Benchmade 940
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10/08/2015 at 12:14 am #29152
This 940 has a S90V blade and has proven to be my nemesis! I have tried sharpening this blade several times each at 18 dps. Last night I tried again trying to pay extra attention to raising the burr. I thought for sure I got it this so I proceeded through all my paddles and when I removed it from the vise it will barely shave the hair in my arm. I don’t understand what I’m doing wrong with this knife, hopefully one of you can shed some light! Here is the steps I took last night:
1. Put marker on edge, alternating strokes until all removed with 80 grit diamonds
2. Begin to raise burr it took about 55 strokes with 100 grit diamonds to raise a burr that I could feel with fingernail the entire length
3. Raise burr on opposite side the entire length
4. Returned to alternating strokes progressing from 100 grit to 1000 grit diamonds each stone 50 strokes per side
5. Ceramics 1200, 1.5, 1600, .5 grit each 50 strokes per side
6. Diamond lapping film 1, .5 each 59 strokes per side
7. Decreased angle to 17dps balsa strops 1, .5 diamond paste each 50 strokes per side
8. Increased angle to 18dps repeated step #6
9. Decreased angle to 16dps leather strops 1, .5 diamond paste each 50 strokes per sideIt will shave hair on my arm with a lot of pressure but not like it should! I ran the edge across my thumbnail and it just glides like there is a flat edge, usually they want to slice in or grab even with little to no pressure.
I’m not a beginner but far from a pro! I’ve sharpened close to 150 knives using pretty much the same method with great results!
Do any of you see anything wrong with what I’m doing and could you explain how to do it better?
Thanks, Chris
10/08/2015 at 3:14 am #29154I think it’s time you graduated to a very good loupe or a USB microscope. When something isn’t producing the results you expect, you need to see it up close.
10/08/2015 at 9:38 am #29155That’s a good tip! A cheap 60 x loupe (technically a microscope) costs only a few dollars.
Your procedure sounds allright, I cannot think immediately of something you’re doing wrong. Are the 80 grit stones worn in? Otherwise you may need to spend some more time on the 100 grit stones. Also, how is the performance of the edge before stropping?
Molecule Polishing: my blog about sharpening with the Wicked Edge
10/08/2015 at 10:54 am #29156I too have found s90v to be troublesome somewhat, but not like what you are describing.
What happens if:
– take it to 1k grit raising a burr on both sides at some point along the way (since you are already there at 18 dps, just use your 600 grit paddles to generate a burr at that angle).
– remove the burr w/ edge leading, alternating passes going very lightly at the end (maybe 10-15 pps
– increase your angle to 22 dps and microbevel w/ your 1k stones, again, edge leading, alternating, WHISPER light passes on the microbevel – you don’t even want to be able to see this bevel hardly.
– leave your same angle and move to your 1um diamond pasted balsa strops, edge trailing/alternating for about 5-10 LIGHT (but not too light) passes.I have had excellent success w/ this method, interested in your results.
10/08/2015 at 7:52 pm #29157I have a few questions, sorry no answers:
Have you sharpened a 940 before? Reason I ask is I have a few 940s and find them difficult correctly set in the vice since they are long and don’t have very much flat area at the top of the spine to set in the vise.
Have you (or anyone listening) sharpened S90V before? I have heard it was hard to sharpen but figured it would be easy with WEPS maintaining a consistent angle and having the diamond stones.
Have you tried slicing news paper after every stone? This is somewhat possible with the knife still in the vise. Just wondering if you can tell where it goes wrong ? I wonder if you never got a good edge after the 80’s and didn’t spend enough time with the 100’s. I think Josh is right though, if you can get a burr at 600 then go from there.
Josh, can you sharpen S90V like normal? I.e. without a micro bevel.
I normally don’t use 80’s. I find them too aggressive and 100’s will get a re-profile done. When I have used the 80’s I spend a lot of time on the 100’s. I raise I burr both sides to make sure all is still good. Then I really do a lot strokes to work out the scratches.
Withe some steels more than othersI can raise a burr at every diamond grit with 2-5 strokes. Just enough to barely feel it. I don’t do it purpose, just noticed it one day after doing 2+ strokes on the same side by accident. It may not hurt to to do 5 stokes per side at the start of each diamond.
I always check my edge with a loupe and finger and sometimes paper after the 100’s. It everything is going well the edge should be sharp but still rough.
I am looking at getting this knife too as well as another BM in S90V.
10/08/2015 at 7:55 pm #29158Josh, can you sharpen S90V like normal? I.e. without a micro bevel.
.Pretty much, but I have found that I do need to strop lightly to bring out that extra hair popping sharpness/clean up the edge slightly.
10/08/2015 at 8:15 pm #29159I have 2 other BM 940s that I’ve sharpened both with S30V they are hard to secure in the vise but I am able to get them both to split hanging hair using the same method. The gen 3 vise makes it way easier to secure!
I’m gonna try some of you alls suggestions but first I’m gonna go shopping for a loupe so I can hopefully see the edge better! I have a 2.5X but it don’t cut it.
After reading your feedback and talking to a knife maker buddy I suspect I never really got the edges to a true apex.
I’ll post my findings later!Thanks everyone!
10/08/2015 at 8:19 pm #29160I have 2 other BM 940s that I’ve sharpened both with S30V they are hard to secure in the vise but I am able to get them both to split hanging hair using the same method. The gen 3 vise makes it way easier to secure!
I’m gonna try some of you alls suggestions but first I’m gonna go shopping for a loupe so I can hopefully see the edge better! I have a 2.5X but it don’t cut it.
After reading your feedback and talking to a knife maker buddy I suspect I never really got the edges to a true apex.
I’ll post my findings later!Thanks everyone!
Begin to raise burr it took about 55 strokes with 100 grit diamonds to raise a burr that I could feel with fingernail the entire length
If you did this then you definitely apexed the edge… the question is if you hit the apex w/ each subsequent grit =)
A loupe is a great idea! I currently rarely use on, even when reprofiling to 15 dps and mirroring an edge to hair whittling sharpness… but I use a very specific method that works well. I use a bright flashlight hitting the edge at different angles and reverse grind direction w/ each subsequent grit. This allows me to make sure I have completely erased the scratches from the previous grit – a tip I picked up from Clay. The only time I use my usb scope is when I am doing a straight razor, but that’s because the apex has to be absolutely perfect for a clean and smooth shave 🙂 hehe
10/09/2015 at 11:23 pm #29171That is exactly what I was thinking. If hit the apex with your first stone how can you not with the next one? Let’s assume diamonds and the angle doesn’t change at all.
Flash light is also a good trick. With the loupe it works great, but can blind you when the edge starts getting polished.
10/09/2015 at 11:35 pm #29172That is exactly what I was thinking. If hit the apex with your first stone how can you not with the next one? Let’s assume diamonds and the angle doesn’t change at all.
Flash light is also a good trick. With the loupe it works great, but can blind you when the edge starts getting polished.
It’s easier than you may think… an angle variation of .1-.2 degrees would be enough. For instance… let’s say you were doing edge leading passes from heel to tip w/ the 100 grit stones and when you went to the 200 grit stones you switched to edge trailing from heel to tip (i.e. up and away sweeping passes). You just screwed everything up… there is about 1 degree of play in between the paddles and rods and when your paddle is fully extended at the tip instead of fully extended at the heel that will create a double facet in one area and not hitting the apex in the other :woohoo: :huh:
I always use s USB scope when doing straight razors and you would be surprised that you will think that you are hitting the apex and still have a little bevel left there hehe. So a loupe is a great recommendation, especially when someone is starting out but it is good if you want a perfect edge everytime for anyone.
10/09/2015 at 11:42 pm #29173I don’t have a WE yet, but when I get one, that is the main reason why I intend to go heel to tip with every stone. I can live with some angle variation from heel to tip, O doubt that it would be an issue for what I do in the kitchen. However with some knives and steels, it is tough to live with not hitting the apex.
Accept at the end on a finishing stone and with stops where I would use light edge leading strokes.
Working to make knife.wickededgeusa.com a great forum!
10/10/2015 at 2:31 am #29176This one looks like the loupe I use. 60x magnification and a light built in. Works great.
Molecule Polishing: my blog about sharpening with the Wicked Edge
10/10/2015 at 5:01 am #29177Ok the overdue update…
I found a 60 – 100X loupe and when I looked at the edges it seemed like it came to an apex but it looked serrated. So, I figure I just didn’t work it near enough. I decided to start back at 400 diamonds and progress from there. The one thing I did that I’ve never tried before is I alternated patterns like, up and away, up and toward, and down and toward, I did each in sets of 100 strokes. I may have gone overkill on the # of strokes but it seemed to help a lot. On the diamonds I did 800 strokes per each grit then on the ceramics I did 1000. I also slowed down and made sure I was consistant with my pressure and completely flat with the paddles. At the end of each progression I cut newspaper and with each progression the cut would get noticibly smoother. I also used my angle cube and measured each stone on each side throughout the process, it varried from 8.10° – 8.50° on the left and 8.10° – 8.45° on the right (i’m not sure how to compensate for this). It now shaves the hair on my arms effortlessly and splits a hanging chest hair at any spot on the blade from both sides, it is also the best polish i’ve done so far!Thank you all for your input!!
Chris10/10/2015 at 5:07 am #29179Attachments:10/10/2015 at 6:50 am #29180Very nice! Gotta love the Benchmade 940. That’s some nice looking carbon fiber on that knife.
Alan
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