Reprofiling, Flattening Sharpmaker Rods and DMT Stone Questions

[gunmike1]

I recently reprofiled my Jess Horn flat to the stone with my sharpmaker diamond hones, which led my to buy a DMT X coarse benchstone for future reprofiling (including my Endura wave that I am doing now). After using the X coarse to reprofile the blades I went to use my sharpmaker brown rods as a benchstone in the back of the sharpmaker base and noticed they are far from flat, and think that may be why I have had troubles getting really clean edges on some of my knives.

I have 3 questions:

1. Can I use the DMT X coarse stone to flatten the ceramic sharpmaker rods?

2. Is the jump from DMT X coarse to Spyderco medium too large when trying to refine the edge I get with the X coarse? (I brought the X coarse finish all the way to the edge, should I have stopped slightly short of the edge and used a finer grit to get that last tiny bit of steel so the micro serrations weren't so deep? With the curvature of some blades that can be hard to do as certain portions like the belly tend to reach the edge before the choil and the tip.)

3. What tips do you have for getting the edge near the choil reprofiled all the way down. It seems like no matter what I do that is the part that needs the most work to get all the way reprofiled. I tried pushing striaght forward on the stone with no draw to get it more time on the abrasive, but it is still a very slow process.

It seems like the Spyderco mediums have a really hard time getting the microserrations from the X coarse all the way out, and as such there are parts of the edge that just want to catch when push cutting newsprint. From using the DMT the diamonds just seem to cut much better than the ceramic stones at light pressure on ZDP and VG-10, but maybe the sharpmaker rods would work better when they are true and flat. Would it be better to go to DMT Coarse or Fine after the X coarse, and then proceed to my microbevel of choice? My anniversary is coming up, and I think my wife would spring for a couple more DMT benchstones, and if the other grits work as well as the X coarse at sharpening high carbide stainless I know I will get good use from them. Of course the Spyderco benchstones would work better for me than the rods on the Sharpmaker base when I am reprofiling, but funds only allow so much new equipment at a time. Any help is appreciated.

 

[Cliff Stamp]

1. Can I use the DMT X coarse stone to flatten the ceramic sharpmaker rods?

Yes, but it will be very slow, wear the stone and produce a non-medium surface on the stone. They are defective, return them.

Is the jump from DMT X coarse to Spyderco medium too large when trying to refine the edge I get with the X coarse?

It is generally easier to not make such a jump, I usually go x-coarse DMT, fine DMT -> Spyderco ceramics.

I brought the X coarse finish all the way to the edge, should I have stopped slightly short of the edge and used a finer grit to get that last tiny bit of steel so the micro serrations weren't so deep?

Yes, assuming that last bit of edge is actually quality steel.

What tips do you have for getting the edge near the choil reprofiled all the way down. It seems like no matter what I do that is the part that needs the most work to get all the way reprofiled.

That is because that is where you start on the stone, think about how much of the stone that part "sees". You place the choil on the right side of the stone then push away while drawing along the stone. The choil area is immediately moved off of the stone while the forward part of the knife gets drawn through the entire width of the stone. In addition to that there are a lot of lazy grinds which thicken significantly in that area. Take a small diafold or narrow waterstone or file and just cut it off directly.

-Cliff

 

[db]

I have 3 questions:

1. Can I use the DMT X coarse stone to flatten the ceramic sharpmaker rods?

Yes you could but I don't think I'd do it.

2. Is the jump from DMT X coarse to Spyderco medium too large when trying to refine the edge I get with the X coarse?

Yes it is a pretty big jump. I use another stone between them. I think the DMT fine would be a good one.

3. What tips do you have for getting the edge near the choil reprofiled all the way down.

Yes same here you just need to work it more than the rest, sometimes I even use the corner of the hone I'm useing on that part.

 

[gunmike1]

Yes, but it will be very slow, wear the stone and produce a non-medium surface on the stone. They are defective, return them.

Will do.

It is generally easier to not make such a jump, I usually go x-coarse DMT, fine DMT -> Spyderco ceramics.

DMT Fine and X fine are on my Anniversary gift list. Maybe I should make it a DMT Fine and Spyderco medium benchstone in case I have to ship off my defective rods when I ask for replacements.

Yes, assuming that last bit of edge is actually quality steel.

How will it be apparent if it isn't quality steel any more? Behavior after sharpening, or anything visual under magnification?

That is because that is where you start on the stone, think about how much of the stone that part "sees". You place the choil on the right side of the stone then push away while drawing along the stone. The choil area is immediately moved off of the stone while the forward part of the knife gets drawn through the entire width of the stone. In addition to that there are a lot of lazy grinds which thicken significantly in that area. Take a small diafold or narrow waterstone or file and just cut it off directly.

Yeah, it is always more obtuse on my knives, and like you point out it barely is on the stone when you sharpen it. That is why I tried some strokes straight down the stone so that the choil "sees" the stone the whole way, but the knife just doesn't feel right to me when I don't have the draw in my sharpening stroke (it feels like I may be doing bad things to the edge, like tearing out chunks, it just feels rougher). I will have to get a diafold or small stone like you suggest to better take care of the choil area.

 

[HoB]

2. Is the jump from DMT X coarse to Spyderco medium too large when trying to refine the edge I get with the X coarse? (I brought the X coarse finish all the way to the edge, should I have stopped slightly short of the edge and used a finer grit to get that last tiny bit of steel so the micro serrations weren't so deep? With the curvature of some blades that can be hard to do as certain portions like the belly tend to reach the edge before the choil and the tip.)

I do that "jump" frequently. I agree with Cliff, that it is better to put a step in between, but it is quite possible if you spend a little bit more time on the grays.

 

[Cliff Stamp]

DMT Fine and X fine are on my Anniversary gift list. Maybe I should make it a DMT Fine and Spyderco medium benchstone in case I have to ship off my defective rods when I ask for replacements.

Spyderco benchstones have a huge advantage over DMT due to the fact that the entire thing is a abrasive, corners and all sides. However the DMT x-fine is a distinct grit not exactly replicated by the Spyderco's. There is some arguement that diamonds produce sharper edges on the high vanadium steels and I don't discount the work of Elliott and others but would like to see more repetition of the work as often it is just single runs and there can be too much variation in one run to the next simple due to the difference in the steel. If you are doing push cutting you definately would see a benefit from raising the finish above the DMT x-fine, but for most general work, even the 600 is fine.

How will it be apparent if it isn't quality steel any more? Behavior after sharpening, or anything visual under magnification?

It won't form clean, under magnification the edge breaks apart and doesn't have a uniform scratch pattern. The edge retention will be horrible as it will break/bend in a highly random manner. If you look at a worn edge they are highly distorted, the metal has been pushed past its plastic limit and it is highly fatigued and very weak. I recently started making a few light cuts into stones before sharpening which sounds really counter productive but quite frankly if you leave that weakened metal on the edge it will sharpen faster but go dull way quicker. It is the same reason that you note someone who smooth steels knives to sharpen them does it extremely frequently compared to someone who uses an abrasive.

...but the knife just doesn't feel right to me when I don't have the draw in my sharpening stroke

I have the same reaction, there is a similar problem with sharpening the heel of many forged kitchen knives due to the thick steel near the bolster which often induces a large hollow to form in the edge after a lot of sharpening. I recently had to hack that off on a knife I sharpened. I just used an angle grinder.

-Cliff

 

[Jeff Clark]

A belt sander will cut faster than a diamond hone and lets you sharpen up to the choil or ricasso.

When I sharpen the base of an edge manually I use two hands. I control and push the blade with my left hand which helps keep my honing stroke perpendicular to the blade. This lets me sharpen the base of the edge. It is easier to use the belt sander.

 

[gunmike1]

Spyderco benchstones have a huge advantage over DMT due to the fact that the entire thing is a abrasive, corners and all sides. However the DMT x-fine is a distinct grit not exactly replicated by the Spyderco's. There is some arguement that diamonds produce sharper edges on the high vanadium steels and I don't discount the work of Elliott and others but would like to see more repetition of the work as often it is just single runs and there can be too much variation in one run to the next simple due to the difference in the steel. If you are doing push cutting you definately would see a benefit from raising the finish above the DMT x-fine, but for most general work, even the 600 is fine.

I think I may just go woth the Spyderco benchstones (or simply my Sharpmaker, which I have up to ultrafine on already) to get past the DMT 600. It seems to me that there is a big advantage in having the whole stone as an abrasive, for instance as long as you hold the angle right you can sharpen serrations on the corner of the Spyderco benchstones. Since I'm starting to deal with single digit main bevels I'm guessing my fine and ultrafine stones will be getting more work.

It won't form clean, under magnification the edge breaks apart and doesn't have a uniform scratch pattern. The edge retention will be horrible as it will break/bend in a highly random manner. If you look at a worn edge they are highly distorted, the metal has been pushed past its plastic limit and it is highly fatigued and very weak. I recently started making a few light cuts into stones before sharpening which sounds really counter productive but quite frankly if you leave that weakened metal on the edge it will sharpen faster but go dull way quicker. It is the same reason that you note someone who smooth steels knives to sharpen them does it extremely frequently compared to someone who uses an abrasive.

I have had this happen, and had to sharpen several times to fix the problem. I will try cutting straight into the stone (I actually have been doing this with bad burrs anyway) before sharpening and see if this helps me avoid those crumbling edges.

 

[gunmike1]

A belt sander will cut faster than a diamond hone and lets you sharpen up to the choil or ricasso.

When I sharpen the base of an edge manually I use two hands. I control and push the blade with my left hand which helps keep my honing stroke perpendicular to the blade. This lets me sharpen the base of the edge. It is easier to use the belt sander.

Well, the $30 Harbor Frieght belt sander is in my price range, I just have to build my workbench so I have somewhere to put it (I have most of the wood except for the top, which will be butcher block since I am mounting my reloading press on it). I can start out on crap blades to try avoiding ruining the temper. How thin of an edge do you limit yourself to when belt sanding? For instance the edge on my Jess Horn is extremely thin now, and I'm not sure that I would put it anywhere near a belt sander, even if I did know what I was doing. Most of my knives, like the Endura Wave and other Sabre ground blades it seems like I would save myself huge amounts of time with a belt sander compared to my DMT X coarse.

 

[Cliff Stamp]

How thin of an edge do you limit yourself to when belt sanding?

There are small changes, however most steels will conduct heat the same and thus you can use cheap knives to see how quickly they build up heat. You will see quite quickly that if the knife is of any size it is very difficult to overheat because the rest of the blade basically sucks the heat out of the edge. The only real concern I have found is grinding right on the platen with really high wear steels which are very thin < 0.010" and acute. There is a lot of metal in contact with the abrasive and nothing for the heat to dissipate into. Better belts would allow cutting at a lighter pressure. But again, just do some grinding with a cheap knife and watch how hot it gets under your finger tips.

-Cliff

 

[gunmike1]

Cliff (or Jeff), what grit would you recomment for the $30 1" by 30" Harbor Freight cheapie sander for basic reprofiling of the cheap knives I will start out on? Maybe 80 or 120 Aluminum Oxide? I have several cheapies that I don't mind sacrificing, but I would prefer to really thin them out and see what some of these old mystery steels are capable of with thinner grinds without completely destroying too many.

 

[Cliff Stamp]

80 is the maximum and the only reason I use that is that I can't buy anything finer. However this will tear massive pieces out of the edge of a acute edge so on precision cutter I grind almost to the edge so there is just 0.1-0.2 mm left and hand grind that. This isn't as hard to do as you might think because as you get closer to the edge then the speed of metal removal slows way down.

-Cliff

 

[Jeff Clark]

If I go below 80 grit it is only to rough down something that is in really bad shape like a garden shovel. I have used it to rework the edge on a throwing knife for example. A new 80 grit belt is still pretty rough though a worn 80 grit belt starts to have some general utility. For things that are more like sharpening I tend to start with something in the 120 to 220 grit range. A worn 120 grit belt is not bad, but a newer 220 grit belt gives me neater results. I guess that I should point out that my frame of reference tends to be sheath knives and large kitchen knives. If you are mostly conserned about folders I would tend to stick to 220 to 600 grit belts.

 

[Bill DeShivs]

www.jantzsupply.com has belts up to 600 grit. A 320 or 400 grit belt will remove metal quickly. If I am grinding a blade from a blank I start with 80 grit. I can't imagine using 80 grit for any type of sharpening.
Bill

 

[Cliff Stamp]

I can't imagine using 80 grit for any type of sharpening.

It works well for aggressive slicing, though in general it is excessive unless you are using fairly obtuse edges like 15+ degrees per side.

-Cliff

 

[gunmike1]

Thanks for the replies, it looks like I should probably start in the 320 to 400 grit range. Mainly I will just be doing some reprofiling on folders, though I do have some kitchen and medium sized fixed blades that I inherited that need some work.

 

[gunmike1]

Well, today I ordered the DMT Fine, along with the Spyderco Medium and Fine Benchstones. Hopefully I can get the belt sander soon.