free hanging manila rope test

[pahl]

Hi,
Ok, I have been getting into sharpening the last few days, as you can tell from my other post
I have been testing the knife edge mostly by cutting paper and using the finger nail test.
Now that I have gone through all my knife (only have kitchen knives and lm wave)I was sitting here with nothing much to do today.
Been reading through the forums and some posting on using rope to test the sharpness of the blade.
So I went to the store to get some rope to test my knives.
I don't do much with rope and I have not bought any rope in a long time for anything. There sure was alot of differant rope to choose from.
Well I got 6 feet of manila rope and 6 feet of poly rope both in 3/8 inch.
The sign said "do not cut the rope yourself". Dam I thought, I got my leatherman wave on my side with a razor sharp edge on it and all this rope in front of me and I can't cut any of it!
Ok so i get some guy working there and he cuts the poly stuff with a hot blade thing. The he goes and get a box cutter to cut the manila rope. He worked the box cutter back and forth for about 30 seconds and could not get through it. I took out my wave and said lets try this one
Cut through it without even trying.
So I pay for the rope and head back to the house. Cut through the rope with all the knives i sharpened without any problem.
Now I hold the rope up with one and and try the free hanging rope test. Tested three knives and the all just about cut through, but did not cut clean through.
I was kind of disapointed. The I remembered one of the kitchen knives I put a double edge on.
Took the double edge knive and gave it the free hanging rope test. The end of the rope fell to the floor. Cut clean through the rope with the first swing.
I thought now thats sharp or is it?
Thought my other knives were sharp till I tested the one with the double edge.

Sorry this story got so long

Do you use rope to test your blades?
What kind and size of rope do you use?

A guy can go through alot of good rope fast with a sharp knife

JP

 

[Keith Montgomery]

No I do not use rope to test how sharp my knives are. If I did I would just use one strand from a 1" Manilla rope and just try a few cuts with the rope laying on a cutting board or work bench. Rope is too darn expensive to test for sharpness by cutting through a 1" hanging rope.

It is also not just how sharp the knife is, but the geometry of the blade is important as well. Knives that do well on cutting hanging rope will not usually be very good at other types of cutting. The blades are quite often very hard, quite thin and not very tough. There is also a lot of skill involved in knowing how to swing the knife to make a proper cut.

So now, to put this all in a nutshell, I do not think that hanging rope cutting is a very practical way to test the sharpness of a knife. If you enjoy doing it for the fun, then go right ahead and cut to your hearts content. Maybe someday you will get really good at it and win some cutting contests.

 

[kogatana]

The manila rope test is an intriguing exercise and a fair test. Personally, I think that one should test a blade on the application in which it is intended to be used. I can't help thinking about what Bruce Lee once said on celluloid 30 years ago: "...booooaaaards don't hit back." I think it applies to blades on hemp, too.

 

[Cliff Stamp]

KWM :

I do not think that hanging rope cutting is a very practical way to test the sharpness of a knife.

If you stick to one knife, you can judge its sharpness by the least amount of rope you can hang and still cut, or the closer to the end you can cut it as in both cases you are reducing the tension. To examine the influence that this has, tie a weight to the end of the rope and see how easy it is to cut. You can also look at the amount of force it takes to push cut or slice through the rope by cutting on a scale. However just as you noted, this isn't the most practial way, as you can do the same thing with thread, and a cheap roll of thread is like fifty cents and will last you for thousands and thousands of sharpness tests. However, while there are better tests for sharpness, cutting hemp rope can give you useful information about the cutting ability in general and edge retention.

-Cliff