Burnt edges - Elmax

A number of people have reported fairly low performance in Elmax :





JDavis took some heat for this one, and yes in general you want to slow down in conclusions before you categorize a steel. However it didn't take long before a number of people reported the same issues :





However when they started sharpening them they started to get better results after repeated sharpening. prometheus19799791 takes about it fairly extensively in the above video.

Now this sounds like over heated edges which was the ongoing hypothesis for some time, moved out of the hypothesis stage fairly clearly by another video by JDavis :






Stainless steel resists scaling very strong (for the same reason it resists rusting as both are oxidization). If they are burning the edges so badly the bevel is discoloring then the very apex itself has long since been over heated and likely micro-cracked if they are water quenching it.

The curious question is why Elmax, is this steel so difficult to grind compared to 154CM and S30V?



Edited 1 time(s). Last edit at 04/22/2013 03:36PM by CliffStamp.

I had that knife (Kershaw Speedform) showing on the video. The knife came with a very obtuse factory edge angle so its cutting performance left a lot to be desired. So, I reprofiled the edge with sand paper (maybe 15 to 17 DPS). I was able to realize that this Elmax steel seems to be more wear resistant than S30V as it was hardr to grind. However, when I started testing the reprofiled knife on cardboard, its performance did not impress me. As a matter of fact, I felt a Spyderco Sage had beter edge holding. I was expecting more from Elmax.

In general I would recommend not paying much attention to early performance. Carry the knife for awhile, us it for the heavier work, see how it does. After a few sharpening sessions, not stropping, actual sharpening - then see how it performs.

Its obviously getting better because elmax work hardens the more you sharpen it. Burnt edges indeed

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me2
Its obviously getting better because elmax work hardens the more you sharpen it. Burnt edges indeed

Ok, ok,
I knew that it would be very hard to resist. Therefore a link, especially for you:

[www.foundryworld.com]

(The include the link thing is disappeared from my screen)

Ok, read the text and enjoy yourself. I will come up with a new way to work harden Manganese steel by explosion treatment. Normally they use trains for it. Do not worry though. It will all fall into place.

BR.
J.

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CliffStamp
In general I would recommend not paying much attention to early performance. Carry the knife for awhile, us it for the heavier work, see how it does. After a few sharpening sessions, not stropping, actual sharpening - then see how it performs.

When I changed the edge profile I did it with 180 grit sand paper and it took me a while. I then refined the edge with 220, 320 and 600 grit paper. I removed a lot of metal. The new edge was completely different from the factory edge; the geometry was changed noticeably. Therefore, I doubt there was a burnt edge left.

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CliffStamp

The curious question is why Elmax, is this steel so difficult to grind compared to 154CM and S30V?

Does it generate more heat through friction with the belt?

Elmax has a lower grindability than S30v (and 154CM) but I can't see that being significant. Now if they try to grind Elmax as they are grinding the Sandvik steels then they could have a problem. I still strongly suspect this is what caused the initial heavy rush of problems with S30V.

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CliffStamp
Elmax has a lower grindability than S30v (and 154CM) but I can't see that being significant. Now if they try to grind Elmax as they are grinding the Sandvik steels then they could have a problem. I still strongly suspect this is what caused the initial heavy rush of problems with S30V.

I assume you are talking about how they are sharpened at the factory. How should the high carbide steels be sharpened as opossed to the Sandvik steels?

If a steel has low grindability then there is a higher chance of greater heat being generated when power sharpening because they demand :

-fresher abrasives
-higher quality abrasives

If you took a guy who was used to grinding the edges on 14C28N for example, he could likely do that with a cheap and worn belt, but the same belt will not cut as aggressively on Elmax and thus generate higher heat.

If they are going to power sharpen then :

-buy top quality belts designed to cut high carbide steels
-change them often
-do not let them get loaded
-use light passes
-ideally use a coolant
-do not water quench the blades when hot

If they are burning the steels so bad they are discoloring then they have to be leaning very hard into old belts.

Thanks Cliff. This makes a lot of sense and it makes me wonder: In order to reduce costs as much as possible, how many makers keep using worn belts to the point they won´t perform causing burnt edges? (which translates in poor performance and low durability).

Of course, this is detrimental to the end users. The thing is, the issue goes beyond poor performance; unsatisfied customers will not want to buy from the manufacturer again and the maker will experience a decrease in sales, and thus, the lost revenue from lost sales will be greater than the costs they save by spending less in grinding belts.

I also wonder how many (and which) makers have a "protocol" or internal policy regarding the use of new/worn belts in order to avoid this problem.

The amusing thing is that belts are cheap, labor is expensive and OH&S claims are very expensive, and complaints from customers are very expensive. They are not saving money and worn belts can be used for other things like shaping handles, contouring and chamfering and initial cuts on sharp edges. It is just poor practice.

I will use belts to the bitter bitter end... unless I have very little time to get a project done.

My belts are organized with the freshest ones in the middle, the ones I use when grinding an order, and worn ones on the outside for removing scale, grinding random stuff, profiling when not in a hurry etc.

As the edges get thinner the belts need to get fresher. Switching from wheel to platen the belts need to get fresher. As I slow the grinder down I can get a little more life out of the belts.

At full speed my grinder will destroy some belts in seconds, not just cheap ones either. Seriously, three or four passes and then zero cutting. I save those belts for my "belt stirred D2" edges

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wnease
I will use belts to the bitter bitter end... unless I have very little time to get a project done.

My belts are organized with the freshest ones in the middle, the ones I use when grinding an order, and worn ones on the outside for removing scale, grinding random stuff, profiling when not in a hurry etc.

As the edges get thinner the belts need to get fresher. Switching from wheel to platen the belts need to get fresher. As I slow the grinder down I can get a little more life out of the belts.

At full speed my grinder will destroy some belts in seconds, not just cheap ones either. Seriously, three or four passes and then zero cutting. I save those belts for my "belt stirred D2" edges

My belts go in the bin at about 50% life most of the time. I just like fresh belts and fast cutting. I hardly ever do anything but hard steel grinding. the 50% are great for when I'm grinding annealed steel, or o1, 1095 type steel, but most of the time I just trash them .

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It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen

If I know I'm making a couple bucks on a blade, sure , fresh belts, but if not, I can't always justify $12 per belt on another personal project

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wnease
If I know I'm making a couple bucks on a blade, sure , fresh belts, but if not, I can't always justify $12 per belt on another personal project

I can understand that.. when I'm binning belts, its because the items are being paid for, and I just build it into the cost at a lower profit margin then I could get.

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It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen