Sharpening ZDP compared to VG-10

[nphelps4130]

I have learned a lot from reading posts about sharpening on bladeforums and I was hoping I could get some advice on sharpening my ZDP Delica.

I have a ZDP Delica and a VG-10 Delica. I have reprofiled both to a 30 degree included angle using a DMT X-coarse continuous-diamond stone and then sharpened using the Sharpmaker medium rods. After that I applied a 40 degree microbevel to each knife using the medium and fine rods on the Sharpmaker. I basically follow Sharpmaker directions - 40 or so strokes on the corners then flats of medium rods, then on to the fine rods checking performance along the way and doing more strokes if needed. I also de-burr along the way by making a few strokes at a much greater angle on the corners of the medium rods and then later on the fine rods to be sure that I have not created a wire edge. I am very happy with the results on the VG-10 Delica - the knife is very sharp and performs well. It push-cuts paper with ease, which is one of my main tests for sharpness.

The problem is the ZDP Delica. It just won't push-cut paper nearly as well. It is sharp and works well for slicing, but I am curious why I can't achieve the same result as with the VG-10. Is it the larger carbides in ZDP that make it a better slicer and less of a push-cutter? Or should I be able to achieve good push-cutting performance that is on-par with VG-10 with this ZDP knife?

I have been able to achieve consistently good push-cutting performance using the technique I described above with VG-10, AUS-8, and SAKs quite easily but ZDP is giving me a problem.

Now I also have a ZDP Caly 3 that push-cut like crazy right out of the box. I realize the different edge geometry and angle may be responsible for the better performance of the Caly 3, but at least this shows me that ZDP can push-cut quite well. What I can't account for is why the ZDP Delica performs so much worse than the VG-10 Delica which is identical except for steel.

Would you expect the ZDP Delica to be a worse push-cutter than VG-10?

 

[yablanowitz]

With stock geometry, yes. I reprofiled mine at about 10 degrees per side and use a 15 per side (30 degrees included) microbevel. The stronger ZDP-189 can handle the lower angle with no trouble. It could easily go lower than that, but I use it for a beater so I am keeping it where it is. Bear in mind the hardness of the two steels. It will take longer to achieve the same finish on ZDP than it does for VG-10.

The advantage of better steels is not so much the performance at the same angles as the ability to use lower angles with good results. If you want a real eye opener, send that ZDP Delica off to Tom Krein and have him flat grind it to a .010 thickness behind the edge. That will have it outcutting the Caly and still leave plenty of strength for most uses. I really feel the saber grind of the Delica and Endura do this steel an injustice.

 

[gud4u]

I agree with yablanowitz about the angles he chooses.

My own testing indicates that 10 degree main bevels with 15 degree micro-bevels is ideal for EDC blade, providing an excellent combination of edge stability with good slicing performance - suitable for slicing materials up to hardwoods such as ash or hickory.

If the 15 degree microbevels are applied carefully (avoid using the corners of the Shapmaker and avoid hard honing pressure), that step should effectively accomplish both:
- Deburring the main bevel edge, and;
- Providing a strong edge.

I'm ignorant about ZDP, since I have no ZDP blades, but the above certainly holds true for VG10, S30V, BG42 and D2. It's true also for ATS34, with the proviso that greater care may be required for burr-removal with this steel.

Unless you're chopping or batoning with the blade, an included angle of 40 degrees for a premium blade steel simply provides a less-sharp blade.

Hope this helps!

 

[nphelps4130]

Thanks for the info guys. The main reason I sharpen at 30 degree back-bevel and 40 degree micro-bevel is because it is so convenient with the Sharpmaker. If the Sharpmaker had a setting for a smaller angle I would probably try that, especially with the higher-end steels. But in all honesty, I have been totally satisfied with the performance of my knives with my current angles, except for this ZDP Delica. However, I do think that with this Delica I may send it to Tom Krein for a narrower grind as suggested. It seems that with a steel like ZDP it must be narrower to really bring out its strengths. What is the best way to contact Tom Krein?

yablanowitz, can you tell me why you would expect the ZDP Delica to be a worse push-cutter than the VG-10 with stock geometry? Is it because of the nature of ZDP to form larger carbides, and therefore it won't take as fine of an edge at a given angle? I do understand that one of the strengths of ZDP is to take a very narrow edge, but why would it under-perform VG-10 at the stock angle?

Thanks for all the help.

 

[yablanowitz]

I'm no steel guru, everything I know is field experience. The carbide content of ZDP seems to be Hitachi's trade secret. It just seems to me to be more difficult and time consuming to get the edge right on. Whether that is a result of large carbides, very hard carbides, overall hardness or just stubborn burr doesn't really matter to me, I just deal with the end product. One of my first observations on the Blue Sprint ZDP Delica was the thick grind really didn't show the steel to best advantage, especially compared to the ZDP Caly Jr. I suspect VG-10 has a finer grain structure or smaller carbides, as I have a much easier time getting a satisfactory edge on it.

I contacted Tom about regrinding my ZDP Endura by private message here on the forum. I think he may be set to accept e-mails as well.

 

[gunmike1]

What is the best way to contact Tom Krein?

479-233-0508 is Tom's number. I actually have it programmed in my phone, though you can contact him by e mail as well. I have had 3 ZDP knives and a couple others reground by Tom Krein and they are definately my best cutting folders. It is amazing what a thin edge can do for cutting ability. The difference in my ZDP Endura from stock to full flat grind with a splinter picker tip is pretty impressive. The knife went from a fat wedge to a nice, thin cutter that still has good durability with it's .010" edge. Tom does great work, and I can't recommend his regrinds enough.

Mike

 

[nphelps4130]

Thanks yablanowitz - I'm just trying to figure out if my experience with ZDP and this Delica is normal and I appreciate your info.

I will definitely get in touch with Tom Krein - it sounds like this Delica would be perfect for a regrind.

gunmike1, have you found that touching up and maintaining the knives that you had Tom Krein regrind is pretty easy? Would I be able to maintain the performance with the Sharpmaker at 30 degrees, for example? I assume the included angle after the regrind is probably well under 30, and then I could sharpen with a microbevel at 30?

 

[Knife_Geek]

nphelps4130 I had the same question before I had my E4 Waved reground by Tom. I had him setup the edge so that you literally just use the sharpmaker as normal but the a massively reduced overall thickness behind the edge is its advantage not really the edge angle.

 

[sodak]

Thanks yablanowitz - I'm just trying to figure out if my experience with ZDP and this Delica is normal and I appreciate your info.

I will definitely get in touch with Tom Krein - it sounds like this Delica would be perfect for a regrind.

gunmike1, have you found that touching up and maintaining the knives that you had Tom Krein regrind is pretty easy? Would I be able to maintain the performance with the Sharpmaker at 30 degrees, for example? I assume the included angle after the regrind is probably well under 30, and then I could sharpen with a microbevel at 30?

That would be no problem. I have several Krein specials, including a ZDP 189 Calypso Jr. It takes about 5 - 10 passes on a DMT red to completely regrind the edge bevel.

 

[matt321]

I'm practiced enough at sharpening 420HC folders and also Henckel kitchen knives. When I sharpened ZDP amd S30V for the first time, I noticed it was more difficult to finesse the final steps to bring the bevels together cleanly to reach pushcut levels easily obtained with 420HC. I presume the extra wear resistance is the culprit. The 420HC and the stones play together nicely. The ZDP seemed to tell the stones "You're not the boss-o-me!"