Revealing Kiln Test.

stevomiller said:
Properly functioning equipment, known composition steel, industry proven HT protocol, industry tests and standards - rockwell, charpy, % martensite, grain size, etc. Sample proven in application. Then you have your benchmark.
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Thank you.... I was running out of ways to say it.... short but sweet saves the day.

I took your question seriously Avigil... if my answer seemed to be making light of it, I apologize.... that was not my intent.
 
stevomiller said:
Properly functioning equipment, known composition steel, industry proven HT protocol, industry tests and standards - rockwell, charpy, % martensite, grain size, etc. Sample proven in application. Then you have your benchmark.
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That is absolutely correct and as we have seen the variance in HT equipment and its calibration can be problematic. sometimes the steel we get might have variances from different suppliers. Even some of the data sheets vary on temperatures for Heat Treating.

Professional heat treating firms like Paul Bos might be the best bet for actually getting "full potential" from heat treatment. The equipment is far superior to garage heat treating ovens and they work to an industrial standard and have far more experience than any single knifemaker.
 
Adam... I am not saying that you can't make a good knife using O1, a coal forge and canola. I'm just saying that it is wrong to automatically claim it's superior properties if you do not have the means to adhere to the industry HT schedule or the data to formulate your own.

I just read your last post and I see we are headed to the same place on adjacent paths. I agree... we have to know that our equipment is working properly and that we follow the outlined HT temperatures to achieve the projected result. There is a little faith needed as to whether or not the steel composition is what the supplier says it is. Bos heat treating is good at what they do, but properly calibrated garage kilns and quench practices can be quite comparable.
 
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the coils in an electric oven are on/off- they fire up to max and as the oven reaches temp they cycle to get the desired temp inside the oven. Putting blades in during the ramp up can overshoot the temp, untill the oven equalizes.
 
Rick Marchand said:
Adam... I am not saying that you can't make a good knife using O1 and a coal forge. I'm just saying that it is wrong to automatically claim it's superior properties if you do not have the means to adhere to the industry HT schedule or the data to formulate your own.
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Rick I think you ,think I have a problem with this discussion. I don't, I understand people are quick to defend what they do. Thats not what I am doing. I just want to know if there is a "full potential" for a knife then we should be able to have data of what that actually consist of in a knife.

I will send my knives out for HT I will do some on my own . I am not emotionally tied to any method this is fun for time for me.

We have had many discussions on quenchants and people are adamant that engineered quenchants are best. The same can be said for using the best heat treating facility available. If the goal is reaching full potential then the best, most consistent and controlled HT method would be called for and professional heat treatment will get you closer to that since their equipment is calibrated and meets industry standards.

I think most knifemakers make good and great blades but how many actually have reached "full potential" probably are less then claimed.
 
Oven coils don't have to be fully ON or OFF. Use of all the controllers features (% ,power etc) and a TRIAC will clip the A/C wave and change the phase angle. Think of it as using a logic contolled dimmer vs on/off switch. This + ramp rates, muffles, etc will help insure proper heating.

Additionally, if u use a smart ramp/soak controller make sure it has multiple routines. Otherwise it will lose its tuning when you change reciepe for different steels.
 
stevomiller said:
Oven coils don't have to be fully ON or OFF. Use of all the controllers features (% ,power etc) and a TRIAC will clip the A/C wave and change the phase angle. Think of it as using a logic contolled dimmer vs on/off switch. This + ramp rates, muffles, etc will help insure proper heating.

Additionally, if u use a smart ramp/soak controller make sure it has multiple routines. Otherwise it will lose its tuning when you change reciepe for different steels.
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I was speaking of a max ramp up to temp. Yes there are ways to midigate overshooting. I'm repeating what I was told by the company (evenheat) that I bought mine from.
 
I don't know how smart the Orton controller is for my kiln but it holds 9 programs with 9 steps to each. I don't think it has the "dimmer switch" thingy-ma-jiggy.
Rick
 
Do any of the heat treating ovens commonly used by hobby and individual knife makers (Evenheat, Paragon, Sugar Creek) have the capability to clip/change the AC in order to smartly control the coil temp? Most that I am aware of are on/off systems, with the more complex types of controllers being cordoned into the realm of larger industry.

--nathan
 
Rick, is it an Omron controller on your unit (you typed Orton)? If so I bet it does the "dimmer thingy" ;-). What model is it? The problem is that there isn't anything for it to control this way (well, not by clipping the wave ~ you can set it for maximum percent time on). You would need to buy a TRIAC (phase angle firing thyristor) with a heat sink to replace the SSR, with the amperage rating to meet your unit's demand. As far as any home use/small shop units having it I doubt it. It would add perhaps $300 to the unit cost.
 
JBS TOOLMAKER said:
So says the label.:rolleyes:
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I am reading your reply as seriously calling into question the accuracy of tempilstiks. What is your concern? (Or am I misreading your post?)

According to the manufacturer, tempilsticks are NIST traceable and certified for use in nuclear use, and they claim to meet multiple industry standards. I'm guessing they'd be pretty interested if evidence exists that they do not work correctly.
 
I had a few stored in an unheated outdoor shop.

They crumbled, disintegrated, dissolved the paint in the tool chest drawer and started to rust everything in the drawer.

Watch how you store them.
 
Most everybody here knows I have a special penchant for D2. Please allow me to relay some hard earned experience pursuing "full potential" as focused on that one particular alloy.

First, it is folly to think that having a perfectly calibrated oven and following "industry standard practice" or sending out to a reputable heat treat provider will necessarily extract the full potential from the steel. Without going into another of my extremely long dissertations about retained austenite, free chromium, grain size, carbon lean martensite, cryo and carbide fraction (and blah blah blah), allow me to summarize, I have learned this: Commercial practice is generally not about fine edged cutting implements, and commercial heat treaters are largely focused on hitting Rockwell numbers without warping or cracking your work. I think we all know that, at least for D2, when it comes to knives the "standard" leaves a lot on the table and most of us are taking pains to grab the low hanging fruit that has become well recognized and straight forward to achieve. At least around here we are. But this begs the question, how does one determine if they're reaching the full potential of a steel if following the industry standard or sending out to a reputable heat treater isn't necessarily the gold standard?

I have my own thoughts about this, but I'd like to hear others?
 
Tait said:
I am reading your reply as seriously calling into question the accuracy of tempilstiks. What is your concern? (Or am I misreading your post?)

According to the manufacturer, tempilsticks are NIST traceable and certified for use in nuclear use, and they claim to meet multiple industry standards. I'm guessing they'd be pretty interested if evidence exists that they do not work correctly.
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I was just being sarcastic....but I will say that the company that does our yearly ISO tool calibration does not reccomend them. They prefer the test that I described in an earlier post. The facts are that no test is more conclusive than a Rockwell test after quench. If for example an air quenched tool steel should be in the 63-66 range at quench, and your soak time, wrap, etc. was correct and your (calibrated) Rockwell tester says 65 then your oven temps are correct. If it says Rc 48 at quench then your elements or thermocouple is probably junk. There is another shop here close to my home that specializes in gear production some up to 80" in diameter. They have an awesome heat treat shop, we send our larger work to them. I'm gonna go talk to him this week and find out what his testing procedure is, there ovens have to run tight because they do a lot of work for the airline industry.
 
Nathan,
It should be the full potential for the given purpose. D-2 can be drawn many differant ways to reach the full potential for the purpose double draw @500, triple @ 900, cryo, no cryo. I think people lose sight of what the tool was supoosed to do. Skin deer or chop down oak trees ? Heat treat two knives the same and they won't do one of those task very well.
On another note. Even when I send out my stainless for heat treat, I still Rockwell test it when it comes back. I can't rightly say my product is 59 Rc. if I don't see it myself.
 
JBS TOOLMAKER said:
If for example an air quenched tool steel should be in the 63-66 range at quench, and your soak time, wrap, etc. was correct and your (calibrated) Rockwell tester says 65 then your oven temps are correct.
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Got it. Thanks.

That's actually really good to hear - I am hitting within 1 point of target HRC, and I thought that meant my process was good. The fact that somebody who takes this stuff really seriously also believes it tells me I'm probably not far off.

It's so easy to *think* I'm right, and so hard to be able to demonstrate it convincingly to others...
 
JBS TOOLMAKER said:
Nathan,

D-2 can be drawn many differant ways to reach the full potential for the purpose double draw @500, triple @ 900, cryo, no cryo. I think people lose sight of what the tool was supoosed to do. Skin deer or chop down oak trees ? Heat treat two knives the same and they won't do one of those task very well.
On another note. Even when I send out my stainless for heat treat, I still Rockwell test it when it comes back. I can't rightly say my product is 59 Rc. if I don't see it myself.
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Yes, but it is easy to make a knife in D2 using "standard practices" that does both of those tasks poorly. And the rockwell numbers can be almost meaningless, so they are no guide.

For example, you can have two D2 knives with the same geometry that came out of the same bar of steel that were heat treated two slightly different ways (change the timing of a couple of steps) that both have the same rockwell hardness, and one can do a variety of tasks ranging from fine cutting to rough use well, and the other nearly identical twin does poorly at these same tasks.

My point here is, without actually testing the work, you wouldn't know if the process was working. And if you'd never compared the results with other known good work, you might mistakenly believe you were getting the "full potential" out of the steel by following the industry standard or using a reputable heat treater.

I have test blades like this here, and I can send them to you if you'd like to see what I'm talking about.
 
Nathan the Machinist said:
.....how does one determine if they're reaching the full potential of a steel if following the industry standard or sending out to a reputable heat treater isn't necessarily the gold standard?

I have my own thoughts about this, but I'd like to hear others?
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That is what I would really like to know.

Ed Fowler was taken to task on this forum for making claims on the methods he uses. But when other make the claim of "Full Potential" their objective evidence is lacking and mainly relies on the "I followed the directions so it must be at full potential".
 
Fascinating conversation gentlemen, thank you. I've often been told to put blades in cold and let them heat up with the kiln, but I think I understand how that could be a problem, now. I'm not qualified to ask the complex questions, so I'll ask a simple (but multi-part) one:
A) after allowing the kiln itself to reach temp and stabilize, how long does it take for a room-temperature blade to reach the desired austenizing temp? If I understand this right, it's important to let the whole piece come up to temp, then time the "soak", yes? (FWIW I'm talking about deep-hardening, moderate-to-high-alloy steels, so I'm presuming this is fairly important)
B) Would preheating the steel to, say, 400F in a separate oven while the kiln ramps up and stabilizes help, or just be a waste of electricity?
C) Again, assuming we're dealing with a kiln that's as accurate and stable as we can get it, what effect does putting in 6 blades rather than 1 at a time have? Does the extra mass help keep things even, or would I get measurably different results on the blades closest to the walls/elements, compared to the one in the center of the kiln?

I have a 14" 110V Paragon, if that makes a difference.
 
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