Calibrate your screen
So cracks are shown at their true real-world size, tell the game how many pixels equal one millimetre on this screen. Pick a method, match a real object against the screen, then save.
Hold a standard credit/ID card flat against the screen in portrait (tall) orientation and drag the slider until the outline exactly matches the card (54 × 85.6 mm).
Hold a ruler along the line below. Adjust the slider until the line spans the length you set here, then read it off your physical ruler to confirm.
Which cam fits this crack?
Rack: change
Choose your rack
Pick the cam set you're learning. Cracks and gear will match its real sizes; your choice is remembered on this device.
reference
Bars are drawn to true scale when your screen is calibrated. Notice how neighbouring sizes overlap — that overlap is where placement judgement matters.