which tool steel

Those of you that follow this NG closely may know I grow apples for a living...
I use the "Limb Lopper" brand pruner to prune my orchard. This is the
Cadillac of pruners. Like all too many quality made in USA products, it has been judged too expensive and now you can only get inferior products made off shore. The pruner is out of production and parts will soon not be available.
The shear and hook part of the pruner are wear items that must be re-sharpened every few hundred trees. After 10,000 or so trees you need to replace them. My son is writing up a CNC program to machine the parts after scanning in a coordinate measuring machine.
These two parts are made out of a tool steel with incredible properties. The material is as resistant to being bent as the best quality wrenches. I have never broke or bent a hook and shear. Yet, the steel is soft enough to be sharpened with a file.
I need to determine exactly what this material is and its likely heat treatment. I want to get this exactly right, not just guess. How would I go about finding out what material to use?
Karl
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Karl Townsend wrote:
snip
. How would I go

People with a lot of experience can grind a sample of the metal and tell you the alloy family by viewing the sparks. The resiliency tells me it may be a high vanadium steel such as the M series used to make good drill bits. Perhaps a metallurgist could perform a tensile test and a Rockwell hardness test and cross reference the results against a catalogue of steels with the same tensile strength at that hardness.
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Find someone with a mass spectrograph. This is not so outlandish a proposal as you think. A local iron foundry I know of has one to do quality control as well as identify castings they need to duplicate. I doubt that if you had it done commercially by an engineering/inspection firm it would be more than 100 dollars. Any friends in a college science program? Randy
message Those of you that follow this NG closely may know I grow apples for a living...
I use the "Limb Lopper" brand pruner to prune my orchard. This is the Cadillac of pruners. Like all too many quality made in USA products, it has been judged too expensive and now you can only get inferior products made off shore. The pruner is out of production and parts will soon not be available.
The shear and hook part of the pruner are wear items that must be re-sharpened every few hundred trees. After 10,000 or so trees you need to replace them. My son is writing up a CNC program to machine the parts after scanning in a coordinate measuring machine.
These two parts are made out of a tool steel with incredible properties. The material is as resistant to being bent as the best quality wrenches. I have never broke or bent a hook and shear. Yet, the steel is soft enough to be sharpened with a file.
I need to determine exactly what this material is and its likely heat treatment. I want to get this exactly right, not just guess. How would I go about finding out what material to use?
Karl
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Karl Townsend wrote:

I thought Felco was the Cadillac of pruners? Least wise they're priced like a Cadillac.
http://www.felcostore.com/index.jsp

My educated guess would be 4140.

--
Regards,
Steve Saling
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The pruners we used to use in our orchard didn't rust.
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Good choice, but H-13 may be a bit better. I know it is more stable in heat treat.

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Garlicdude said: "My educated guess would be 4140".
I'm inclined to go along with you, Karl, especially if its tempered to around Rc 50 or so.
A tool & die shop I had as a client made envelope dies from 4140 and tempered as I stated. I was taken aback at this use of this steel, but, the cutting edge lasted long enough for their customers to be happy.
BTW: Envelope and label dies are used to stamp/cut labels and small envelopes from a thick stack of paper. The paper is placed on a wooden board into a press, the die in the shape of a cookie-cutter is placed on top of the paper stack, and the press operated. Voila, a stack of envelopes or labels result. Crude but effective. For large labels or envelopes the die is bent-up from 1/2" x 3" proprietary steel bars, heated and welded into a closed form. Think of steel rule dies, only MUCH more substantial.
I think this steel would work well in the tree-trimming business. Best of all: it is cheap and the heat treatment is a cinch. The heating ought to be done in a furnace, though, to ensure uniform properties throughout.
Trust this helps.
Wolfgang
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The hook and shear on the felco air pruner are about 1/2 the size of the ones on the Limb Lopper. Won't go around as big a branch. The felco air cylinder is about 2" diameter vs. 3" for the limb lopper. Which one has more power? The felco air cylinder is up at the cutting head making it heavy on the end (wears you out pruning 40 hours a week), the limb lopper has the cylinder down at your hands.
In short, if you put the Limb Lopper shear on any branch under 1 1/2" and pull the trigger, its gone. And they don't break down, everything is well engineered.
Of course the Felco lists at $500. When you could still get a Limb Lopper, they were $1500.
To all the great suggestions. I'll make my prototypes out of 4140, D2, and H13. If none of these meet my needs, I'll start looking for a place to analyze the metal.
Karl
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Karl Townsend wrote:

Karl, I have a small home orchard. Four citrus, two apple trees, half a dozen stone fruit trees. I also have about 20 English walnuts and 50 almond trees. On the Felco thing I was pulling your leg. All I've ever used is their hand pruner, and thought it expensive at close to $50, compared to the usual home improvement center stuff.
I'd like to add a Fuji, my new favorite apple, to my orchard.
Have fun with that D2. :)
--
Regards,
Steve Saling
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message

Karl, I was watching the Discovery channel just a couple of days ago. The guy in a metal recycling business had a gun that zapped a piece of metal with a laser beam and did a spectrographic analysis of the light emitted. They said it would identify some 7,000 different alloys! Got a big scrap yard around?
Gary H. Lucas
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"Gary H. Lucas" wrote:

Yup, Naparano scrap yard in Newark NJ has one of these.Also, most foundries have the ability to run tests on the metals they pour using a spetroscopic instrument.
John
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priced
the
air
has
lopper
and
well
Lopper,
and
to
in
yard
And where were you when I had logged the ## of that "knife steel" on IRC ???
Alas, its probly too late now...
<sigh>
--
SVL




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I missed telling everyone a MAJOR point. Its magnetic and will rust, but very slowly. I have some old shears that sat in a shed for years with slight rusting. (I watch Ebay for limb lopper and buy them all)The shears in daily use show no rusting.
Of these candidates, do any rust but slowly?
stainless 440C H13 D2 4140 (I ruled this out - I know it rusts faster )
Karl
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Karl Townsend wrote:

Yes, it rusts when not full hard. Is magnetic

I don't know

Yes, it rusts slowly
There is a 440A and 440B also. I wouldn't use any 440 for this, not very tough, breaks easy. There is a 420 that may work. Used for plastic extrusion dies.
D2 is abrasion resistant would would not file well, even fairly soft. Other than that, it is a good steel for this application with an RC around 55
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Don't forget 455 stainless, it come up to about 55 Rc
Beege
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Karl Townsend wrote:

Karl, Steels in general rust less when heat treated, and the higher they are to their maximum hardness the less they rust.
I still think 4140 is the best choice for your job. 440 SST, H13, and D2 if hardened to anywhere near their max will be difficult to sharpen with a file as you stated in your original post. I doubt that the original manufacture used something as "exotic" as the above mentioned steels.
Also most of the loper blades that I have seen looked to be forged, which gives them very different properties than a blade made from bar stock.
--
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Steve Saling
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Garlicdude wrote:

Good point. A forged blade or wrench will perform unlike anything machined from stock due to the grain structure from the material flow.
With that said, some shapes (like a lawn mower blade) do not require forging to obtain the advantages of grain direction because they can be cut and formed so the grain of the steel flows along the length of the part. The rolling process for the raw material does the same thing as forging (for that shape). The cutting edge of the shear may be the same way, so long as you respect the grain direction of the material you start with.
Years ago while I was in college, I worked as a hack machinist for a manufacturing company in Raleigh. A linkage in a hydraulic assembly in a tube bender failed due to metal fatigue. I replaced it with a piece of unhardened tool steel. O1 probably. It was a very pretty piece and I was so proud to make this pretty part and get production going on that tube bender again. I expected it to be way stronger than the cold rolled steel part it replaced.
I was very surprised when it failed in less than one shift. I had the grain directing off by 90 deg. And tool steel is not very tough. I made another shaft out of some ugly old hot rolled steel and to my knowledge it is working to this day.
Grain direction man.
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...

I learn something everyday on this NG. I knew wood had grain, didn't know that about steel. The original is forged, can't duplicate that. The outline shape will be laser cut out of bar stock, I'll be sure and have the length of the part line up for maximum strength. My son is having this done as a government job where he works. He asked me to provide the stock. I'll try three of the best candidates for a trial.
Thanks for all the help.
Karl
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On Mon, 06 Mar 2006 17:53:55 GMT, "Karl Townsend"
<snip>

Hi Karl,
If you come up with a version suitable for manual use with handles I would be interested in a set. Just the shear and hook, I can make up handles of some sort.
A good heavy duty hand lopper is hard to come by now days. Most of them have weak parts and take very little abuse, err hard use...
Keep me in mind if your parts aren't too expensive.
--
Leon Fisk
Grand Rapids MI/Zone 5b
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Let it analize. It costs a bit. Here in Germany, you would have to pay 100 ... 150 EUR (150..200 US$). They do spectroscope the material and name you the alloys that do have the same mixture. A hardness-test will reveal the heat-treatment.
Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
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