Apexing the edge

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BruceMack

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May 20, 2015
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I have an inexpensive folder with a D2 steel blade. The factory bevel was > 15° so I reprofiled it to ~13-14° with the KME using the inclinometer on my phone. I finished with the 1500 grit diamond hone. Then, as usual, I added a 15° microbevel with the Sharpmaker followed by stropping. Though I have done this successfully with other knives, this blade still would catch on paper. The apex was shiny and I felt no nicks. Glancing light suggested some irregularity at the apex (? wire edge) which persisted after several resharpenings with the Sharpmaker rods finishing with almost no pressure as well as lightly running the blade edge perpendicular to a small block of wood.
Because I like the appearance and size of the knife I tried a light microbevel at 20°. The edge seemed sharper with no paper snags. I returned to the 15° setting and used enough passes (80 I think) with the brown rod to restore the original more acute microbevel. After stropping, the edge remains good with no snagging but still with a slightly visible ripple at the very apex.
I don't know what I did right and post this simply as a tribute to persistence in the presence of ignorance. At my level of inexpertise, I know this is just an anecdote but I ask other members of the forum for comments or possible explanations. The simplest would be that my reprofiling was incomplete, leaving an untouched apex, Sharpy notwithstanding, or leaving a roughness at the apex that could be removed only with a more obtuse angle.
Damn, I'm wordy. Apologies.
 
My 2 cents' worth, about D2:

I've always felt D2 is real needy in terms of apexing it cleanly & fully; I've always noticed this with D2. It demands more patience and effort when it gets 'close to' apexing, but not quite there. If it's just a bit shy, it'll be obvious in it's shortcomings in cutting tests, or shaving.

I've always preferred using a diamond hone to apex D2, as well as for refining the edge & polishing it. With ceramics or something less able to cut it as cleanly, it suffers more edge degradation if technique (angle control, pressure, etc) isn't very, very good. So, it's easy to take something away from it, performance-wise, if you're not very careful in apexing or in refining or polishing it, after it's apexed.

I think most/all of the above is due to the very large carbides in D2 (ingot version, not the powder-metal version called 'CPM-D2', which has much smaller carbides). D2's chromium carbides can be very large, up to ~ 50 microns sometimes; so it takes more work to delicately shape and refine them at the edge, than with many other steels.
 
Carbides in D2 are very large, will push out of line if worked thin with anything but diamonds in my experience. Have also had some luck stropping with fine silicone carbide and/or diamond grit, but for a 30° or less micro with a fine hone, really a diamond plate is best practices.
 
HeavyHanded said:
Carbides in D2 are very large, will push out of line if worked thin with anything but diamonds in my experience. Have also had some luck stropping with fine silicone carbide and/or diamond grit, but for a 30° or less micro with a fine hone, really a diamond plate is best practices.
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That's enlightening.
Thanks !
I never would have thought I should go diamonds for "Good O' " D2.
I haven't much experience with it. (just my Rat 1)
 
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Wowbagger said:
That's enlightening.
Thanks !
I never would have thought I should go diamonds for "Good 'O" D2.
I haven't much experience with it. (just my Rat 1)
Click to expand...
D2 can be heat treated poorly or even softer so it varies alot from brand to brand. From 54hrc to 63hrc. The Rat models iirc are around 58hrc give or take. So a bit soft but not on the low end of the range d2 specifications. I only have experience with 61hrc d2 and advertised as being used in cryo. Also have a brous that I'm not sure which kind of d2 nor its hrc. Neither of these could be sharpened with anything other than diamond and later found out SiC will work too. Ceramic was just not happening. D2 is suppose to be tough as balls to sharpen, it means you have a decent heat treatment imho lol. But it does have that reputation, so I've read.
 
HeavyHanded said:
Carbides in D2 are very large, will push out of line if worked thin with anything but diamonds in my experience. Have also had some luck stropping with fine silicone carbide and/or diamond grit, but for a 30° or less micro with a fine hone, really a diamond plate is best practices.
Click to expand...
In the past I have not been able to strop well with diamond paste or spray 1.0-0.5 microns. I don't seem to have those freehand skills. I can try again. Any experience with PSA aluminum oxide sheets? These are available from 2 woodworking sources at 0.3 or 1.0 microns. Silicon carbide seems limited to 5.0 microns. I could use the guided Sharpmaker rods with the paper applied in a thin strip and trailing strokes. Am I just chasing my tail?
 
My stropping preference for D2 is to use diamond compound (3 -> 1 micron) on wood, like basswood or any other smooth, firm & tight-grained wood. For the large carbide-related reasons I mentioned earlier regarding apexing & refining D2, stropping needs to be done very carefully, so the apex doesn't get rounded over. Hence my preference for a firm or hard substrate, like wood.
 
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For reprofiling any blade I find it so much easier to just use a belt sander with an angle guide. Works every time. Then onto whatever your progression is. 220 deburred for kitchen work is good enough. You only have to do this one time. For edc you can go to wherever you want after you profile the edge.
 
Obsessed with Edges said:
My stropping preference for D2 is to use diamond compound (3 -> 1 micron) on wood, like basswood or any other smooth, firm & tight-grained wood. For the large carbide-related reasons I mentioned earlier regarding apexing & refining D2, stropping needs to be done very carefully, so the apex doesn't get rounded over. Hence my preference for a firm or hard substrate, like wood.
Click to expand...
 
Obsessed with Edges said:
My stropping preference for D2 is to use diamond compound (3 -> 1 micron) on wood, like basswood or any other smooth, firm & tight-grained wood. For the large carbide-related reasons I mentioned earlier regarding apexing & refining D2, stropping needs to be done very carefully, so the apex doesn't get rounded over. Hence my preference for a firm or hard substrate, like wood.
Click to expand...
Thanks. I'll try this today.
 
BruceMack said:
In the past I have not been able to strop well with diamond paste or spray 1.0-0.5 microns. I don't seem to have those freehand skills. I can try again. Any experience with PSA aluminum oxide sheets? These are available from 2 woodworking sources at 0.3 or 1.0 microns. Silicon carbide seems limited to 5.0 microns. I could use the guided Sharpmaker rods with the paper applied in a thin strip and trailing strokes. Am I just chasing my tail?
Click to expand...

Get the diamond lapping film instead - it works better on high carbide steels and works well even on high vanadium stuff.

You can get smaller sized sheets very economically, used with a drop of mineral oil they won't load and can last a long time.
 
HeavyHanded said:
Get the diamond lapping film instead - it works better on high carbide steels and works well even on high vanadium stuff.

You can get smaller sized sheets very economically, used with a drop of mineral oil they won't load and can last a long time.
Click to expand...

What type/brand of films do you use? What grits? Source?
 
HeavyHanded said:
Get the diamond lapping film instead - it works better on high carbide steels and works well even on high vanadium stuff.

You can get smaller sized sheets very economically, used with a drop of mineral oil they won't load and can last a long time.
Click to expand...
Agreed ^. You really need to get the KME Lapping film kit. I just picked one up recently and it was toatley worth it. No more wavy edges and an absolute Mirror polish.
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