Mill: Head Alignment

My first post about my mill regarded aligning the head to the column. Back then I remove the column from the base so the table wouldn't interfere.

Recently I had to realign the head again, and used a much easier technique to do it. First I remove the support spring from the head so I could extend it above the top of the column. Then I chucked a straight and polish rod using my ER25 chuck. You can use pretty much anything to hold it, but it helps if it's low profile. With the rod extended a little over 4" from the chuck face, and the head could move a total of about 6" from the rod touching the table to the head reaching the top of the column.

I clamped my vise vertically to the table and used it to hold a DTI which indicated the rod. I then used Rolle's Dad's Method (RDM) to check the alignment of the rod. In my case the head was 0.0015" over 4" out of alignment.

In the middle of checking the head alignment.

I then moved the head up past the top of the column until the top two bolts holding the head together were exposed, and loosened them both. I then tightly tapped my motor mount with a rubber mallet to adjust the head. Weirdly, I found tapping it on the right side would rotate the head clockwise. After each adjustment with the hammer I'd check the alignment using RDM. From experience I knew tightening the bolts would rotate the head counter-clockwise about 0.0015" as measured with this setup, so I accounted for that.

Once the alignment was where I wanted it, I again raised the head above the column and in small increments I tightened the two bolts down. You want to get them nice and tight. I think checked the alignment again using RDM. Finally, I carefully lifted up the head until the lower head were just exposed and checked to make sure they were still tight as well, and then checked my alignment once more.

Ultimately, this way was much faster and easier than dismounting the column.