looking for straw

R

rlinger

Joined
Mar 29, 2002
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I just tempered a O-1 blade at 375 F. for 36 min. I kept looking for the straw color by opening the oven door about every five minutes after the first fifteen min. I figured if I checked any sooner the oven temp would not stay up high enough, so I chose five min. intervals. After 36 min. I got to worrying about keeping it in too long.

Upon removing the O-1 it was (I thought) a purple color with a little bit of goldish mixed in, especially closer to the spline. Now that it is room temp. it looks like a cooper color (like staw and purple blended???). The edge, however, is a real nice looking blue or better yet a purplish blue.

Did I pass the straw up or did I not temper long enough???

Thanks, Please.
 
Sorry they've changed that site since I was there last, once you get there punch on "Bob Engnath's page" lots of good info.

Bill
 
I would say that purple is way above 375deg.,F. You might want to get an oven thermometer, the oven control is usually off, sometimes surprisingly so. :eek:
 
I temper my 01 at 375 for 1 hour, take it out and let it cool, then another hour at 375. It turns out a nice golden straw color. If you got your color to purple, your temper was way too hot, and you will need to go back and harden the blade again. Also, I wouldn't open the oven door until it is finished. It may be a good idea to take some scrap pieces of 01 and temper them to find out the best setting for your oven.

-chris
 
Rlinger - I know you've been following my thread on Testing O1 - I'm going to put this on there, too.

.... I salvaged three of my 1/8" test blades, reground them and heat treated them. I tempered all at 375 for one hour in my oven . At Nick's suggestion. I got an oven thermometer and also lowered my temp. (from 410). Anyway, I got a very light straw color - the color was just coming up. At 420 I got a noticably darker straw color.

It put an edge on it and it cuts well and seems to flex and return with the brass rod test. (I put a lot of light on there so I could seeit) I put the other two blades in the freezer and I am going to temper them again at 375 tomorrow -see what (if any) difference.

I don't know the answers yet, but after looking at the way my results are going and reading other threads and replies its looking like 350-400 is the best range, check your temp, temper an hour at a time and maybe more than once. Everyone seems to get a method that works best for them.

Bob
 
and of course to Southriv,

I am conducting a simple test of my oven. For the last couple hours I have been trying to get a soup bowl half full of water to boil. First, for one hour I let it cook at 200 F. (all this is according to the front dial as I have no thermometer for these purposes yet). No boil at 200 F. Then I set the dial half way between 200 and 225. Let cook for 1/2 hour. No boil. Now, as I write, it is set to 225. We'll see.

My experience with this oven is that I need to set my dial to indicate about 25 degrees higher than the recipe calls for. I occasionally make biscuits, pizza and apple pies for my lady - something I learned after the divorce. Experience has taught me to go 25 degrees high on this (piece of junk) oven.

Bets me. I'll keep testing until I find the dial indication that boils water. News at eleven. I will report back.

I did temper again at 350 F. for 30 min. I then ground all scale off, put a dull edge on and cut about 60 ft. of cardboard. The edge felt like about 85 percent after that. With a ten power jewlers loop I could see no chiping and the edge looked consistent about its length.

Later
 
Okay, to 350 F. I went; no bubbles. Closed the door and let cook a little longer. Open door, pull out rack, put meat thermometer in water. Climbs to 190 degrees and falls. Okay, maybe got facked out. Push rack back into oven, close door, set oven to 350 again and let set for 30 - 35 minutes. Open door - no bubbles. Pull rack - no bubbles. Themometer climbs to 200 F. and falls.

Three things: get new cooking oven (there will be no fly-in fishing trip to Canada this year); get good toaster oven (drill hole); get a candy thermometer for good toaster oven. Don't forget to order the Even-Heat kiln next week.

If I wasn't hooked I'd just go back to customizing rifles and be done with it. I so hate love this stuff.
 
I got an oven thermometer and tested the temp at the 375 F. setting. Its only high by 125 F. My 375 degree temper was a 500 degree temper.

Did the HT again and saw the ghost shadows this time, yea. Tempered at 375 for 60 min. (a real 375), put in freezer (0 F.) for 12 hours, re-tempered at 350 for 45 min.

I got the STRAW now! Beautifull!

Thanks fellows, you were right (of course).
 
Rlinger - excellent! ...A modest investment, a lot of tinkering and you finally got what you wanted -its looks like you are right in the ball park - good work!

Bob
 
Thanks. Oh, I got more to say.

Guess what, I know now why I never bought a oven therm. before. It cost me all of 3 bucks! I also got a digital meat therm. for 12 bucks. I'm using it for my quenching oil. While I was at it I got a toaster oven for the tempering. Got the biggest one they had - 14 inch wide cavity. Has a big clear glass door so I can find the straw and see my temp. Ordering the Even-Heat kiln tomorrow.

I'm going to be a heat treat'n fool. A real fire breather, I'll be.

Later
 
Looks like you've got things taken care of. Was just going to tell you that I just started doing my own HT on 01 and was pretty happy with setting the oven 350 and tempering for an hour, letting it sit over night and tempering again. All ovens are different though, hadn't thought of that.
Judging from the way my oil stones will cut the steel after tempering, what I read in an old copy of the American machinist hand book, and the temper chart that came with the steel, I'm ending up between RC60 and RC62. Takes a super fine edge. Haven't gotten to do any real extensive testing yet, but they seem reasonably tough for the small knives I'm doing. Mainly folders in the 2"-3" blade range.

Sounds like your going for closer to RC59-60. How does that perform? Have you gotten to try it out much yet?
 
I'm shooting for Rc 61 - 62. I think I may have come close the last time, if my temps were correct. I placed the oven thermometer at the mid point of the blade, looked for straw at a reading of 350 F.. Took about 60 min. When I heat treated I looked for the ghost shadows to appear. When they dissapeared from the blade I immediatly quenched in 137 degree F. vegetable oil.

I'm grinding a 4 inch skinner now. I think I'll shoot for Rc 58 -59 on it. Its longer and wider and will only be used for skinning deer.
 
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