O-1 test base

[T.M.Sanders]

A favor to ask of those out there useing O-1 tool steel. I just finished my first test blade, and got it back from heat treat (1500 deg. for hardening and tempered at 425 deg. for one hour). I'm going to start realy testing it this weekend, it's already passed the brass rod test (???I'm still a little unclear on this one) next I'll see how many cuts I can get on a length of rope. Here is where the problem comes in. I'm realy quite fond of the thing, and would prefer not to do the more destructive tests, such as breaking it. I was woundering if some of you could let me know how your blades preformed on the cutting tests and how youre h.t. compared to mine. Basicaly I'm trying to cheat my way into a test base. I especialy want to see if there is a differenc between a single, double, and triple temper.

Much Thanks to all taht reply

[Ray Rogers]

I quench from 1475 and temper twice for one hour at 400. Tempering at least twice is always a good idea, but more than 3 times doesn't help with most steels.

Edge geometry will have a lot to do with how many cuts you get in a piece of rope and so will the size and type of rope. There is no standard that we can apply across the board among knifemakers that will allow meaningful comparisons between your blade and the next guy's. Manufacturers who own an expensive CATRA machine can do that type of testing but I don't own one and i bet you don't either. You'll just have to build your own data base and compare to other knives when the opportunity presents itself.

Breaking blades will allow you to see the grain structure and evaluate the success of the heat treat process. If the blade is really difficult to break then you are allowed to feel impressed with yourself and confident that your blade should not fail under anything that resembles 'normal' use. So, break one every now and then but be careful and wear eye protection.

Bottom line: if you are happy with the way your blades perform then all you have to do is find out if your customer's are equally happy .......

[Crex]

Always make 2 or 3 blades the same way when trying a "new" steel for the first time.
Give them all the same HT and geometry. Then you can test the heck out of the first one, make adjustments to the second then test it, and still have third to keep as a reminder that you did it right (or wrong). You'll never know what the rest of us are talking about with grain structure, toughness, etc. until you actually break one and see for yourself.
It's part of the job if you are serious about making knives.

[Jason Cutter]

Not an exhaustive test but I just posted some pics in this same subforums. Thought you might get a kick from it. Jason.


http://www.knifenetwork.com/forum/sh...0580post190580

[T.M.Sanders]

Thanks for thwe replys, just a couple fallow up questions.

I just put a finished edge on the knife, and the dedge it took is fabulous. I took it all the way to a razor edge, and then brought it to a nearly miror polish, with no sighn of deteriation at the edge. What, if anything dose this tell me about the grain structure of the steel. I have in the past, on a Bench Made CQC7, brought the edge to the point that the grain structure was beginning to fail.

The other question is how much time can elapse between the intial heat treat and subsequent temperings. I have the heat treat done at work, so I don't want to push my luck asking for extra temperings. I was thinking that I could do them at home in my oven, which begs the question of how acurate dose the temp on a secound or third tempering have to be (+/- 10 deg. ?15 deg?), will my oven be accurate enough to do the job.

[Ray Rogers]

Looks like you probably have pretty good grain structure. Polishing the edge can be fun to try but do some testing with it to see how it cuts. A polished edge isn't always the best edge. They shave well (usually) and they cut OK on anything where the blade can be pushed through the material, like newspaper. But, when the cut requires you to draw the blade polished edges tend to slide off especially on things like nylon rope. Now play fair! You can probably push the blade through nylon rope as long as the blade is still very sharp but when it gets a little dull and you have to draw the blade that's when the difference will show up.

Generally, tempering should be done immediately after the heat treat (or after the cryo if you do that). But, if you must wait then wait and don't worry about it. Get a good thermometer to monitor your oven. You don't want to be more than 10 or 15 degrees off if you can help it.....

[rhrocker]

Jason, thanks for the photo testing tutorial! You must work out with weights!

[mete]

Do the first temper immediately .The as quenched stresses can be very high and the risk of breaking the blade are great with a high carbon steel like O-1. The other tempers are not too critical but I would do them for 2 hours each.Get an oven thermometer.

[Jason Cutter]

Originally Posted by rhrocker

Jason, thanks for the photo testing tutorial! You must work out with weights!

Well, I used to. Nowadays my workouts mainly involve pizza and perhaps occasionally carrying large quantities of Chinese takeaway. I suppose hand rubbing a blade is called exercise...

On the question of delays between tempering, I've never found it a problem if there was a lengthy wait from quench to temper. I haven't yet noticed any problems with grain structure or any such thing. I suppose the main issue is that a fully hardened blade would break easily if accidentally knocked or dropped in the workshop, so the push was to get the tempering done straight away. I could be wrong. Jason.

[mete]

The damage to the blade from not tempering immediately may not be obvious . You can get microcracks ,not visible which then may propagate during use .The higher the carbon and more complex the steel the greater the risk.Don't count on luck !!

[T.M.Sanders]

mete

Are you saying that problem occures between quench and first temper, or that it could occure between secound and third tepers. My first teper will be done at work, it's the subsequent cycles that I'm looking at.

[mete]

The problem is between the quench and first temper. The first temper eliminates the dangerous stresses of the quench so you can wait on the second and third tempers.

[T.M.Sanders]

(Hveing Had reached the end of this post, I have returned to warn you that it dose get a bit long, and to appologize for that; sorry, I just don't know when to stop.)

The results on my first test blade are in. The only thing that I had to as a test base was my Swamp Rat/ Wally Hays collaberation, it's a tripple tempered 52100 steell, and I only used it to compare edge retention ( I paid real money for it, didn't want to wreck it). On 3/4" manilla rope (a bit overkill) the Swamp Rat did 2 cuts where as mine did almost three. I tnen resharpend both, the edge coming back to mine with far less effort then on the swamp rat.

I then grabed a 2x4 and got about half way through (qite a chore with a 9" knife) before I got board with that game. By that time it was redy for another touch up, but still it was not quite yet dull. At this point I went ahead with some plunge cuts. At first I just stabed it as far into the wood as I could, and then poped it out. After a number of these I again got board.

Before I go on, let me mention that I had every intention of not breaking the knife when I started, but sometimes just don't know when to stop. So the next thing I knew I had a hammer in my hand and I was driveing the tip into the wood. The first time I set it in about 1/2' before popping it out. There still was no visable sighn of damage, so I proceded to drive it in about 3/4" or 7/8". When I was unable to pop it by hand I set it on the floor, and while standing on the bord, I pused doun on the blade with my other foot. It was at this point that I realized that I was getting carried away. Well I was convinced when I looked at the tip, or the spot where the tip should have been. About 1/8" had been broken off.

After that I set it into the vise and bent it just past 45 deg, first one way, then the other. It wan't utill I went the secound direction that the bend stuck. When I took it out of the vise I couldn't resist makeing a couple of cuts in the vise, and this prduced verry little in the way of chipping.

Conclusion: I think that it past the strenth test just fine. The grain structure looked good where it had broken off, though it could have been a bit finer. I do, however, think that edge retention should have been better. Though It did do a little better then the 52100, it seems that O-1 should have done far better, and the next blade will be treated to a triple temper.