15 Minute Spindle Lock Upgrade for Your X2 MiniMill

Shanghai SIEG Machinery Company, an Asian machine manufacturer, makes a small, bench-top milling machine known as the “SIEG X2” or simply “X2”. The X2 is typically privately branded and is available around world from many sources. In the U.S. for example, the basic unit is distributed and sold through Harbor Freight, Northern Tools, Grizzly, Little Machine Shop, and many others. These little milling machines can run on 110 VAC power (U.S. models), and are typically available in the $550-$950 range. The base design has been around for some time has under gone changes and updates over the years.

Owners of these units have also come up with many changes and updates to improve performance and add new features. Many, as have I, perform CNC conversions to the X2 to explore that interesting technology.

This Instructable adds a simple change that replaces the standard hand-held SPINDLE LOCK PIN with a improved spindle locking mechanism. While designed for the standard, gear driven mill, the basic idea should be adaptable to belt driven models as well.

When changing mill-bits, it is necessary to loosen a draw-bar retention bolt that goes down the center of the spindle. In the standard X2 mill, the operator must hand insert the SPINDLE LOCK PIN pin into the mill. The SPINDLE LOCK PIN keeps the spindle from turning while you are loosening/tightening the tool retention bolt.

There are a number of designs out on the net, some of which are available for purchase as upgrade kits. All of these designs replace the separate, HAND-HELD LOCK-PIN, with a simple spring loaded pin that is permanently mounted to the mill. Just ‘push the button’ to engage the lock pin.

Unfortunately, all of the designs I found either require the hobbyist to machine several custom parts (usually requiring a metal lathe to turn a new locking pin) or an investment of $25 to $50 for a “ready to install kit”. Even the kits usually require drilling and tapping new mounting holes into the castings of the mill.

I’ve come up with a simple spring loaded spindle lock that is made from a readily available hardware that can be made in 15-20 minutes of shop time. The new lock assembly features a simple friction fit installation with no drilling or taping of the mill needed. Lastly, it's low cost, simple, and 'fully reversible". If you don’t like it, or it doesn’t meet your needs, it’s easy to remove so you can go back to the standard, hand-held spindle locking pin solution.

This isn’t a major, “save the world” invention, but some of you might find its simplicity useful or perhaps be able to use these ideas as a launch point for your own adaptations.

Use your milling machine with a 1/8" end-mill to put a slot in the side of the plastic flange bearing.

I choose a 2" long shoulder bolt so it would easily slide back and forth inside of the bearing sleeve,

As noted, verify there is no interference with the spindle when the lock is not depressed. Be sure there is enough spring tension to be sure there is no chance for accidental engagement while the mill motor is running.