Blade testing results summary and lessons learnt

[sebaldus]

Great Video! You have a talent for teaching. I found your testing very cool, it's nice to see a knifemaker put so much effort into the quality of future blades. Don't be swayed by naysayers. Due diligence is always a good thing.

 

[aarongough]

Great Video! You have a talent for teaching. I found your testing very cool, it's nice to see a knifemaker put so much effort into the quality of future blades. Don't be swayed by naysayers. Due diligence is always a good thing.

Thanks mate!

 

[lilguy]

I think the test was awesome, as a new knife maker I have been struggling to decide which steel to use. Mainly because I've struggled to find comparisons between the steels. I am able to find comparisons between all the tool steels and between 4 xx steels and 10xx steels bit none comparing tool to 10xx or cpm to tool etc. Get test and awesome info for a dummy like me..

 

[aarongough]

Glad you found it helpful!

 

[aarongough]

Just in case anybody was having trouble finding the full results in the other thread:

Compiled overall test results:

Given that the edge retention testing was not terribly significant I'm focusing on the toughness aspects of the testing. Below I have compiled a list of the results from both sets of tests.

I compiled the results using the blade numbers so I wouldn't remember which blade was which, then replaced the blade numbers with proper descriptions.

Break test:

[FONT=Courier New]
Worst:
Blade 9 - A2 Ver2 (62.5HRC) - 10º
Blade 1 - CPM154 Ver1 (59.6 HRC) - 15º
Blade 6 - 440C Ver1 (59.1 HRC) - 25º
Blade 3 - O1 forge  (55-60HRC) - 85º (bent strangely, plastic failure)
Blade 4 - O1 Ver1 (60.6 HRC) - 30º
Blade 11 - A2 Ver2 (60.5HRC) - 35º
Blade 7 - CPM154 Ver2 (62HRC) - 42º
Blade 8 - O1 Ver2 (59.7HRC) - 42º
Blade 12 - 440C Ver2 (59.5HRC) - 42º
Blade 2 - A2 Ver1 (59.5 HRC) - 55º
Blade 5 - CPM3V Ver1 (61.1 HRC) - 60º
Blade 10 - CPM3V Ver2 (60.5HRC) - 90º (Wow!!!)
Best:
[/FONT]

Tip strength test:

[FONT=Courier New]
Fail:
Blade 9 - A2 Ver2 (62.5HRC)
Blade 7 - CPM154 Ver2 (62HRC)
Blade 3 - O1 forge  (55-60HRC)
Blade 4 - O1 Ver1 (60.6 HRC)
Blade 6 - 440C Ver1 (59.1 HRC)

Pass:
Blade 2 - A2 Ver1 (59.5 HRC)
Blade 1 - CPM154 Ver1 (59.6 HRC)
Blade 8 - O1 Ver2 (59.7HRC)
Blade 10 - CPM3V Ver2 (60.5HRC)
Blade 11 - A2 Ver2 (60.5HRC)
Blade 12 - 440C Ver2 (59.5HRC)
Blade 5 - CPM3V Ver1 (61.1 HRC)
[/FONT]

Impact testing:

[FONT=Courier New]
Worst:
Blade 12 - 440C Ver2 (59.5HRC) - large 7/16" wide chip taken out of the blade
Blade 4 - O1 Ver1 (60.6 HRC) - large section of edge chipped out
Blade 9 - A2 Ver2 (62.5HRC) - smallish chip at first (about 1/32" across), but the blade spontaneously cracked several minutes after the blow. The crack extended 3/8" up the bevel
Blade 6 - 440C Ver1 (59.1 HRC) - decent chips and some bent sections
Blade 11 - A2 Ver2 (60.5HRC) - decent sized chip 3/16" across
Blade 5 - CPM3V Ver1 (61.1 HRC) - section of edge bent and deformed
Blade 8 - O1 Ver2 (59.7HRC) - small bent/torn section of edge 1/16" long
Blade 3 - O1 forge  (55-60HRC) - some small amounts of chipping and rolling
Blade 1 - CPM154 Ver1 (59.6 HRC) - very little damage, some slight chipping
Blade 10 - CPM3V Ver2 (60.5HRC) - small chipped/rolled section of edge 1/16" across
Blade 2 - A2 Ver1 (59.5 HRC) - almost no damage, slight rolled section of edge
Blade 7 - CPM154 Ver2 (62HRC) - small section of edge rolled, no chipping
Best:
[/FONT]

The only real failure in edge-retention was 440C Ver1, which held an edge noticeably worse that the others. Every other blade is likely pretty close overall in retaining an edge.

Overall ranking:

Point were assigned to each blade according to how it placed overall in each test. 1st was 12 points. 12th is 1 point. Not breaking in the tip test is 6 points.

[FONT=Courier New]
Points:
Blade 1 : 2 + 6 + 9 = 17
Blade 2 : 10 + 11 + 6 = 27
Blade 3 : 4 + 0 + 8 = 12
Blade 4 : 5 + 0 + 2 = 7
Blade 5 : 11 + 6 + 6 = 23
Blade 6 : 3 + 0 + 4 = 7
Blade 7 : 7 + 0 + 12 = 19
Blade 8 : 8 + 6 + 7 = 21
Blade 9 : 1 + 0 + 3 = 4
Blade 10 : 12 + 6 + 10 = 28
Blade 11 : 6 + 6 + 5 = 17
Blade 12 : 9 + 6 + 1 = 16
[/FONT]

Best:
Blade 10 - CPM3V Ver2 (60.5HRC)
Blade 2 - A2 Ver1 (59.5 HRC)
Blade 5 - CPM3V Ver1 (61.1 HRC)
Blade 8 - O1 Ver2 (59.7HRC)
Blade 7 - CPM154 Ver2 (62HRC)
Blade 1 - CPM154 Ver1 (59.6 HRC)
Blade 11 - A2 Ver2 (60.5HRC)
Blade 12 - 440C Ver2 (59.5HRC)
Blade 3 - O1 forge (55-60HRC)
Blade 4 - O1 Ver1 (60.6 HRC)
Blade 6 - 440C Ver1 (59.1 HRC)
Blade 9 - A2 Ver2 (62.5HRC)
Worst:

 

[Kloepper Knife Works]

Excellent work. Anyone who thinks your test was a waste isn't very interested in making the best knives they can. I'm not saying people should change the steels they're using, but testing is how we improve our understanding of our steels, knives, and processes. It was the biggest lesson I took away from my time talking to Ed Fowler.

Side note to OP, I've read many of your posts and appreciate the way you compose yourself and thoughts. I think you are someone trying to make the best product you can, and are working hard to take all the correct steps to get there. As I work on my second run of knives right now, I'm planning/doing many of the same things you are. Good luck on your future, I won't be surprised to find out that you make a great name for yourself.

 

[aarongough]

So I actually have an update to the testing! I was talking to Des Horn at the Canadian Knifemakers Guild Show the other day, and he was saying how much he liked RWL34 and recommended that I try it or something similar like CPM154.

That made want want to go back and have a look at the results of the testing that I did all those months ago. When I was looking I noticed something... The steel that actually fared the best in the impact toughness test was CPM154.

That got me thinking. If that steel did so well in impact toughness why was it behind the other steels in the final results? The reason was because it 'failed' the tip strength test. If it had passed the tip strength test then it would have been 3rd overall in points rather than 5th, with the difference between the top 3 being nothing other than minor.

Luckily, after I completed the testing 'way back when' I decided I would label and keep all the broken parts in case I had a future use for them. So I went and dug them all out to see what the tip thickness was like on the CPM154 sample compared to the other blades, something I probably should have looked at in the past!

Here's the results:

Turns out that CPM154 likely failed the tip strength test simply because the tip of that test blade was a fair bit thinner than the other test blades! (27% thinner)

I grabbed a couple of the test blades and re-did parts of the impact testing, and it's really not a fluke. I wailed on the edge of the 2 CPM154 test blades with my trusty 'testing crowbar' and they held up really well. Every bit as well as the CPM3V test blade and the A2 test blade.

It seems I might have discounted CPM154 without good reason, so I'll be making a few test blades in it over the next few weeks to see how they hold up to some further testing.

Just wanted to make sure that people got the update!
-A

 

[aarongough]

Excellent work. Anyone who thinks your test was a waste isn't very interested in making the best knives they can. I'm not saying people should change the steels they're using, but testing is how we improve our understanding of our steels, knives, and processes. It was the biggest lesson I took away from my time talking to Ed Fowler.

Side note to OP, I've read many of your posts and appreciate the way you compose yourself and thoughts. I think you are someone trying to make the best product you can, and are working hard to take all the correct steps to get there. As I work on my second run of knives right now, I'm planning/doing many of the same things you are. Good luck on your future, I won't be surprised to find out that you make a great name for yourself.

Thanks for the kind words mate!

 

[ChristoDart]

Excellent work. Anyone who thinks your test was a waste isn't very interested in making the best knives they can. I'm not saying people should change the steels they're using, but testing is how we improve our understanding of our steels, knives, and processes. It was the biggest lesson I took away from my time talking to Ed Fowler.

Side note to OP, I've read many of your posts and appreciate the way you compose yourself and thoughts. I think you are someone trying to make the best product you can, and are working hard to take all the correct steps to get there. As I work on my second run of knives right now, I'm planning/doing many of the same things you are. Good luck on your future, I won't be surprised to find out that you make a great name for yourself.

:thumbup:

 

[Phil Wilson]

Aaron, A lot of information here and appreciate the effort. One point that is missed,unless I missed it, is that one thing learned is how your setup, furnace, thermocouples, quench methods, subzero, hardness tester calibration, all work together to give you the result you want. Yes the data sheets give you a place to start but a lot of it is laboratory results on different thickness and sections than a what you get with a knife blade. Only way to figure it out is to test and keep good records like you have done here. You basically have calibrated your set up for several steels. May not be the same for other maker's set up.

I like CPM 154 for fillet blades and found that with my setup I can get some plastic deformation in bending before breaking at 59 to 60 Rc with a flexible blade. Edge holding is still very good at that hardness. Better at 62 but trading off edge holding for ductility. Another point on the curve for you.

Yes edge holding testing is tough to define. I found you have to go to at least 5/8 rope and 3/4 inch gives quicker results otherwise you will be cutting for a long time. Phil

 

[gadgetguy9000]

Thanks for the replies Aaron. This knife making certainly is area where many different approaches are used to get results. I do believe "it's not what you use or how you get there, but how good the results are." Frank

Of course the end results are entirely dependent on the approach used to get there, hence the need for testing.

Thanks for all the hard work, Aaron.

 

[aarongough]

Aaron, A lot of information here and appreciate the effort. One point that is missed,unless I missed it, is that one thing learned is how your setup, furnace, thermocouples, quench methods, subzero, hardness tester calibration, all work together to give you the result you want. Yes the data sheets give you a place to start but a lot of it is laboratory results on different thickness and sections than a what you get with a knife blade. Only way to figure it out is to test and keep good records like you have done here. You basically have calibrated your set up for several steels. May not be the same for other maker's set up.

I like CPM 154 for fillet blades and found that with my setup I can get some plastic deformation in bending before breaking at 59 to 60 Rc with a flexible blade. Edge holding is still very good at that hardness. Better at 62 but trading off edge holding for ductility. Another point on the curve for you.

Yes edge holding testing is tough to define. I found you have to go to at least 5/8 rope and 3/4 inch gives quicker results otherwise you will be cutting for a long time. Phil

Thanks for the input Phil!
Yeah I agree that finding out how my whole system works together is definitely a valuable outcome from this.

Thanks for the reminder to try out thick rope for edge holding tests, someone else mentioned that a while back and I had forgotten about it. I will definitely have to try that out!

-A

 

[Evan Miner]

thanks Aaron for the info on this topicI've been reading along from the first post to this one it's been a wealth of knowledge and thank you again for all your hard work

 

[aarongough]

thanks Aaron for the info on this topicI've been reading along from the first post to this one it's been a wealth of knowledge and thank you again for all your hard work

Thanks for reading along! I'll be doing another round of testing soon, so hopefully some more interesting tests and results coming up.

 

[Arnestion]

wow really interesting topic)