Lead or Lead?

There exists a VEX part called a lead screw. Is that a lead (opposite of follow) screw, or a lead (Pb) screw?

Considering the Advanced Mechanics and Motion Kit is almost entirely plastic, and the lead screws included therein are 100% plastic, I would have to guess the former.

That’d be my guess, too, but there’s definitely plumbing that isn’t lead, so I wasn’t sure.

Here’s a picture of the entire lead screw system just to be clear:

(Source: RobotMesh)

Right, I know.

My point is that the word “plumbing”, iirc, is derived from “plumbum”, or lead. But today there exists plumbing that is not lead. So I wasn’t certain if this type of part was originally made from lead for one reason or another in the real world, giving it its name.

On second thought, this may be a question for Google.

EDIT: It’s definitely the opposite of follow.

I understand now what you were getting at.

Opposite of follow.

It is a standard type of linear actuator. The term comes from the lead of the thread, as defined here;

It also can be called a worm gear

If you called it that, you’d be wrong. A lead screw and a worm gear have different thread profiles and serve different purposes. A worm gear is made to mesh with special pinion gears. Lead screws mesh with special followers, either a lead screw nut or a split nut.

Worm gears are designed for minimum frictional losses. Lead screws are designed for high precision. Lead screw profiles do a very poor job of transmitting power. Worm gears are designed to transmit power.

Here’s a link to the VEX Advanced Mechanics and Motion Kit. It contains both worm gears and a lead screw, which is shipped in segments.

Note how the parts are listed:

(2) Hand Crank
(1) Lead Screw Nut
(4) Lead Screw Segment
(2) Lead Screw Mounting Bracket
(2) 16-tooth Bevel Gear
(2) 32-tooth Bevel Gear
(4) Worm Wheel
(4) Worm Gear
(2) Drop Off Cam
(2) Cam Follower
(2) Cam Follower Mounting Bracket
(2) Universal Joint

Here’s a link to a video of the VEX Lead screw being demonstrated.

Here’s a link to a video demonstrating the worm gear driving a worm wheel.

[edited to correct two typos. I have no idea how many remain, because if I did, I’d fix them.]