I have a Grunt as well, but mine is an older one made with Aus8 from Seki Japan. I have no idea which is better because as mentioned earlier in this post there is VERY little worthy info yet known about the chinese 10cr17 steel being used.
In America, it would be a common assumption to be very skeptical about things being made in China. But, the reality is China is going through a HUGE economic revolution. Some items are still being made "Cheap". But, many things are being made to much higher levels of quality to help satisfy the higher demands of many more prosperous incomes in China these days. But, the "cost" is still way lower than things made in the U.S. or most other countries. As stated, for $20.00, I am confident that the Grunt is a steel. I paid more for my Seki Grunt. I have had mine for 3 years or so and probably paid closer to $50.00. Even for $50.00, I consider it a great knife. But, I don't know how the Seki version compares to the China version.
It sounds like the China versions have the same very sharp full convex edge out of the box. If so, that is almost worth $20.00 alone!
I LOVE a good sharp well profiled convex edge from the factory!!!
In regards to "stropping" on cardboard. For hair shaving sharp, stropping is the key. I use a belt sander for mainly getting the profile set. Then depending on the knife, I might do a number of different methods to finish the edge - including stropping to get hair shaving sharp.
Most factory knives including Busse and kin come with a "functional" cutting edge. But, most any edge can be improved with a good profile and stropping.
When profiling an edge, you need to keep in mind what you are using the knife for. If it is going to be used for heavy chopping and such, the angle needs to be more obtuse to help prevent edge chipping or easy edge rolling.
If the knife is only for cutting, you can take the profile a little narrower. Different types of steel and different levels of steel hardness handle abilities for narrow profiles differently as well - So, often knowledge of steel AND experimenting is required.
If the knife is for chopping, I don't feel it is worth the time and effort for much stropping. But, if you have a good smaller task/chore knife that you use primarily for cutting tasks, a stropped edge to hair popping sharp is an addictive joy.
I typically profile with my knives with the belt sander and about 220 grit belts. I have been wanting to get other grits and a leather belt for my sander, but I have been wanting to upgrade my sander and my upgrade will be to different sized belts - so I haven't wanted to spend the money on belts until I get a new belt sander. However, for now, I have been doing pretty darn good with 220 grit on my 1"x30" sander.
I have a couple of differet "bar" type compounds that work VERY well and surprisinbly fast.
But, to answer the question about cardboard: Yes, Cardboard is Excellent for that final touch. Cardboard or similar rough paper like grocery bag paper or semi-rough post cards, magazine insert cards, some sheet paper or envelopes even if no seem in the way - all work at removing the final little micro burrs on an edge. Stropping with these materials can take the final step from draw cutting paper pretty well to push cutting paper really well!
BUT, you can't get an edge profiled or fix a lot of edge work with cardboard. You have to have a pretty good edge already and use cardboard as "Touch up".
Since the Grunt already comes from the factory with a good edge, I am sure Ken Warner is only referring to maintaining the factory edge with touch up stropping on cardboard. From time to time, you will probably need to do some more tweaking on the edge with more agressive belts.
There is a "catch" with convex edges: good convex edges are not "really" compatible with stones and most of the sharpening "jigs" on the market.
Conversely, flat edges are not "really" very compatible with strops (for most people).
But, personally, I am a huge advocate of convex edges. I could write a lot more about convex edges and what I consider advantages, but I would probably double or triple this post and I don't have time for that.
Bottom line: Flat angled blade edges can and do cut well. Spyderco makes some of the best factory sharp edges I have seen and they are flat. The jig Spyderco sells also makes flat edges. So, if you want flat edges, get a good jig because it is hard to maintain flat by hand. At some point, if you sharpen by hand on stones, you start to convex the edge anyway. But, again, a stone is not ideal for convexed edges. So, if you are going to have convexed edges, figure out how to do it best.
Once you figure out how to do it and have a few basic tools for setting and touching up profiles and some stropping tools, I find it much easier and faster than stones and stone type jigs. But, this may just be a personal preference.
For the record, a cheap 1"x30" belt grinder and a handfull of belts, including a leather strop belt or flat leather strop and some compounds can "EASILY" cost less than a "decent" sharpening jig and "decent" stones. Good quality water stones are VERY expensive! You can have a NICE belt sander like a Kalamazoo by the time you pay for good water stones.
Instead of me writing a bunch of thoughts on sharpening, I recommend doing some research especially on Knifeforums, but also Bladeforums.
Here is a good start:
Sharpening My Way - by Jerry Hossom ----------------
In regards to the Grunt vs. DM vs. RMD:
For my uses, I still prefer the RMD quite a bit followed by the DM 2nd. But, if considering price, the Grunt is an ABSOLUTE STEAL!!!! Every now an then, you might want a less expensive beater knife. Stainless steel is better for keeping in the car and such. (* I have said this before, but knives kept in cars are subject to temperature and humidity changes that cause moisture to condensate on steel causing rust. Carbon steel knives in leather sheaths in a car is almost as good a recipe for rust as leaving a carbon steel knife in a mud puddle for a few days.)
For a smaller knife, the Grunt offers a reasonable amount of chopping that a bunch of you guys like. The Grunt won't out-chop the S6, but it should out-chop the DM or RMD.
However, the Grunt is not as nimble for certain task uses as a DM or RMD.
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