Important! This page is only provided for those that purchased one of the first workbooks and the original one piece ACME nuts.

This upgrade is a no brainier. The new ACME nut assembly is only about $16 more and its aluminum mount is easier to install and does not warp under excess pressure. The steel anti backlash spring wont wear out. You can purchase the new nut from CNCRouterParts.

If you have not yet built your Z-axis, I recommend installing this one so you wont have to do the upgrade later.


  1. Remove Z-beam
  2. Remove single piece ACME Nut
  3. Add thread lock to cap screws
  4. Install new ACME Nut Assembly (without dowel insert)
  5. Tighten screws with 1/4" Allen wrench
  6. Re-install Z-beam


See installation here: