolerances
down to .0003. I made them from W-1 drill rod. The parts turned out
nicely
with all fits and tolerances just right. Then I hardened them...

Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. Of course, they are now unusable. I
hardened
them by heating to bright red then quenching in water.

I'm wondering what I can do the next time to avoid this problem? Could it
be that I heated the part too hot before quenching? Does W-1 always have
this problem and/or is there a better steel to use? Thanks for all
suggestions.

Robert

Hardening carbon steel converts the phase to martensite, which is less dense
than the unhardened phases (ferrite, mostly). Thus, it expands when you
harden it.

Usually such precision parts are turned, hardened, and then ground. In a
hobby shop, they may be lapped after hardening, rather than ground.

--
Ed Huntress

"Siggy" wrote in message
om...
I was afraid you were going to say that since I don't have a toolpost
grinder or other means to grind the final dia. after hardening. Any other
ideas?

Robert


If you're really good/lucky, you might be able to sand them to the proper
size. Be careful, they will heat up while you sand.

In article Vk_gf.23339$q%.3454
@newssvr12.news.prodigy.com,
says...
I made several tight toleranced parts yesterday. All of them about .2800"
round with a number of different diameter steps that call for tolerances
down to .0003. I made them from W-1 drill rod. The parts turned out nicely
with all fits and tolerances just right. Then I hardened them...

Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. Of course, they are now unusable. I hardened
them by heating to bright red then quenching in water.

I'm wondering what I can do the next time to avoid this problem? Could it
be that I heated the part too hot before quenching? Does W-1 always have
this problem and/or is there a better steel to use? Thanks for all
suggestions.

All tool steels will change to some degree when hardening.
W1 is about as bad as it gets. Following proper hardening
and tempering procedure will minimize the problem. A2 is
probably the most stable among the more common alloys, but
requires more care and higher temps to harden. O1 is pretty
forgiving and falls somewhere in the middle.

You may be able to pull this off with a little
experimentation and careful control of your hardening
process. If you're heating by eye with a torch it's going
to be tough. Are you aware of the magnet test for the
steel's transition temperature?

How hard do the parts need to be?

Ned Simmons

On Wed, 23 Nov 2005 13:42:13 GMT, "Siggy"
wrote:

I made several tight toleranced parts yesterday. All of them about .2800"
round with a number of different diameter steps that call for tolerances
down to .0003. I made them from W-1 drill rod. The parts turned out nicely
with all fits and tolerances just right. Then I hardened them...

Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. Of course, they are now unusable. I hardened
them by heating to bright red then quenching in water.

I'm wondering what I can do the next time to avoid this problem? Could it
be that I heated the part too hot before quenching? Does W-1 always have
this problem and/or is there a better steel to use? Thanks for all
suggestions.

Robert



A Dremel is easy to improvise as a tool post grinder. I can shoot you
some pics if you need a looksee.
DE

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On Wed, 23 Nov 2005 08:08:37 -0700, DE
wrote:


A Dremel is easy to improvise as a tool post grinder. I can shoot you
some pics if you need a looksee.
DE

Pardon me for butting in here but I'd love a looksee. Email pics to
lprince1 at comcast dot net ?

Thanks

(clip) Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. (clip)
^^^^^^^^^^^^^^^^^^^
This may sound like a dumb question to those in the know, but why can't you
turn the parts about .0006 under, and then heat treat? Would it be a
surface finish problem, or distortion or something I haven't thought of?
Just curious.

This may sound like a dumb question to those in the know, but why can't
you
turn the parts about .0006 under, and then heat treat? Would it be a
surface finish problem, or distortion or something I haven't thought of?
Just curious.



The main problem is that the growth will be nearly impossible to predict. In
some metals (like H-13) some areas may actually shrink. The growth usually
is proportional to the size of the part, where small parts grow very little,
and larger parts grow more. In most materials, you can count on around
..0007" growth per inch. Usually, depending on the quality of the heat
treatment process, you can expect different amounts of growth in different
areas. Plan on the part coming back out of round. If you're trying to hold a
..0003" tolerance, you better count on machining after heat treat.

I don't have photos to post, but my Dremel adapter is just a block of
aluminum. I fitted the bottom of the block into the compound slot and
drilled a vertical hole for a hold-down bolt, then turned the compound
parallel to the ways and used the lathe to drill & bore a horizontal
hole that accepts the neck of the Dremel. It's shaft is automatically
at lathe center height and the compound screws feeds it straight in.

jw

Siggy wrote:

I was afraid you were going to say that since I don't have a toolpost
grinder or other means to grind the final dia. after hardening. Any other
ideas?

Robert

"Bugs" wrote in message
oups.com...

For tolerances that tight you will need to turn the part slightly
oversize, harden, then grind to the finish dimension.
Bugs




http://modelenginenews.org/techniques/needles.html

Nice picture of a dremel tool made into a tool post grinder. The author
mentions that the bearings aren't up to real precision work, but I'm
thinking they could be upgraded.

One of these days I gotta get me a tool post grinder...

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

DE wrote:

On Wed, 23 Nov 2005 13:42:13 GMT, "Siggy"
wrote:


I made several tight toleranced parts yesterday. All of them about .2800"
round with a number of different diameter steps that call for tolerances
down to .0003. I made them from W-1 drill rod. The parts turned out nicely
with all fits and tolerances just right. Then I hardened them...

Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. Of course, they are now unusable. I hardened
them by heating to bright red then quenching in water.

I'm wondering what I can do the next time to avoid this problem? Could it
be that I heated the part too hot before quenching? Does W-1 always have
this problem and/or is there a better steel to use? Thanks for all
suggestions.

Robert




A Dremel is easy to improvise as a tool post grinder. I can shoot you
some pics if you need a looksee.
DE

Could you put them in the drop box, please?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

"Siggy" wrote in message
m...
I made several tight toleranced parts yesterday. All of them about .2800"
round with a number of different diameter steps that call for tolerances
down to .0003. I made them from W-1 drill rod. The parts turned out
nicely
with all fits and tolerances just right. Then I hardened them...

Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. Of course, they are now unusable. I
hardened
them by heating to bright red then quenching in water.

I'm wondering what I can do the next time to avoid this problem? Could it
be that I heated the part too hot before quenching? Does W-1 always have
this problem and/or is there a better steel to use? Thanks for all
suggestions.

Robert


Robert,
Lacking proper grinding capabilities, you should be able to spin polish the
hardened parts to achieve size. It's the common way to accomplish close
tolerance work, heat treated or not, under such a circumstance. It
requires a little skill to achieve without rounding edges, but it's
certainly possible, assuming the turned lengths are not short.

Harold

"Harold and Susan Vordos" wrote in message
...

Robert,
Lacking proper grinding capabilities, you should be able to spin polish
the
hardened parts to achieve size. It's the common way to accomplish close
tolerance work, heat treated or not, under such a circumstance. It
requires a little skill to achieve without rounding edges, but it's
certainly possible, assuming the turned lengths are not short.


Harold,

Do you have specific pointers on how to do this? I don't specifically have a
need to know, but I'm sure other would appreciate some insight.

Things like using a stone vs. emery cloth/paper, grits, SFPM, and hand
technique. Sounds like a neat trick.

Regards,

Robin

On Wed, 23 Nov 2005 11:16:53 -0800, Tim Wescott
wrote:

One of these days I gotta get me a tool post grinder...

Pneumatic die grinder and a couple of hose clamps...

OK...I'll ask a dumb question...Isn't drill rod already pretty hard? How
much harder could you make it? Anyone know the Rc hardness of drill rod ?
Thanks

"Dave Lyon" wrote in message
news:w91hf.352861$084.317296@attbi_s22...

This may sound like a dumb question to those in the know, but why can't
you
turn the parts about .0006 under, and then heat treat? Would it be a
surface finish problem, or distortion or something I haven't thought of?
Just curious.



The main problem is that the growth will be nearly impossible to predict.
In
some metals (like H-13) some areas may actually shrink. The growth usually
is proportional to the size of the part, where small parts grow very
little,
and larger parts grow more. In most materials, you can count on around
.0007" growth per inch. Usually, depending on the quality of the heat
treatment process, you can expect different amounts of growth in different
areas. Plan on the part coming back out of round. If you're trying to hold
a
.0003" tolerance, you better count on machining after heat treat.

You're welcome! Out of curiosity, how in the heck did you know those plans
were mine?

Robert


""Nick Müller"" wrote in message
...
Siggy wrote:

Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. Of course, they are now unusable. I
hardened
them by heating to bright red then quenching in water.

Generally, steel will always change it's size when hardened. This is due
to the fact that the carbon-atom changes it's position in the crystal.
But there are special steels that will not react that much when
hardened. I think they are called "invar". But I can't give you any
numbers because they are hard to obtain and also we (Krauts) have an
other nomenclature.

In your case, I would just lapp/oilstone the parts down.


Nick
PS: Thanks for another set of nice plans in MEB!
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

"Robin S." wrote in message
. ..
snip---

Do you have specific pointers on how to do this? I don't specifically have
a
need to know, but I'm sure other would appreciate some insight.

Things like using a stone vs. emery cloth/paper, grits, SFPM, and hand
technique. Sounds like a neat trick.

Regards,

Robin


I've always taken advantage of the highest spindle speed available to me,
secure in the knowledge that grinding demands high surface speed. The
faster the surface speed, the better (and faster) abrasives perform.
Heating, naturally, is a problem.

Typical procedure for me has been to machine to roughly .0005" oversize,
then polish for size and finish. Constant cooling and measuring is required
when shooting for a tight tolerance. Seal and bearing fits are a good
example of where I use this process.

Grits? Depends on how much is to be removed and the finish
required/desired. I've used as coarse as 60 and as fine as 600.
Regardless of where you start, though, it's smart to use them progressively,
which eliminates polished surfaces with scratches.

What works very best is strip, which you hold by the ends. You can spot
polish by using an edge, but care must be exercised, otherwise it's easy to
create undercuts. You also must learn to avoid edges, which are easily
rounded off. Short turns are very difficult for that reason. I must
confess, the majority of the polishing I've done has been on soft materials
(anything machinable, not requiring a grinder). With rare exception, I've
had the use of precision grinders for hardened work. Still, the principles
are the same, it just takes a little longer.

It's easy for strip to get wound around a spinning object, so care must be
exercised to avoid wrapping well enough for the strip to do so. Keeping the
ends apart helps avoid problems. If you find you're applying pressure at
the part with fingers instead of holding the ends, the strip is inclined to
wrap around, dragging your fingers in with it. Be careful. Never permit
the strip to complete a circle.

I never use files, which make it easy to lose roundness, and are generally
too aggressive for fine work when the part is spinning. I've always avoided
using anything rigid (stones, for example), with one exception. I ground
a set of stepped plug gages for a defense installation, but had to use a
tool post grinder. There was no precision grinder in that particular
facility. I ground the diameters on top tolerance, then followed up with
polishing cloth, quite fine, and placed between a pair of parallels. My
purpose was strictly to bring up the finish, which, typical of a tool post
grinder, wasn't very good. It took only a tenth or so to enhance the
finish. The parts had a lapped appearance. To be perfectly honest, I was
surprised, and impressed.

Not much guidance, I realize. I think each of us develop what works for
us------which is what I did. I don't recall anyone training me to achieve
the end result in the way I do.

Incidentally, parts so created will pass extensive inspection procedures.
It's not a hack way to go, not if applied well. .

Good luck!

Harold

Siggy wrote:

Out of curiosity, how in the heck did you know those plans
were mine?

You told it once here. And it's not hard for me to remember what Siggy
stands for. :-)


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

On Wed, 23 Nov 2005 15:11:36 -0800, "Kelly Jones"
wrote:

OK...I'll ask a dumb question...Isn't drill rod already pretty hard?

No, it's soft. That way you can machine it however it's needed, then
harden it afterwards.

"Nick Müller" wrote in message
...

Generally, steel will always change it's size when hardened. This is due
to the fact that the carbon-atom changes it's position in the crystal.
But there are special steels that will not react that much when
hardened. I think they are called "invar". But I can't give you any
numbers because they are hard to obtain and also we (Krauts) have an
other nomenclature.

Invar, IIRC, is a special cast-iron alloy that has a near-zero coefficient
of thermal expansion. Moore Special Tool used it for the heads of their jig
grinders.

I wasn't aware that it had special hardening properties. Are you sure you
aren't thinking of its freedom from thermal expansion, in use?

--
Ed Huntress

Ed Huntress wrote:

Invar, IIRC, is a special cast-iron alloy that has a near-zero coefficient
of thermal expansion. Moore Special Tool used it for the heads of their jig
grinders.

I wasn't aware that it had special hardening properties. Are you sure you
aren't thinking of its freedom from thermal expansion, in use?

No, I'm not that sure. But I know, that there do exist special steels
that do not change their sizes (or _very_ little) if hardened. They are
used for stamp and die making. Roechling has them (among others). And I
_think_ they are called invar, but have no source at hand to verify
that.

OK, I did a quick Google. Invar is not cast. But also I didn't find that
property of not changing it's size when hardened. But still it doesn't
change it's size over a big temerature range. It's mostly used for
gauges.

Anyone has a name at hand?


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

Nick Müller wrote:

This is due to the fact that the carbon-atom changes it's position in the
crystal.

This effect/fact (Carbon in steel) shows, that steels having very litte
C-content should be better. They will have Cr, Mo, Mb etc. There is a
C-equivalent that says that you can replace C with other elements
(metals). If you want, I can dig for that formula.

Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

"Nick Müller" wrote in message
...
Ed Huntress wrote:

Invar, IIRC, is a special cast-iron alloy that has a near-zero
coefficient
of thermal expansion. Moore Special Tool used it for the heads of their
jig
grinders.

I wasn't aware that it had special hardening properties. Are you sure
you
aren't thinking of its freedom from thermal expansion, in use?

No, I'm not that sure. But I know, that there do exist special steels
that do not change their sizes (or _very_ little) if hardened. They are
used for stamp and die making. Roechling has them (among others). And I
_think_ they are called invar, but have no source at hand to verify
that.

OK, I did a quick Google. Invar is not cast.

This will be a big surprise to the precision machine tool builders,
especially Moore, who used Invar castings for over 30 years. g

It's probably one of those metals that you cast or not, depending on what
you need. I've never read about its mechanical properties so it may not
matter. The zero-temperature-expansion coefficient is its reason for
existing. It is a b*tch to machine, however.

--
Ed Huntress


But also I didn't find that
property of not changing it's size when hardened. But still it doesn't
change it's size over a big temerature range. It's mostly used for
gauges.

Anyone has a name at hand?


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

"Ed Huntress" wrote in message
...
"Nick Müller" wrote in message
...
Ed Huntress wrote:

Invar, IIRC, is a special cast-iron alloy that has a near-zero
coefficient
of thermal expansion. Moore Special Tool used it for the heads of
their
jig
grinders.

I wasn't aware that it had special hardening properties. Are you sure
you
aren't thinking of its freedom from thermal expansion, in use?

No, I'm not that sure. But I know, that there do exist special steels
that do not change their sizes (or _very_ little) if hardened. They are
used for stamp and die making. Roechling has them (among others). And I
_think_ they are called invar, but have no source at hand to verify
that.

OK, I did a quick Google. Invar is not cast.

This will be a big surprise to the precision machine tool builders,
especially Moore, who used Invar castings for over 30 years. g

It's probably one of those metals that you cast or not, depending on what
you need. I've never read about its mechanical properties so it may not
matter. The zero-temperature-expansion coefficient is its reason for
existing. It is a b*tch to machine, however.

--
Ed Huntress

I've machined Invar 36 with no difficulties. It's not like titanium, for
example.
What is a bitch is the price. I had bid on the tool in question, but had
the good sense to bid with the Invar provided by the buyer, which they did.
I needed only a small piece, about four square inches, material thickness of
1/2". I was quoted $1,000 for a piece 12" square, and couldn't buy it any
smaller. Buyer be ware!

Harold

I'd agree with several other posters and polish to size.
But, you didn't say anything about tempering after hardening. It sure
would be a shame to go to all that trouble and then have the edges chip
off or worse, due to brittleness. I can tell you from personal
experience that your piece of hardened W1 won't even survive a fall to
the floor in the fully hardened state.

Pete Stanaitis
-------------------




Siggy wrote:

I made several tight toleranced parts yesterday. All of them about .2800"
round with a number of different diameter steps that call for tolerances
down to .0003. I made them from W-1 drill rod. The parts turned out nicely
with all fits and tolerances just right. Then I hardened them...

Problem is that after hardening, the diameter of the parts increased
anywhere from .0005 to .0007. Of course, they are now unusable. I hardened
them by heating to bright red then quenching in water.

I'm wondering what I can do the next time to avoid this problem? Could it
be that I heated the part too hot before quenching? Does W-1 always have
this problem and/or is there a better steel to use? Thanks for all
suggestions.

Robert