Sweet Spot Index Calculator for Percussive Tools

[FortyTwoBlades]

Here's an open Google Doc where you can try making the calculations. I think I've got it setup right, but if you think something is amiss please let me know.

To use, find what you consider to be the sweet spot on your chopping tool by repeatedly striking a solid surface. Use a line of tape to mark the upper and lower boundaries of the sweet spot. Measure from the lower boundary of the sweet spot to the tip of the tool and enter the measurement in the column marked "⇞". Next, measure from the upper boundary of the sweet spot down to the point where the tool pivots in the hand. Enter this value in the column marked "⇟". Lastly, measure from the point of pivot all the way to the tip of the tool and enter this value in the column marked "L". Your sweet spot length ("▢"), Concentration Factor, Raw Score, and Diluted Score will all be calculated for you.

 

[KingKoma]

What is "the sweet spot"?

 

[FortyTwoBlades]

The sweet spot in this instance is the region of the object that, when struck during use, produces the least shock to the hand. In physics this is also referred to as the center of oscillation.

 

[screened porch]

Seems to me Sir Richard Burton in The Sword had some pendulum set-up to find the center of percussion on a sword. My eyes went glassy trying to read that too.

 

[KingKoma]

How does this relate to the area with the most potential to transmit force?

 

[FortyTwoBlades]

Seems to me Sir Richard Burton in The Sword had some pendulum set-up to find the center of percussion on a sword. My eyes went glassy trying to read that too.

Hahaha--I hear ya'. This stuff is just a wee bit technical. Fortunately that open Google spreadsheet I linked to will do all the calculations if you just plug in your upper and lower measurements and your L measure.

How does this relate to the area with the most potential to transmit force?

The region of greatest force transfer is often very close to the sweet spot, but also often not quite in the same position as it. However this is often academic since you're not going to practically end up using that spot as it will transfer more shock to the hand than the sweet spot, and so you'll be naturally disinclined to keep striking with that location. But the farther out the sweet spot is the more force can be generated, the larger it is the easier it will be to land a blow in the sweet spot, but the smaller the sweet spot is as a percentage of L usually the more concentrated the mass is at that region as well since concentrated mass "soaks up" vibration and influences nodal points of oscillation heavily.

 

[KingKoma]

However this is often academic since you're not going to practically end up using that spot as it will transfer more shock to the hand than the sweet spot, and so you'll be naturally disinclined to keep striking with that location

If I get enough penetration the vibrations should not be so severe as to make me not use the most effective part of the blade. If that should be the case then there would be something wrong with the tool. In my opinion, anyway. It would be helpful if you could show the difference between you chopping with a sub-optimal but comfortable part of the blade compared to the most effective part.

 

[FortyTwoBlades]

If I get enough penetration the vibrations should not be so severe as to make me not use the most effective part of the blade. If that should be the case then there would be something wrong with the tool. In my opinion, anyway. It would be helpful if you could show the difference between you chopping with a sub-optimal but comfortable part of the blade compared to the most effective part.

Check out these articles for information regarding that information in baseball bats--it's the percussive object in which the greatest amount of study has been done. Naturally cutting is not being performed with these and a two-handed grip usually employed as well as a number of other differences, but many of the same principles apply.

Remember, too, that my system is more of a descriptive one rather than a "hard quantitative science" one. Its purpose is to describe the feel and the potentially the ideal task-matching of the tool and the differences in those qualities from one tool to another.

 

[FortyTwoBlades]

Just added stats on the Tramontina 14" and 18" wood-handled Latin pattern models to the spreadsheet if you feel like giving them a gander. Remember--if you have any choppers you feel like trying this with you're able to enter your own info without needing to sign in or anything--just type away!