The results of my latest flex test are?

I dont think you would have to bump the tang to do a 180 from original position.
Would not just bending it straight down be the true 180?
However I dont think anyone counts a 180 like that...LOL
 
Allan,

You mentioned not believing in the concept of a fully hardened blade for outdoor use, but I would disagree. I have started making an O1 steel outdoor knife with a 4" long blade 1/8" thick and about 1" wide. I fully harden these blades per reccomendations of Kevin Cashen, Tim Z. and others. I interrupt quench and temper to 59-60 RC and have been able to pound these blades into a tree 2" ( I call them my dog and pony show tests!), blade horiz. to the ground and stand on the handle and flex it. Total wt. is about 170 lbs. and the blades don't break or take a set.

If I've learned nothing else from this forum, I think we should be matching our steel to usage and our heat treat to the steel, rather than the other way around.

I am not trying to start a pissing match just looking at all options.

Rod
 
mtnsct said:
Allan,

You mentioned not believing in the concept of a fully hardened blade for outdoor use, but I would disagree. I have started making an O1 steel outdoor knife with a 4" long blade 1/8" thick and about 1" wide. I fully harden these blades per reccomendations of Kevin Cashen, Tim Z. and others. I interrupt quench and temper to 59-60 RC and have been able to pound these blades into a tree 2" ( I call them my dog and pony show tests!), blade horiz. to the ground and stand on the handle and flex it. Total wt. is about 170 lbs. and the blades don't break or take a set.

If I've learned nothing else from this forum, I think we should be matching our steel to usage and our heat treat to the steel, rather than the other way around.

I am not trying to start a pissing match just looking at all options.

Rod
Click to expand...

Did you say 1/8"? Wow. I wouldn't have thought steel that thin would take that.

Allan,
What kind of finish did you have on your blade? I'd think having a handrubbed finish with the scratches running lengthwise would be best.
If you left a belt finish with the scratches perpendicular to the edge, it might create stress risers and you're blade would fail sooner.
 
Phillip Patton said:
Allan,
What kind of finish did you have on your blade? .
Click to expand...

I was finishing the blade on the buffer when I looked at it, and just hated the shape.

The curves just didn't look cool.
Yes I could have fixed it, but that would have meant grinding into the harden areas of the cutting edge, and that would mean I should anneal it first.

And that sounded like a lot of work.
So I decided to break it....
The bend test was just a way for me to break a crappy knife and learn from doing it.

I had sanded the blade up to 400 grit I think, then I used a rough buffing , and then went to green crome to get a mirror finish.
 
mtnsct said:
I have started making an O1 steel outdoor knife
Click to expand...
I dont know anything about 01 steel.
I dont even know what the term "01" means.

But with the steel Im useing, (ball bearing) I cant get away from the fact that if I try to make the blade fully hard, that I end up with a blade that I cant trust.

If this blade that failed on me yesterday was fully hard, (no matter the clay-coating attempt) then this is the 2nd fully hard blade I have tested from my bearing steel and it's the 2nd fully hard blade that totally failed to act like I wanted.

I dont want a knife that will snap in a guy's hands just because he might apply 60 foot lbs of force to the handle.

When I was yanking down on the blade and it snapped, it didnt seem to me at the time like 60 foot lbs was too much to ask for a working man's blade to handle.

I have no idea how my fully hard 52100 blade compares to others who have also done the same type of torque test, but I would be interested to know that...

I cant bang my blade into a tree in my backyard and think the results can be compared to your 01 tree test, because there way too many things that could be different that would screw up the results.
But if a guy with a 01 blade, stuck that blade it into a vice and pulled down on it with a torque wrench and got to 100+ lbs?
Then that would be something to learn...
 
mtnsct said:
and stand on the handle and flex it. Total wt. is about 170 lbs. and the blades don't break or take a set.
Click to expand...
Here is another thing Im not sure about.

I once was at work and I had to get up a wall, so jamed a screwdriver into the wall and it was enough to hold my weight and I used it as a stair to climb out . That screw driver didnt have a bend in it..

But that same screwdriver later bent right over when working on my car when I tried to use it to pop a stuck starter free.

My Question:
If I use a torque wrench and set it to 195 ft lbs, is this going to show me the very same results as if I just carefully stood on the blade?

The Reason I Ask:
I have seen school students build a bridge out of toothpicks that could hold up in the air 500lbs.
Is there any way that pulling down on a torque wrench could be effecting the blade, in a different manner other than just carefully adding dead weight to them?
 
What would I do different on this next blade?

Clearly Im going to dump the idea of the clay-coating.
But what about the tempering?

(I tempered at 400 for 2 hours, allowed to cool outside in the cold porch, then did another 2+ hours in the kitchen oven at 400
then into the freezer overnight.)

The last time I had a blade snap on me during a test a forum member said it was not because of the fully hardened blade, but was because I screwed up the tempering.
Well this time I sure thought at the time I had really nailed well the tempering.
But any blade that snaps at only 65 ft lbs is clearly screwed up somewhere along the line.

65 is not that much torque, dont they tighten car lug nuts about 35-40?
One should have expected more out of a tool.
 
Phillip P.

I am using a scandi grind on the knives which leaves full thickness through a larger portion of the blade ( 1/8" thick for about 2/3's of the blade width). Before I knew that knives were originally designed for cutting:D I had taken an earlier blade and stuck it in a vice and reefed on it with a short cheater bar and broke it because the edge rolled when I tried some batoning.This blade was at 55-56 RC. Since I have brought the hardness up with a fully hardened blade my knives are stronger and hold an edge better. This is important when dealing with the scandi grind since the edge basically tapers down to zero. You need as much strength as you can get at the very edge since it is thinner compared to a double bevel. I don't see why this wouldn't apply with other types of grinds as well.

Allan, you're right about comparing different blades with out known parameters, I'm just trying to point out that a fully hardened blade with proper temper is not necessarily a weak blade. You should go over to Crucibles' website or others that compare steels for toughness, strength etc. Most of their testing is done on fully hardened and tempered steels. Not a direct application to blades but can get you going in the right direction.

O1 is a high carbon, lower to med. alloy tool steel that has been used in many applications including cutting knives. It is often used by custom knife makers because it has good overall qualities of strength, toughness, edge holding and it's easy to work. It also doesn't cost an arm and a leg to buy in flat grownd stock. The O stands for "oil quench".
 
Allan,

I think I am going to back out and hope those more knowledable than myself can answer your questions. I don't want to throw out a bunch of B.S. without even knowing it !?!

Regardless, to figure this stuff out you need to start with a baseline i.e. known steel, HT temp. and process for steel in question, etc. etc.
 
well, I mean I have now tested 3 blades this winter so far.

Two of the blades were fully hard, one was just an edge quench.
(This is assumeing that yesterdays attempt was on a fully hard blade)

So far, the edge-quenched blade has kicked butt over the other two.
I have video of the 90 and 180 bend test and I think that going to be the path I go down in the future.

So far Im not very big on the "Fully hard" concept.
Seems from my testing so far to not be the direction I want to go in.

The thing Im aiming for is a knife that a guy can trust with his life...not something that always comes with a known flaw/snap range.

I would like to know if anyone else that works with 52100 has been able to bump a blade up well over my limit of 65 ft lbs, and not had it snap?

I just dont want to make a blade that snaps.
It should not matter how much force or weight a guy puts on a good knife, it should be able to hang in there, or atleast be in a fixable condition even if it does bend over.

There is a topic on this BLADE FORUM about what is a survival knife?
My idea of that type of knife would be a knife that just will never snap.
You should be able to hook it up to a tow rope and pull a truck out of the ditch with it and not have to worry about it snapping under torque right?
(I saw this done on TV with a Craftsman 1/2 wench a few years ago, and I would always expect any tool to match this level of high performance)
 
[/QUOTE]Also, are you sure these bearings are even made of 52100? If you've got the wrong steel, that could make a huge difference. There was a guy here on the forums offering free analysis services a while back- you might give it a try.[/QUOTE]

Since I'm a Field Technical Engineering Representative for a bearing company, I can help with this one. This information is for Timken bearings. It is probably accurate for other brands, but without having exact part numbers and manufacturer name, it requires some investigation to be sure of the steel type. I can provide this investigative help.

To determine with appproxomately 99% assuredness whether a bearing is made of 52100, use the following guidelines.
A. If the rollers are round balls, they are 52100.
B. If the rollers are barrell shaped, they are most likely 52100. There are
exceptions, such as bearings used in rock crushers and other similar
equipment. Those require case carburized bearings to withstand the
shock loads. But some bearings in rock crushers are still 52100!
c. If the rollers are cylinders, they are most likely 52100. Same as above
for bearings that come out of rock crushers and other similar
equipment. Once again, some bearings in rock crushers are still 52100.
C. If the rollers are tapered (cone shaped with the point lopped off) they
are:
1. 52100 if the part number is 5 digits long and begins with a 3. Such
as in the part number 33217. The outer race with the cage and
rollers will have an X in front of the five digit part number. The
race will also be 52100. The outer race will have a Y in front of the
five digit part number and will also be 52100. Both the inner race
and the outer race will have the word 'ISOCLASS' etched on it.
'ISOCLASS' is a sure fire way to be positive that a tapered bearing
is 52100. The cages of 'all bearings' is made from low carbon steel
or bronze and is not suitable for knife steel.
2. All other part numbers for tapered bearings are most likely low
carbon steel that has been case carburized and is not suitable for
knife steel.

The chances of a tapered bearing being suitable for forging into a knife is rather slim in the United States. We are a case carburized tapered bearing country. In Europe, it's actually the other way around.

If you looked at ArielSalaverria's thread on the Gallery page, he forge welded a spherical bearing into damascus. It will make a good quality knife because it is 52100 steel. He did identify the bearing type incorrectly as a ball bearing, but it didn't matter since both types are made from 52100, as my list above points out. If he had tried this with a tapered bearing, he would not have been able to get the knife hard. The welding and forging processes cause enough carbon loss from the outer layers to end up with only about .2% carbon in the steel, when using a case carburized tapered bearing. Although the cage in his thread was low carbon steel, he had plenty of high carbon steel from the races and rollers to make a good quality damascus.

If anyone has bearings that they'd like to identify the steel type, no matter who the bearing manufacturer was, please PM me or send me an email. Include all the information etched or stamped on the bearing or bearings and I'll help you figure out what the bearing is made out of. I'd be glad to assist.

I hope this helps.

Scott (Ickie) Ickes
 
There is nothing wrong with a full harden blade BUT there was something wrong with the blade that broke. Could be a number of things but most likely too hot at time of quench. Tempered at 450f might have made a huge difference also.

As said above, clay has little or no effect on higher alloy steels.

If I were you and wanted a blade that would bend 180 degs, I would stick with the "torching the edge quench"
 
sunfishman said:
Could be a number of things but most likely too hot at time of quench.

Tempered at 450f might have made a huge difference also.
"
Click to expand...

Ok, I have only a normal magnet to check the heat temp with.
So in your view, if I go to the clear non-magnetic temp, then go just a little hotter for about 30 seconds, is this getting too hot?

This is a real question/problem for me as I have always had trouble "pulling the trigger" and doing the quench at the right time.
I just now started another ball bearing knife. At the moment I write this to you my blade is Normalizing and after that I will do a Anealling in Vemiculite.

When the grinding work on the knife is done I think I plan to just use the old O/A torch and an edge quench.
But Im going to be checking many,many times with the magnet to make sure I dont over heat this blade.


Your suggestion of tempering at 450 is also worth a try....
You never know for sure what range a kitchen oven turns off and on at, so I may just be tempering at too low of oven temp.
 
This information is for Timken bearings. It is probably accurate for other brands, but without having exact part numbers and manufacturer name, it requires some investigation to be sure of the steel type. [/QUOTE]

this morning I ran into a guy at work who says this winter the shop guys plan to change out a bunch of the bearings.

This means that I will be able to name the type of trackhoe the bearings came from, and what part number# the replacement bearings said on the side of the box.
 
I would like some clarifications, as some of this does not seem to add up. What is this "bending vise" you mentioned, how exactly do you get your readings? It seems to me that the numbers you are getting are not directly related to the steel strength, proportional perhaps.

One of the things I have to ask is the 60 ft/lbs of torque, if you were to drive that knife into a wood block/tree 1", and stand on the guard 3" away, it would require 240 lbs to flex it to the same point. (240lb* 1/4ft= 60 ft/lb) personally, that is twice what I weigh. a similar piece(exact same shape) that was only hardened halfway back would probably "give" and begin to bend instead of flex at my weight. So, I guess if you are using a bent to tell you that you are abusing a blade you then can stop before it breaks. Please realize though, once a blade bends, it is damaged goods, it will weaken with each bend. as long as a blade is just flexing, it will retain it's strength.

You mentioned that a 1/2" wrench pulling out a truck? I would use a crowbar myself, not a knife. a crowbar or a wrench has a different cross section than a knife. when you are stressing a piece of steel, a 1/2" square bar has 2x more strength than a 1/4" x 1" bar flexing along the 1/4" side, but only 1/2 the strength of a 1/4" x 1" flexing along the 1" side even though all three bars have the same amount of steel in them. Prybars and wrenches are round to handle the stresses they need to take.
May I also remind you that the torque wrench that you are using is a thoroughly hardened and tempered piece of steel? as you are taking your readings, the wrench is moving through it's elastic range, it is still flexing, it is not breaking, nor is it bending(at which point it would be useless for taking readings anymore)

I am glad that you are testing to make sure that you are producing a good product. I think we all should. But please make sure that you are not trying to test two or more things at a time, it may cloud your results. and please try to compare apples to apples, not oranges. Make sure what the results you are testing mean, and then make a comparison with a similar product, and test.

Ken Nelson
 
IronWolf said:
I would like some clarifications, as some of this does not seem to add up. What is this "bending vise" you mentioned, how exactly do you get your readings?
Click to expand...



You take a normal bench vise and place in the jaws some angle steel thats been nice and rounded so it will not kink the blade.

Then you place the blade of the knife in between the two angles and tighten the jaws of the vise.

Then you have this type of tool that clamps onto the tang area of the knife and has a bolt on the side that a torque wench can attach to.

when everything is tightened and ready to go, you pull down on the torque wench and this can help you test the amount of force needed to bend the blade.

Here is a video clip of my edge-quench blade
http://www.youtube.com/watch?v=7vFAoODVd4o
 
IronWolf said:
You mentioned that a 1/2" wrench pulling out a truck? I would use a crowbar myself, not a knife.
Click to expand...
Well I would drive in the ditch in the first place...

But this idea was in a TV ad for Craftsman tools.
Their idea was that the 1/2 " wench can take whatever we toss at them.

My concept of what we should aim for as good blade smiths is that we are able to make a blade thats a good tool.
A tool thats not going to snap on a guy just because he yanks on it way more than he should have, or attached it to a tow rope.
My knives should be trusted tools

and that 1/2 wrench shure looked like a good tool to me.
 
Allan, One of the points that I was trying to make was that geometry will make as much if not more of a difference when torquing than heat treat, which is why wrenches work the way they do. Assuming the steel and geometry are the same, a edge to back hardened blade and a edge hardened blade will both will flex the same, until the edge hardened blade reaches it's yield point, at that point it will bend, while the other blade still flexes, and will return to true, it will take more force to break the fully hardened blade than it would take to bend the other several times.
 
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