Cut Lines

Along with the wide variety of closures, (covered in the previous post) there is also a diversity of door profiles. These are determined by the door's cut lines, which establish its perimeter. Below we'll take a look at how these cut lines are made for different kinds of closures.

Conventional Hinging: The cut lines need to be adjacent to the hinge axis line so that the doors can swing open freely. The cut lines must also be sympathetic to the rear view, side surface contour. In other words, cut lines should look natural from all angles. They should yield to the exterior shape of the car. The leading edge of the doors will rotate inwards, towards the car, while the door swings outward.

Toyota Yaris

Unconventional Hinging: There are many kinds of unconventional hinging, but consider gull-wing doors. With the hinge axis on the roof, there is a lot of freedom for the side cut lines.

Pagani Huayra

Frame-less, Conventionally Hinged Two-Doors: The front cut lines are still restricted by the hinge axis line, and the rear cut lines usually curve rearward, beyond the rear edge of the glass. This provides room for the latching mechanism and the glass to slide into the door.

Mini Cooper (cut line highlighted)

Exposed Structures: Sometimes the door cut lines will yield to the body structure, which displays strength in the exterior design.

Smart Fortwo

Large Two Doors: Large two-door cars need long doors to maintain good proportions. However, door length should not exceed 1400mm to reduce stress on the hinges and minimize the outward swing.

Dodge Challenger

Rearward A-pillars: The A-pillar lower is the structure behind the front wheels used to mount the front door hinges. The A pillar upper tracks around the windshield and supports the roof. In cars like the one shown below, with a long hood profile, the A-pillar upper is pulled back to improve cornering visibility. The A-pillar lower cut lines are moved forward to improve foot swing when entering/exiting.

Dodge Viper SRT

Commercial Vehicles: The driver is typically pushed forward to maximize the area for cargo or occupants. Thanks to the high floor structure, there does not need to be a lot of horizontal leg room. In other words, the driver's H-point is high relative to the pedals. To improve foot swing for ingress/egress, the front cut line tracks around the wheelhouse. The cut line for the sliding door is completely straight, which is not possible for a conventionally hinged door.

Ford Sprinter

Cab Forward: This is essentially the opposite of Rearward A-pillars. The upper A-pillar is pulled forward, beyond the lower A-pillar. In order to fall behind the front wheelhouse structure, the front door cut line passes through the upper A-pillar as it approaches the roof.

Honda Concept Car

Forward Control: This is when the A-pillar is at the very front of the vehicle. This is not common today because it has frontal impact issues, compromising driver safety. This setup forces the driver's feet between the A-pillar and the front wheelhouse structure. To accommodate this, the door's front cut line is dramatically different.

VW Type 2

Thanks for reading!