Tis the season and we all want to cut some pumpkins. And I’m here to answer all your questions about it.
Are Pumpkins Easy or Hard to Cut?
Yes!
One of the main reasons tatami mats are used for training and competition is that they are a very consistent medium which gives you good feedback. Pumpkins are basically the polar opposite.
Most pumpkins are very easy to cut, however some do offer some non-trivial resistance. I have actually come across a pumpkin which was considerably more difficult to cut than tatami mats.
What Makes a Pumpkin Hard to Cut?
A pumpkin offers resistance to the blade in a way fundamentally different from most cutting targets. The pumpkin itself offers very little resistance to being cut, but it does offer drag on the side of your blade. This is why you can cut through a pumpkin with a blunt sword without much difficulty.
What is the biggest impediment to a cut is the thickness of the blade, and far more importantly, the rigidity of the pumpkin itself. I’ve written about the resistance of the target binding on the blade before, so for a more formal description you can check out SwordSTEM: Sword cutting… and how the target pushes back!
What Makes a Pumpkin More Rigid?
1) Ripeness. You are all familiar with how soft and saggy a pumpkin gets after you are too busy and leave it out after halloween for a month few days. It isn’t a great shock to learn that as a pumpkin softens up it becomes significantly easier to cut.
2) Size. The smaller a pumpkin will be more rigid, while the bigger pumpkin will deform more easily. This deformation allows space for the blade to pass, allowing the sword to cut through with little resistance.
3) Wall thickness. Different pumpkins have different wall thicknesses, and you have no idea until you cut it open.
The aforementioned “pumpkin tougher than tatami” was a small pumpkin (smaller than a soccer ball) which was just about all skin and warts. The person cutting it got a real surprise when they were expecting to pick it apart with relatively little effort.
Because most of the difficulty of a pumpkin is difficult to predict they make marginal training tools, and are almost useless for evaluation purposes. Things like ripeness and wall thickness are very unclear until after you cut, though in extreme cases you can feel how soft a pumpkin is as soon as you pick it up. (Yuck!)
Can I Learn Anything From Pumpkins?
Yes. But you just have to be careful. If you are picking up stuff about your edge alignment by examining the cutting plane you can learn something, but you can’t use the pumpkins as verification. Most pumpkins will be very easy to cut through, and you can use very poor form. If you are lucky you can get some very stiff pumpkins and get good feedback, but unless you are familiar with cutting you won’t know what you are looking at. And if you are that familiar you don’t need to learn about the utility of the feedback from this article.
Probably the best use is to work on keeping long cutting planes. Putting two pumpkins next to each other and see how straight a line you can cut through. Or how long you can maintain a cutting plane for. (Remember, failing to generate a good cutting plane is one of the major errors in cutting. SwordSTUFF: You Can’t Fix Your Edge Alignment)
But even if you don’t learn anything by cutting pumpkins it is a great time and I encourage you to all take advantage. Be safe and have fun!
All my pictures were taken from this amusing video. Go watch it: