LengthLock

How it fits together

LengthLock, part by part

Scroll or tap a part. Press “See the 3D CAD design” to watch the model, built from our CAD, light each part up and show how it connects.

See the 3D CAD designShow the concept

Real-time 3D render · drag to rotate · final design may varySwipe sideways to rotate

1. 01

   The whole LengthLock

   A camera behind the bowling machine measures each ball's length, line and speed, then a servo turns the speed dial to hit the coach's target.

2. 02Brain

   Raspberry Pi 5 (SightCam)

   The brain: it runs the sightcam service program

3. 

   03

   Global shutter camera

   Films the ball at 60 fps with no rolling-shutter smear

   Raspberry Pi 5 (SightCam) · CSI-2 ribbon cable · 60 fps video

4. 

   04

   DialDrive controller

   Takes speed commands from the Pi and beeps before every move

   Raspberry Pi 5 (SightCam) · Wi-Fi (WebSocket) · Dial angle commands

5. 05

   Dial servo

   Turns the machine's speed knob to the commanded angle

   XIAO ESP32-C3 · PWM signal (1 GPIO) · Servo angle

6. 06

   6 V servo supply

   Steps the machine's 12 V battery down for the servo

   XIAO ESP32-C3 · Fused 12 V lead · 6 V servo power

7. 

   07

   NFC card reader

   Reads the coach key card and each batter's card

   XIAO ESP32-C3 · I²C (NetKey pod) · Card IDs

8. 

   08

   E-paper display

   Shows batter name, speed ceiling and helmet prompt in sunlight

   XIAO ESP32-C3 · SPI (NetKey pod) · Screen image

9. 09

   All connected

   7 key parts, one program, and your phone

How the parts connect

LengthLock, wired up

Every part, what links it to the brain, and how the data reaches your phone. A solid line is a cable; a dashed line is a radio link.

The program

What controls LengthLock

cam = Picamera2(); cam.start()
bg = cv2.createBackgroundSubtractorMOG2()
track = []
while True:
    frame = cam.capture_array()
    blob = find_ball(bg.apply(frame))          # OpenCV blob
    if blob:
        track.append(blob)
    elif track:
        bounce = fit_arcs(track)               # pre- and post-bounce arcs
        ball = to_ground(bounce, H)            # length, line, speed
        log_ball(ball); track.clear()
        if ctl.every(3):
            ws.send(json.dumps(ctl.next_set(ball, ceiling)))   # {"set_deg": ...}

To your phone

How the data reaches LengthLock coach page

Coach's phone browser

1. SightCam Pi
2. Wi-Fi access point · WebSocket
3. Coach's phone
4. Wi-Fi · WebSocket
5. DialDrive

Key specs

Targets for production units; they may change during development.

Pricing

Target prices: $349 SightCam, $129 per DialDrive, $449 LengthLock Kit, $79 NetKey pod, $529 Junior Nets Kit (SightCam, DialDrive, NetKey and 20 cards). Parts cost at quantity 1 is about $232 per SightCam, $60 per DialDrive and $51 per NetKey (est.).

Indicative launch pricing in USD, excluding taxes and shipping. Final pricing is confirmed before any balance is charged.

1. 27 Oct 2026, 16:40LatestCricket clubs need one product for the ground, not several kits and apps.

   • Folded into CricketOne: see https://iemilabs.com/products/cricketone/

   See it in 3DFull research and design

2. 27 Oct 2026, 12:20A batting-cage owner wants each machine lane to measure every swing, run without staff and give each hitter a pitch speed that suits their age. Posted rules keep under-16s out of the 70–75 mph cages (Fairfax County Park Authority), a used token and card control package for a facility was listed at $35,000 (JJ Amusements), and a programmable touchscreen machine costs $4,598.99 each (Anytime Baseball Supply). Our own two products for it cost $3,188 and $79 a month a lane.

   • Combined into CageLane (https://iemilabs.com/products/cagelane/); LengthLock itself is unchanged and stays the cricket-nets product

   See it in 3DFull research and design

3. 27 Oct 2026, 05:50A club with a league side and junior nets wants run-out and front-foot evidence for a lone umpire, an over-rate clock, junior spell limits and a smarter bowling machine. Today that is five separate kits, or a nets system from about GBP 2,200 (PitchVision) and sponsor-funded LED wickets (Wisden on Zing).

   • Combined into Cricket MatchKit (https://iemilabs.com/products/matchkit/); LengthLock itself is unchanged

   See it in 3DFull research and design

4. 26 Oct 2026, 06:49Clubs running junior nets now have to show that bowling machines are run only by experienced adults and never by under-18s (ECB Recreational Cricket Safety Regulations, December 2025 update). BOLA's own guidance adds short legs for under-12s and a playable speed for each player. A dial machine enforces and records none of this.

   • New CAD parts: NetKey case with a strap tunnel and charge port, and NetKey lid with a TAP HERE card dish, screen window and two buttons. All 19 bought parts fit-checked; each printed part is one solid
   • Junior Nets Mode: the speed dial only moves after an adult coach taps a coach card; each junior's card sets their speed limit, checked against the measured speed of every ball; a short-legs prompt for under-12s; the knob is turned down at the end of a session
   • Weekly session record for the club's welfare officer: who ran the machine, who batted, and their speeds. No video
   • Parts list +$51 per NetKey pod with 20 cards (est.); new $529 Junior Nets Kit (target)
   • Design notes: a dated Junior Nets section with 6 sources and a rules note; product page updated with summary, highlights, a junior nets use case, a new tier and 2 FAQs

   See it in 3DFull research and design

5. 25 Oct 2026, 00:26Manuals say ball consistency drives accuracy and residue builds on the wheels after about a dozen leather balls → the loop closes on measured length, so it corrects drift whatever the cause, and flags the wheels when the correction keeps growing

   • New design: 5 printed parts in code CAD, bought parts fit-checked
   • Market research, hardware list and use case written up
   • Design page and kit render published
   • Product page added

   See it in 3DFull research and design