Best way to bring edge angle down?

DaveH

DaveH

Joined
Dec 2, 1999
Messages
12,249
I have two sharpening systems, one is an older diamond clamp/angle system, like Gatco but with narrow stones, I also have a Spyderco sharpmaker.

I can do the magic marker trick, I want to bring the edge angle down (it's a sebenza) so it will cut like a ZDP-189 Caly.

Should I just do Spyderco at 30 degrees all the way to start, giving me 15 per side? Or should I use the angle system (which is a bit sloppy in holding the angle) which I think goes down to 10 degrees per side. But I only have the "fine" diamond which I think is around 600 grit.

Also if I put Flitz on leather for a strop, will it act similarly to the chromium oxide green which I don't have?

Thanks
 
Since you are simply slimming out the edge, precise edgeholding is not an issue. I would go with the clamp system. Once you have brought down the edge angle (say 10-12 deg per side), clean up the edge on the Sharpmaker on the 15 deg. setting. Since you finish on the Sharpmaker anyways, it doesn't really matter which grit you are using on the clamp system, even though a finer grit will leave you with less work on the Sharpmaker.

I would recommend against Flitz on a Leather strop. Not so much for fear of the blade as for fear for the leather. Unlike a stropping compound I believe Flitz contains chemicals which aid in the polishing the metal and which might not be the best for the leather. Mmmmh, continuing to think about this, those chemicals usually remove a small amount of material by a chemical action which might be detrimental to your edge as well. I doubt it will do significant damage, but it might take away the keen edge that you are trying to build. This is pure speculation though. I have never tried it.
 
I recall reading a couple of times that the Spyderco brown stones are equivalent to about 600 grit. So if your angle system uses only a 600 grit stone, you're not going to save time using the angle system, although it gives you the choice of 10 degrees per side.

I've taken numerous knives down to about 10 degrees per side using an extra course diamond hone (it takes about 10 minutes), but in each case it was a pure "user" knife. The resulting bevel is not always "pretty." As an example I did this with two older Buck 110s that have 440C blades that I got cheap.

I wonder whether you should to go straight to a 10-12 degree per side unless you're really convinced that the CRK S30V will perform well and not chip at that angle given the media you plan to cut. Although the performance of the knives I've thinned to about 10 degrees per side is very impressive, I've also had excellent performance with knives I've thinned using the 30 degree setting on the Sharpmaker and finished with a microbevel using the 40 degree setting. So, my advice would be to use the marker and the 30 degree setting on the Sharpmaker, establish that as your edge, and then finish with a few light strokes on the 40 degree setting, and see if the performance satisfies you.

You can always go thinner, but you can't add metal back.
 
30 degrees will work okay and you already have the Sharpmaker setup so you can do this easily. If you want to hurry the process along (tape the blade first to avoid any scratches) you can take a cheap two-sided whetstone from the "depot", rest in against the 30 degree gray rod and use the same motion. You should clamp the holder down and be careful because you will have fingers on the other side of the protective brass rods. However the two-sided whetstones are not so wide that you can't grip them on the edge and hold them in place against the rod in the 30 degree setting. The only thing the rod does is give the whetstone the proper angle.

Once you have a reasonably sharp edge with the whetstone switch to the grayrods still in the 30 degree setting and make some passes to polish the edges. Then switch to the 40 degree setting, gray edge, gray flat, white edge, white flat, sharp at every step, and you will end up with a knife almost if not razor sharp.
 
Is your clamp system the DMT one? If not can you get a coarse hone for it? I'd say a coarse hone along with your 600 hone would be a great first step before moveing to the Sharpmaker. As the Sharpmaker rods have been compared to 600 grit I'd say they are much finer than that and will not cut as fast as your 600 diamond.
 
I moved my large Sebenza back to 9 deg / 13 deg per side - very noticable improvement in the light cutting that I do. Since I had no chip out or edge roll over in 3 weeks of carry - I am moving to 8 deg / 13 deg over the next few days.

On the Edgepro - I needed to go to a 120 stone to remove material at a reasonable pace - then go to 180 / MF / 220 / 320 / 600 to achieve a nice prof looking finish on the wide primary bevel.

Moving from 9 deg to 8 deg primary bevel removes the stonewash finish from the entire tips area - so stay at 9 or above if that would bother you.


MAT
 
Mat, how is your sharpening frequency, are you touching up the blade more or less than before?

-Cliff
 
Sharpening frequency - 3 times - all because I was experimenting/learning the steel and what it likes:

experimented with polishing tape (duller in paper tests) - brought to tiny burr with 320 stone then cleaned off with 600 wet then 600 dry to finish

experimented with 1200 round ceramic rod - duller in paper test - repeat as above

experimented with lee valley strop and a hint of green stuff (actually what was left after waterless hand cleaner) - duller in paper test - repeat as above.

Extreme light duty paper / string / veggie&cutting board work.

Now in process of pulling back transition angle. I think there may be something there with the rod and strop for touch ups - but my technique must be lacking.

MAT
 
Oh - there really was no "before" ie stock angle - stock it shaved but cut like a sticky axe in my applications - unacceptable.

MAT
 
Paper test was heavy bond printer paper held with one hand buy one corner - blade brought to paper - slicing cut from base of blade to tip - qualitative measurments against standard (now shelved buck 110 with 425MOD blade finished 11/13 deg then polished with tapes) - looking for pressure to cut, eveness of cut, sound of cut, consistancy across blade, and then a mild stress test of about 30 cuts mostly through page to roll any burr that may be fooling me by standing straight up.

Once a blade is close to where I like them, the cuts are usually making strips about 1/4" wide. I use a reference blade only to keep my imagination in check.

The slicing cut I make is very slow in the blade axis, but taking almost a full depth of cut on the printer paper.(more of a press cut I guess) I don't complete the cut - only to stop a pile of ribbons ending up on the floor.

My test always degraded the same after messing with the 600 wet then dry stone finish on the Sebbie - consistant cut that required more pressure, was smooth in action but just draggier and duller across entire blade.

The 425MOD steel just kept getting smoother and easier in its cutting as the tapes were used - stropping did no better but blended the look of the bevels. I doubt the strop will be used much now that I have the tapes.

MAT
 
Interesting work, I didn't find solid edge retention with the small Sebenza at low edge angles, but it did respond well to high finishes, generally I would take it to either 4000 waterstone or a fine natural chinese waterstone and then some very light stropping on chromium oxided loaded leather, just a few passes and then a cleaning on plain leather and/or newsprint. It would then push straight into newsprint with no slice and make cuts very easily. The one I have consistently responds very well, possibly the best stainless I have seen in that regard with the exception of the Calypso Jr. which is in the same class, possibly a little better in that regard. Have you tried similar with some of the coarse grained / heavy carbide steels like D2 or 440C or S60V?

-Cliff
 
I have no experience with the other steels - the knives I sharpen are a bunch of home-made carbon steel kitchen knifes made from large bearing shells (Dad made before he retired - I rec'd the early models until he found the shape and handle style he liked best - incredible cutters but softer steel), 3 old Bucks, few chisels and scissors, and this new Sebbie. My wife loves these 8 dollar mickey mouse IKEA veggie knives - so I keep them tuned up and steeled. I brought a couple just to get a feel for the shape of the knife - now I can't buy a good one 'cause she just raves about these cheap ones

I'm going to keep a high polish on the primary angle of the S30V but not drop below 13 deg a side on the final cut angle - then play with polishing the cut angle bevel out to the edge.

For all I know - I'm still in the steel that was annealed during the inital blade grinding - and that is the reason I need to finish with a stone moving into the edge rather than a tape / leather strop moving away from the edge.

MAT
 
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