CPM-M4 at low angles. My experience recently.

marthinus

marthinus

Joined
Dec 10, 2006
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5,952
I have been decreasing the edge angle on my Gayle Bradley using the shoulders as a guide.

Finally finished with it and the edge is around 5 Degrees Per Side (DPS). Finished it up on a Spyderco UF stone.

The edge was shaving sharp in both directions and felt very crisp to the touch.

Mandatory glamour shots.

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I went ahead and did some woodwork. This piece has been dried out for some time so it was nice and hard.

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Results where....well interesting to say the least. Significant edge deformation in terms of chipping.

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Sharpened to 10-12 DPS.

[video=youtube;qzzzrcaEQE4]http://www.youtube.com/watch?v=qzzzrcaEQE4[/video]

There remained a small chip:

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Rerun of the test on the same piece of wood, focusing on an area with a small knot. Did not experience the same deformation.

GayleBradleySamplesaftermacrobevel_zpsa09b461a.jpg


AfterMacrobevel2_zps28b867be.jpg.html


What can I conclude:

Nothing much, this is just an fyi for those that might have wondered how CPM-M4 might perform at this low angle.
 
What did you do for the second sharpening - add a microbevel? It's good to experiment. Thanks for sharing.
 
AF said:
It's good to experiment. Thanks for sharing.
Click to expand...


I agree.


You're almost there, setting that edge a little thicker will give the performance you seek with the support it needs.


What your doing is the best way to tailor an edge to meet your requirements.





Big Mike
 
I don't take my knives, regardless of the steel, below 15. From my experience the increase in cutting ability doesn't outweigh the decrease in edge life and risk of damage. Nice pictures to go along with the experience though! That low of an angle should be quick to touch up by adding a back bevel if needed
 
Dang , that knife looks great, and I wasn't expecting that, I've got my GB at 20 degrees inclusive and it has peformed very very well, I guess we know that if we go 10 degrees inclusive it's a little too much :D Can't knock ya for trying though:thumbup:
 
Why not stay with 10 degrees inclusive then make a microbevel at 20 degrees inclusive?
 
Glad so many of you enjoyed my little trial and error.

Big Mike said:
I agree.


You're almost there, setting that edge a little thicker will give the performance you seek with the support it needs.


What your doing is the best way to tailor an edge to meet your requirements.





Big Mike
Click to expand...

Catering an edge to meet individual needs is something many over look. Through years of trial and error I know my personal preferences with regards to angle of a backbevel, microbevel, final finish of the edge for push cutting or aggressive slicing etc.
 
That chipping looks pretty bad. Thanks for letting me know not to try sharpening to that steep of an angle with that steel.
 
Good to know--great knife too.

Off topic--why the fencing and razor wire? It looks like you are in a compound of some sort.

DJK
 
Looking at the dusting on the edge and the scratches there was definately some sand or rocky material in that wood (oh, and the knots), not surprised it chipped. I'm guessing with cleaner material M4 would take those low angles better.
 
expwmbat said:
Good to know--great knife too.

Off topic--why the fencing and razor wire? It looks like you are in a compound of some sort.

DJK
Click to expand...

No compound :) just part of work. Health and Safety etc. Will post pictures of the area for you when I am not on the phone.

You can google 'Busse Basic 4 some use' user name is mwvanwyk and you can see towards the end of the video I posted some pictures of where I do some work.
 
yoda4561 said:
Looking at the dusting on the edge and the scratches there was definately some sand or rocky material in that wood (oh, and the knots), not surprised it chipped. I'm guessing with cleaner material M4 would take those low angles better.
Click to expand...

Unfortunately cleanliness of material being cut can't be controlled in my work. If the edge could not handle that wood it would not hold up to the work it would see day to day.
 
Not meaning to hijack..for those who care my para 2, cts-xhp, has been brought down to an angle less then factory (sorry don't know exact angle) is experiencing minor chipping when pushed to harder use (minor landscaping tasks) it doesn't bother me though...talk about a toothy edge :rolleyes:
 
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