Sharpening a spearpoint fixed blade with a lot of belly

[MatthewSB]

I am having an aweful time trying to sharpen my spearpoint Strider MT. It's hollowground S30V, and seems very hard to sharpen compared to any other knife I've owned. I can get the straight portion, at the base of the blade, hair flinging sharp but I cannot seem to get the curved portion to sharpen. Factory spec's a 22.5 degree angle per side. I've been using Spyderco fine and ceramic flat stones and a leather strop with compound.

I'm considering just redoing it with my Sharpmaker at 20 degrees per side. Any reason not to?

I've never had an S30V fixed blade before, and I'm honestly afraid of the blade chipping if I thin it out too much. I was told that Strider heat treats their S30V differently and not to worry about it, should I?

Any basic sharpening advice for a spearpoint fixed blade, where the straight portion gets sharp easily, but not the curve?

 

[Kershaws]

I've had this problem with many deep-bellied blades. I never managed to get the top portion straight no matter how much I varied my technique. The only way I could get the entire edge straight is to sharpen it with a clamp system. (Lansky, Wicked Edge, Edge Pro Apex) Lansky being the cheapest.
If you look at the edge you'll notice that the top portion of the edge near the tip is thicker than the straight portion. This is due to inconsistent angle. I'm sure you've messed the edge up alot so using the Sharpmaker will take a long time. I suggest you spend some $$$ on a Lansky system, preferrably the diamond set because it sharpens quicker

 

[awestib]

I don't have any experience with S30V, most of my experience is with O1, 52100 and 1095, a bit less with A2. What I know about S30V is from what I read and bookmarked here on BF and online. It seems, at least based on Ankerson's edge retention test, it is as wear resistant as D2, ATS34, S35VN and Elmax with a variety of hardness. This is pretty good (although it was placed in the group 5, so there were 4 groups of steels better than S30V in edge retention!), however, it seems to be a "chippy" steel. That is possibly the reason why your knife comes with that obtuse edge angle (44 degrees inclusive). How tough it is I can not say, I get a garden variety of results online but it seems to be less tough than A2 for instance.

First question then, do you want to reprofile that blade or do you want to keep it at that obtuse angle? If yes, you could do it on the Spyderco SM but even with the diamond stones it would take a lot. Preferred here would be a coarse diamond stone or waterstone, done by hand. Then you can easily use your Spyderco SM with the 20dps setting. If no, you will not have an option other than freehand or with a guided system that you can set to that factory bevel.

IMHO, almost all (literally all) factory production knives come with too obtuse and often uneven, dull edges. They all cry for reprofiling and in my opinion, that what makes the knife mine. Some people however would not like that and that's cool.

 

[kwackster]

About two months ago i did this comparable Strider model in S30V steel on my Paper Wheels, as the factory edge angle was 50 to 55 degrees inclusive according to my Tormek angle gauge, and far, far removed from being even paper cutting sharp.

Grit progression: reprofiled the edge with a Paper Wheel with 220 grit SiC, refined the result just a little with a second Paper Wheel coated with 15 micron diamond compound, and removed the extremely tiny burr with a third Paper Wheel coated with 0.25 micron diamond compound.
Imo a good mix between bling & bite, and as a knife a whole lot more useful than it was.
The new edge measures 35/36 degrees inclusive (thinner would have made the bevels much wider, something the owner did not want), and it can both treetop armhair and slice single layer toilet paper along the entire length of the edge.

I simply don't have the time to do these kind of things by hand.

 

[bgentry]

I'd guess you haven't reached the edge of the edge in the belly of the blade. Try coloring the cutting bevel with sharpie and then doing some strokes on the stones you are using. See where the sharpie is being removed. If there is sharpie remaining on the edge of the edge, then you haven't gotten there yet, either because the blade grind is inconsistent in that area, or you aren't following the curve with the correct motion to get there.

Watch this video from Ken Schwartz explaining how to follow the curve of a blade:

[video=youtube;JFhUXgYS0Os]https://www.youtube.com/watch?v=JFhUXgYS0Os[/video]

Brian.

 

[awestib]

About two months ago i did this comparable Strider model in S30V steel on my Paper Wheels, as the factory edge angle was 50 to 55 degrees inclusive according to my Tormek angle gauge, and far, far removed from being even paper cutting sharp.

Grit progression: reprofiled the edge with a Paper Wheel with 220 grit SiC, refined the result just a little with a second Paper Wheel coated with 15 micron diamond compound, and removed the extremely tiny burr with a third Paper Wheel coated with 0.25 micron diamond compound.
Imo a good mix between bling & bite, and as a knife a whole lot more useful than it was.
The new edge measures 35/36 degrees inclusive (thinner would have made the bevels much wider, something the owner did not want), and it can both treetop armhair and slice single layer toilet paper along the entire length of the edge.

I simply don't have the time to do these kind of things by hand.

^2nd, I would not want to do that job by hand either and I forgot to mention power tools (be careful in unexperienced hands though given how easy it is to ruin the heat treatment) - good point Kwackster!

One more thing I just noticed in the OP - a spear point type blade does not even have a significant belly so it should not be too challenging to sharpen it properly. In my experience it is better to actually not follow the bevel as pointed out in Ken's video but rather keep the angle consistent and lift up the handle to follow the belly to the tip. Here are a few pictures that I think demonstrates it (the credit for the idea of those pictures in regards to the belly and handle height goes to HeavyHanded of BF):



Note that I did not turn the knife on the stone but only lifted up the handle as I sharpened along the belly towards the tip. I believe you get more consistency this way.

 

[MatthewSB]

This is very helpful. Thank you all so much for the advice, I'll give it another shot tonight.

I actually think I have a Lansky clamp system somewhere that I haven't used since I got a Sharpmaker, and to free hand sharpen on stones and strops.

Please share, what model is this?

 

[rutcrazed]

Kwackster, You sir make some very pretty edges...