Attachment 438998


The picture above shows how my X-axis ballscrew was being lubricated as delivered from the factory. I thought that the oil being merely dripped on the ballscrew outside of the ballscrew nut was not a good idea. And the Y-axis and Z-axis had their lube lines attached to the ballscrew nut. The problem for the factory (and me) was that there is simply no room to attach a lube line to the X-axis ballscrew nut.

I decided that the solution was to do some milling on the ballscrew nut in order to make room for a lube line. You know how they say that the road to hell is paved with good intentions? Or that no good deed goes unpunished? I was about to learn these two lessons the hard way.

I first had to remove the X-axis ballscrew nut from the ballscrew mount. The next step was to remove the ballscrew nut from the ballscrew. So i made the tool below so I could safely remove the ballnut from the ballscrew without losing any of the little balls. The ballscrew removal tool is simply a scrap piece of aluminum turned to a diameter of 0.652" on the right side (ignore the left side as that was for a different project).

Attachment 438996


The ballscrew removal tool worked wonderfully and I successfully was able to remove the ballscrew from the ballscrew nut. Unfortunately, somewhat later and due only to my clumsiness, I accidentally allowed the ballscrew removal tool to slip out of the ballscrew nut and let loose the all the little balls. Boy, do they bounce good. The silver lining is that I was able to thoroughly clean the inside of the ballscrew nut, and also was able to learn how to reinstall the wayward balls. The secret, of course, is grease. And a good set of magnifying lenses.

I set to the task of milling the ballscrew nut and learned very quickly that the nut is hardened steel. So I was forced to pull out the Dremel and I set to work grinding on the nut. This was a slow process and after a lot of work, this is what I ended up with. There is almost no clearance under my table, so the groove that I ground in the nut is deep enough for a 3/32" diameter tube to fit flush.

Attachment 438978


The next step was to machine a custom oil fitting out of a M6x1.0 bolt. The bolt head was mostly cut away for clearance from the table, and then milled to length. Then I drilled a 3/32" hole in the center from the bottom, and then another 3/32" hole in the side.

Attachment 438980


And here is the new oil fitting with the 3/32" aluminum tubing test fitted.

Attachment 438984


Here is the new oil line to the ballscrew nut. I used some 4mm tubing that John had sent me and I opened up one end with a 3/32" drill for about a 1/4" or so. The 3/32" tubing fits snugly inside the 4mm tubing.

Attachment 438990


Even with all of that work, the amount of clearance is still very tight.

Attachment 438992Attachment 438994


I spent a stupid amount of time trying to dial in how much oil was being sent through the new oil line. Both of my spare #3 oil metering units sent 3-4 drops of oil to the ballnut with each pull of the manual oiler, which I thought was too little oil. Meanwhile my spare #4 oil metering unit sent 26 drops to the ballnut which is way too much. Since a #4 metering unit is only supposed to be twice the flow of #3 metering units, this didn't make any sense. So I finally broke down and bought a pair of oil metering units - a #3 and a #4 - off of eBay for about $14. The new #3 metering unit flows about 10 drops of oil per pull of the manual oiler and that is perfect. I guess my two spare #3 metering units are partially plugged.