Imperial Dragon bowie and hunter/utility : Zubeng

C

Cliff Stamp

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Oct 5, 1998
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Website (flash heavy) :

http://zubeng.rghknives.com.tw/

Ref :

http://www.bladeforums.com/forums/showthread.php?t=410637

The knives :



These are high carbon steel blades forged in a very special way, see website for details, which claim to produce solid toughness at a very high hardness. A certified materials lab test shows a consistent edge hardness of 66.5-67.5 HRC.

The bowie weighs 590 grams with static and dynamic balance points of 4.5/10.5 cm in front of the index finger in the grip. The blade is 25 cm long, the overall length is 38 cm. The blade is 5.0 cm wide with a full flat grind which tapers to an edge which is 0.055" thick with a light convex grind of 13/15 degrees.

The hunter/utility blade is 190 g, and has a full distal taper from 0.4 cm to 0.1 cm before the tip. The blade is 10 cm long with an overall length of 20.5 cm. It also has a full flat grind on a 3.4 cm wide blade. The edge is 0.035" thick and ground at 15/17 degrees per side.

These are evaluation pieces so they have cosmetic issues and the edge is only rough sharpened. The should be interesting to work with.

-Cliff
 
The hunter/utility sounds 4-10 times thicker than it needs to be assuming the rest of the advertizing is true.
 
At the edge yes, pretty standard for that type of knife in thickness/angle but I will be adjusting it. As noted these are just rough sharpened so these are not representative of the knives you buy in anything other than the performance of the steel. The conversation was basically "Here are the knives, adjust the handle/blade as you think is best and see how the steel performs." What I found really amusing, well it is funny to me anyway, was "... do whatever you think a hard use knife should be able to do." as they were interested in showing that the steel isn't as brittle as many would expect given the hardness. It has been a long time since someone has asked me to do that. Now all I need to do is find a 10 000 pieces length of hemp rope.

-Cliff
 
I'm very interested in seeing how they hold up. Can't wait to hear. Nice that they gave you plenty of latitude in terms of specific test procedures.

...with static and dynamic balance points of 4.5/10.5 cm in front of the index finger in the grip.
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I find it somewhat interesting how they can promote the knives and charge good prices for them (for $800 you could find plenty of good smiths to make a good working knife) based entirely on some magical steel, yet totally miss (IMHO) other important aspects of performance. With a distal rotational/impact node less than halfway down the blade,... well... I think dynamic use will suffer.
 
Cliff I am very interested in the testing of these knives. Especially with such a high rockwell. The knives seem to be priced very high so we'll see if they live up to the hype he puts on the pages.
 
small blade has an awfully funky profile, wonder why the point wasn't dropped more, especially with the taper and grind
 
I am looking forward to your review on this Cliff, im impressed with the Rc hardness and wonder if they are brittle, im also impressed with them telling YOU to use 'em hard. thats pretty scary!
 
I sharpened the large one, just rough, it shaved, push cut newsprint, etc. , but really hard steel will basically do this pretty much effortlessly and can be taken much higher. However I didn't want to a lot of effort into adjusting the edge angle as the steel was unknown so I just put a working edge on it with the existing edge grind. I would be very confident it is as hard as claimed as it acts just like other knives I have which have tested that hard.



This is 54 sections of wood, 1006 chops, including work through knots. I benchmarked it roughly against the Wildlife hatchet at 71 (2) % in terms fo number of chops which isn't bad considering I was still getting a feel for it and the edge isn't optomized in angle. There was no damage to the edge under 10X magnification either from the side or even straight down. There was almost no distortion or wave to the edge.



The large piece in front was the baton. The wood was sectioned at random placement, which is a stupid way to do it because you end up having to cut through knots and it takes *way* more effort, but I wanted to check a worse case senario for low light conditions or an inexperienced user who didn't know how to place the knife to work with knots. The edge was still unchanged under 10 times magnification and still slices newsprint readily.

I am going to see if I can get a few short videos to show that the knife isn't being used lightly. It was cutting the sticks to length in 10-20 chops and those were full force impacts (while sitting) with the round for the splitting. There was some feedback on the far tip impacts while splitting which would be expected as the dynamic balance is close to the hand. However, from memory, it wasn't as strong as other knives which may be due to the differential hardening. I need to check this with a side by side comparison.

I am now satisfied that the knife is worth the time to optomize the edge profile and give it the sharpness it deserves. I'll then likely do some stock edge retention work and then do some actual wood work as I have about 10 truckloads of sticks that need to be limbed out anyway. I'll also regrind the smaller one and run it against some other knives.

the possum said:
Nice that they gave you plenty of latitude in terms of specific test procedures.
Click to expand...

In general I have always found that people with high quality products don't have much concern with how they are evaluated (as long as it is unbaised) because there is confidence in the performance. Hype however tends to be really restrictive because it is known that it won't hold in any significant evaluation.

With a distal rotational/impact node less than halfway down the blade,... well... I think dynamic use will suffer.
Click to expand...

For a lot of people this type of balance is desired which is why many knives have index finger static balance points and no mention of dynamic balance. I would also prefer a dynamic balance further down the blade, take all that stock in the handle and put it at the end of the handle to start.

barrabas74 said:
The knives seem to be priced very high so we'll see if they live up to the hype he puts on the pages.
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They are priced very high, however they are also handmade which even includes the steel which is refined from iron ore by the maker in his workshop.

hardheart said:
small blade has an awfully funky profile, wonder why the point wasn't dropped more, especially with the taper and grind
Click to expand...

This isn't on the webpage, I think it is just an evaluation prototype. I was told to regrind the blade as desired. This is just a small piece which is easier to use as a benchmark for the steel against shorter knives than the large bowie.

darkestthicket said:
... im also impressed with them telling YOU to use 'em hard.
Click to expand...

Yeah, interesting times ahead.

ghost squire said:
When are you going to invent an edge retention testing machine?
Click to expand...

My parents invented one some time ago, it sometimes get distracted as it is highly argumentative and exceptionally unstable and antisocial around hype, however is pretty functional when it decides to do some actual work.

-Cliff
 
Cliff Stamp said:
//edge-testing machine//
My parents invented one some time ago, it sometimes get distracted as it is highly argumentative and exceptionally unstable and antisocial around hype, however is pretty functional when it decides to do some actual work.
Click to expand...

Did that machine break your Basic-7 and Howling Rat and take your Spyderco Atlantic Salt?
 
I resharpened the Zubeng on a 1" belt sander, made the bevel much wider, it is now 0.073" thick at the back and a massive 0.205" wide. I repeated the wood chopping, 48 sections cut each with it and the Bruks Wildlife. 972 chops with the bowie in total and at the edge it still wanted to push cut newsprint right next to the hand though was catchy, sliced it readily. Under magnification there was one spot of damage was was 0.1x1 mm. Plus one of the logs I cut was full of dirt and I chopped into it accidently.

I was however kind of surprised the relative chopping ability was not raised as it was still 70 (2) % which also makes me wonder if I have not thinned out the Bruks significantly since I got it, I wish I had done a full edge measurement initially. Anyway, I measured the edge on the bowie and found the reason that the performance didn't change significantly is that I mainly reduced the shoulder, the edge is still 15 degrees per side in the last 0.025".

thombrogan said:
Did that machine break your Basic-7 and Howling Rat and take your Spyderco Atlantic Salt?
Click to expand...

No, that's the second generation model which only has one speed (overdrive) and doesn't have an off switch.

-Cliff
 
Here is a very short video just to show the typical type of chopping impacts :

http://s7.photobucket.com/albums/y2...dragon/?action=view&current=zubeng_chop_I.flv

This is a fairly sloppy cut as I was doing it statically with maximum force, I normally would cut much faster and significantly lighter. I also don't tend to pry the chips out like that, again just a worst case senario to load the edge. All the chopped wood in the background was cut with this knife and the Bruks.

-Cliff
 
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