Steel i3 Prusa from Createc in Spain

[3DPBuser]

This corresponds to Createc's video for the Z axis:

https://www.youtube.com/watch?v=SjYbHEGWtPI

Remember you are using the black steel X pieces; not the blue plastic ones in the video. Other than that, the main thing I can stress is to be prepared to spend some time positioning the X carriage onto the X smooth rods, and the brass nut in the X carriage, so that there is absolutely no binding of the threaded rods as the Z moves up and down.

This binding comes about because of the very slight tilting of the brass nut that is press-fit into the X carriage. Although you will never have to worry about warped wood, cracked plastic, or the higher thermal expansion of aluminum, the steel X carriage is a challenge to put together without binding because there are no screw adjustments for the Z brass nut; the press-fit is permanent and non-changing. But it must be perfect, and this takes some time to adjust.

So one thing to do differently from the video is to leave the threaded rods loose for a while (not connected to the motor), and experiment with the brass nut and X carriage placement. Then connect to the motors and test the position by hand-rotating the Z motors and watching the top of the threaded rod to see if it stays in the center of the hole in the top plate. It needs to stay dead center to avoid binding.

Also, raise one of the Z sides up more than the other, and then vise versa; if they start binding at about the same tilt, this is good. However if one direction starts binding way sooner than the other direction, then that tells you the brass nut is tilted.

The brass nut should really have been put in perfectly before assembling the X carriage, but if it needs adjustment (you cannot use a hammer now) you will have to use large pliers to very slightly tilt it. Then try the threaded rod rotation test, and the vertical Z test, and the tilted Z test again. Eventually it will be smooth, and permanent, because there is nothing to warp, expand, or crack.