which tool steel

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.

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

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

I thought Felco was the Cadillac of pruners? Least wise they're priced like a Cadillac.

My educated guess would be 4140.

Let it analize. It costs a bit. Here in Germany, you would have to pay

Nick

The pruners we used to use in our orchard didn't rust.

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

D2 may be a viable option. You can mill it, and without saying too much, a previous employer used custom-milled knives made from D2 to slice sheet steel parts. I didn't make very many knives, but they sure made a lot of parts with the knives I did make. HTH.

Later,

Charlie

Good choice, but H-13 may be a bit better. I know it is more stable in heat treat.

A friend with a wire edm shop had a job making pruner blades out of solid carbide. It was for a pneumatic industrial pruner, I assume this is the same application.

Fred

"Karl Townsend" wrote Snip

The pruner may be out of production but the factory may still be open with other products in the works. Drop a dime. Tom

SNip

Is there a patent # on the pruner? Try the USPO web site. Tom

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

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. :)

If the company is still in existence, why not give then a call and ask for the specs of the blade material they used. It'll probably take some perseverence to get to the right department. Start with tech service or engineering.

While your talking with the company, buy as many replacement blades as you can.

I'd agree with that, but are you sure it is a tool steel? Does it rust? If it is soft enough to sharpen with a file I would wonder if it is just a carbon steel, fairly heavily tempered. I'd agree with some of the other posters though. Try and match the Rockwell hardness (small engineering workshop or technical college). There are hand-held instruments for analysing steels which you might find at a large engineering works. The older, low tech ones strike an arc and you measure the spectrum (some skill needed!) but I saw one a couple of years back which did an X ray analysis and confirmed very quickly and easily the stem and seat material of a 1 inch valve which had failed. Very impressive, cost about $10,000 though.

You could always put some stelite steel where it cuts, like they do for aircraft valves.

Just part of the valve face is stellite. You can see the layer when you regind then. Tough steel.

xman

"Karl Townsend" wrote in message news:TG_Of.3273$ snipped-for-privacy@newsread3.news.pas.earthlink.net...

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

I think you are trying too hard to find the same metal. Do a Rockwell hardness test and then pick some steel that is easy to heat treat to the same hardness. Or maybe a steel as stressproof that is already that hardness.

When in doubt start with O-1 Medium wear, medium toughness, medium distorsion in heat treat, and high machinability. Normal range of hardness C 58 to 62.

Dan

Karl Townsend wrote: