BP1 Racquet Balance Device

Description

The Briffidi BP1 brings modern balance point measurement to everyone. No more balancing. No more eyeballing the measurement. No bulky contraption. No expensive machine. Just set the weight of the racquet and the weight of the loaded BP1, and the balance point will be displayed.

Easy to Setup and Use

Setup

1. Install the companion app (available free in the Apple App Store and Google Play for iOS 14+ and Android 8.1+).
2. Separate the two halves of the BP1, align the pins, and press the halves together.
3. Fold out the support arms.
4. Place the BP1 on a flat surface next to your scale and adjust the handle support height until the adjuster surface (not the ball) just touches the scale platform.
5. Place the handle end support ball on the scale platform and set the empty BP1 weight in the app.

Use

1. Measure and set the weight of the racquet.
2. Place the racquet on the BP1 and set the weight of the loaded BP1.
3. The balance point will be displayed. Double-tapping the result will copy it to the clipboard.

Store

1. Fold in the support arms.
2. If a smaller size is desired, pull the two halves of the BP1 straight apart, place the head end of the BP1 on top of the scale end with the offset support extending through the opening closest to the joint, and press together.

Tennis, Pickleball, and More

The BP1 works with a wide range of racquets and paddles. The balance point must be no more than 37.3 cm (14.7″) from the end of the handle, and the overall length must be at least 36.7 cm (14.5″).

Scale Required

You will need a scale to measure the racquet and BP1. The BP1 adjusts for scales with a platform height of 12 to 22 mm (0.47 to 0.86″). Scales with higher platforms can be used, but the other end of the BP1 must be raised with a suitable object (for example, a book). A scale resolution of 0.1 grams or better is recommended. If you need a scale, this one and others like it have a suitable platform height, are inexpensive, and work well.

Video

Questions & Answers

Q: How is the balance point calculated?

A: The BP1 uses static moment analysis to determine the balance point. The locations of ball supports on each end of the BP1 are known relative to the reference surface that locates the end of the racquet. Together with the weight of the racquet and the weight of the BP1, the sum of moments can be set to zero and the location of the racquet balance point can be determined. The equation below can be used to calculate the balance point without the app.

x_b: location of the balance point (cm)
x_e: location of head support (37.02 cm)
x_a: location of handle support (-4.00 cm)
w_b: weight of loaded BP1 end (g)
w_e: weight of empty BP1 end (g)
w_r: weight of racquet (g)

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Q: Can the app show the balance in points head-heavy or head-light?

A: Yes, points HH/HL can be displayed by enabling it from the Settings page. Be default, the value is based on a standard tennis racquet length of 27″, but the length can be adjusted in ¼” increments.

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Q: How accurate and precise is the BP1?

A: Accuracy and precision depend on the scale being used and on the racquet or paddle being measured. For a tennis racquet with a mass of 320 g and balance point of 32.5 cm, using a scale with accuracy of ±0.2 g, an RMS error analysis results in balance point accuracy of ±0.06 cm. The dominant source of error is the distance from the reference surface to the head support location (±0.05 cm for this analysis). Precision will be much better than this, as the support location will not vary by ±0.05 cm.

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Q: My scale only has 1 g resolution. Is that good enough?

A: Perhaps. To improve precision, set the empty BP1 weight in the app to zero and use the tare function of your scale to zero out the empty BP1 weight. Normally, the app does this for you by subtracting the empty weight from the loaded weight, but with only 1 g resolution, the rounding from two measurements becomes significant. For a typical tennis racquet with a scale accurate to ±1.5 g, the balance point result will still be accurate to ±0.2 cm.

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Q: How long will the snap clips of the BP1 last?

A: I cycled a sample with a glaring print defect (poor first layer adhesion that I would never ship) in one of the snap clips until failure. The defective snap clip lasted 805 cycles before it broke. The non-defective snap clip was still functioning perfectly after 1000 cycles. Unless you’re using the BP1 as a fidget toy (I sometimes did, but that cycle testing may have cured me.), the snap clips should last for years.

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Q: The support locations are adjustable in the app. Why would I adjust them?

A: There is always some variability in manufacturing. The balance point calculation is sensitive to the value used for the head support location. It’s not very sensitive to the handle support location. In my testing, I’ve measured a range of ±0.025 cm for the head support location. If, for whatever reason, you’re trying to measure balance point with very high accuracy, you can adjust the head support location based on your own measurements. In printing, I create small marks on the bottom surface of the BP1 that are aligned with the handle reference surface and the head supports.