CNC Router Parts no longer offers the original 5-Start ACME nut.  They do however, sell a replacement nut. Get the new nut here.

The problem is that this new nut us a little larger than the original and if installed it will come in contact with the Y-beam.

To solve this problem you must add a 1/8 shim when assembling the Y-carriages.


Y-carriage Modifications

Chapter 5, Step 7

Here you are asked to attach the supports to the main frame components. You still do this but you need to place a 1/8" shim between the supports and the frame components.  The shim is made from piece of   1" x 2" x 1/8" steel. 


Use the supports as a guide to drill the two holes needed. You will need four shims for each carriage. That's eight shims total.



You can also make the shims out of aluminum.

Sandwich the shims in-between the supports and the main frame components when you assemble them in step 7.


Here is a PDF of the assembly process submitted by a customer.

Carrage Assembly


Y Motor Mount Changes

Chapter 9, Y Motor Mount Section

Since you have effectively moved the Y-carriage ACME nut over 1/8" towards the outside of each side of the CNC, You need to do the same with the motor mounting holes, bearing, and clearance holes. 

The following contains the new Y Motor Mount drawing files.

Y Motor Mount Drawings

While the X and Z axis don't require shims, you should make the following changes to the X and Z motor Mounts.

X Motor Mount Drawings

Z Motor Mount Drawings


More Information

For more information on the KRMx01 build, check out the following forum at CNCZone: