Intro

Hi Fellow Slingshooters,

I started slingshooting 1 year ago, and I have watched many videos, I have read many forum posts, etc. Many, many reviews, opinions, instructions, suggestions, recommendations, and so few data. I am an engineer of industrial measurements, so I miss those facts. 

In this blog I will publish my simple and cheap, but technically correct tests, which - I hope - will help the slingshooting community to develop. My posts will be text based, not videos. Why? This is much easier, faster and cheaper to make. My lab equipment is very humble, but enables me to perform quite useful tests. In my tests I will use SI (metric) units. In the numbers I will use decimal points.

My equipment list today:
- an electronic fishing scale (0...20 kg, accuracy: +/- 2 gram)
- a measuring tape (0...5 meter, Class I, max error on 1 meter is 0.5mm)
- a digital caliper (0...170mm, accuracy: +/- 0.05mm))

Ordered equipment (arrives in January)
- a shooting speedmeter (cronograph, 0...1000m/sec, accuracy 0.5% of the display value)
- a laser rangefinder (0...1000 meter, accuracy +/- 1 meter)

I repeat: In this blog you will not find any opinions. Just the test descriptions, the measured values, and the raw conclusions. 

Popular posts from this blog

Tapered flat band max elongation

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  Precise is one of the market leading slingshot band manufacturers. In their website, at the product description they write: "5 to 6 times the super tensile strength, safe and stable." We can consider this, 500%...600% as the recommended maximal safe elongation range.  Tapered bands are wider at the fork end and narrower at the pouch end, so they are stronger at the fork end, weaker at the pouch end. When we pull the band, the elongation will be higher at the pouch end. How much is the TOTAL elongation, when the pouch end elongation is in the middle of the factory recommended range? Test description I cut a band from 0.6mm Precise elastic, 18/12mm taper. 180mm long. I fix its narrow end to the bench. I draw a thin line 1cm far from the fixing block, and another line at 16cm.  Then I pull the wide end until the pouch end elongation is 550%, and read the total elongation. Then I pull further the wide end, until the pouch end elongation is 600% (safety limit). Then I ...
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How much material is in the elastic tube?

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It is obvious: Thicker rubber generates bigger force. If you use flat bands, it is easy to calculate the area of the flat band (see my drawing) area=width*thickness. (If the flat band is tapered, you have to use the width at the middle.) If you would like to pick an elastic tube, which has similar strength, you have to calculate the area of the cross section of the tube. Elementary school geometry. It is actually the difference of a large circle and a small circle. You can find the formula in the drawing. For example, if you pick 1632 tube size (1.6mm inner diameter, 3.2mm outer diameter) then the area of the cross section is cca 6 mm^2 (square mm). If you use 0.5mm thick flat band, then a 12mm wide one will be similarily strong. Similarily. This is a very complex issue in reality, it is easier to measure. You will need a fishers' digital scale for that. I think, all the serious slingshooters must have one.
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Draw force - not weight

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 One more post about basics. In many videos, comments we can see/hear the expression: Draw weight. This is incorrect. The correct one is: draw force. Please use this. What is force? In physics, a force is an effect that causes a body to accelerate or change state. Force has direction, which can be any direction. Up, down, left, right, anything. What is weight? A special force. Weight is the force, the Earth is pulling the bodies down. Yes, weight is always made by gravitation, and always pointing downwards.  When we are talking about the strength of a slingshot band, then we are talking about the force we need to hold it, the same force which will accelerate the ball. It is very useful to know this force, to find our favorite setup. We can easily measure this force, by a fishers' scale. This device actually measures force, but fishers use it to measure the mass of a fish, so usually we can see mass measuring units (kg, lbs) on its display. But the measuring unit of force is Ne...
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