CNC machine spindle 2005


Well, I finally wore out the spindle on the IG-88 CNC mill. Those cheapo skate bearings that I've been using can't handle the constant high-speed abuse of a cnc mill. So, I decided to search around for better bearings and parts that would require minimal machine work to get a more reliable spindle. This is what I found.

I started off with a piece of 1.25"OD .825"ID cold rolled tubing from Online Metals. This stuff is just great. It has a wall of almost .2", which makes it real tough for a spindle housing. I then searched for high speed flanged bearings that had a .825"OD. It only took a few light passes on the lathe to get the ID of the tubing to the correct diameter to fit the bearings.


A 12" piece of this tubing was only about $10, so I cut the piece in half so I could make two spindles.


These bearings are almost a perfect fit for the tubing. With minimal work, the bearings snug right into tube.



A real nice high-speed spindle is on the way! I just might be on to something here.


Ready to machine the shaft!


Here you can see the parts layout. There really isn't that much too this thing. Sometimes simple is better! To make the shaft, I used a piece of 3/8" air hardened drill rod from Enco Tools.


Here you can see how a 1/8" solid carbide end mill looks next to the shaft. I bored the 1/8" hole to precision tolerances with a 1/8" carbide reamer. An allen set screw holds the end mil in place.


Only one threading operation is needed to hold the entire assembly together. I used a 3/8-24 Nylock nut to keep things in place.


The drive end of the spindle is quite simple. Just a nut, bearing, and pulley.


I picked up these bearings from They are part# FR6-ZZ and will cost you about $5 each.


On the work end, a simple e-clip arrangement keeps the shaft and bearings locked in place. The nut on the other end takes all of the slack out of the system and tightens the bearings against the housing.


How nice everything fits together! Of course this is the 5th spindle that I've made, so I've had my share of mistakes!


I stole the aluminum pulley from the old spindle, so I didn't have to make this part again.


A 1/8" solid carbide end mill installed and ready to test for runout.



All assembled and ready to fit up the motor mount!