What part is this? Help!

[WarrenW]

I'm studying alot of machines built by users here on the site and learning about the different parts. Below is a picture of Joe's cnc showing the leadscrew. What parts are used here to move the gantry? I ordered some acme 1/2-10 threaded rods today but need to know what parts I need for the gantry? Is there a nut in there or did he thread the plastic? What do most people do for this part? And I have seen on the end they put the rod in a bearing.

Thanks

[widgitmaster]

This looks like the lower x-axis slide and screw, with the risers for the y-axis, and the z-axis is barely visable.
Eric

[ger21]

The plastic is the nut. What most of us do is make a tap out of a scrap piece of the acme rod.

The nut is bolted to the gantry, the stepper turns the screw, which moves the nut, and the attached gantry. The screw needs to be mounted in some type of bearing to take the load. The load should not be caried by the motor.