In a direct drive saw, the motor and the blade are both mounted to a center shaft. When the motor spins, the blade spins along with it. In a wormdrive saw, the motor armature is in line with the blade. The transverse mounted gear system doesn’t have a direct pull. A 4-to-1 gear ratio slows the motor power and gives the tool a lot of extra torque. Be aware that when the trigger is pulled on a worm drive saw, the transverse gearing causes the tool to jerk.

The way the motor is mounted means a worm drive saw has a thinner profile than a direct drive saw. That makes the worm drive saw small enough to get into some tight spaces. Another advantage of the worm drive saw is the way it hangs straight down when held. (This is one reason that a lot of roofers used wormdrive saws. It is easy for them the cut through rafter tails while they are on the roof and let the saw drop straight down.) Even though a wormdrive is heavier, a direct drive saw can be off-balance in the same position because of the weight of the motor.

A direct drive circular saw can be awkward for a right-handed person because you have to lean over to the far side of the saw to see where the blade is cutting. On a wormdrive saw, the blade is mounted on the left so that you can see the blade.