Tips for a manual milling machine

In my October column, I explained how the design of manual milling machines could be improved. This month, I share some tips for enhancing the operation of a manual mill:

• Get an indicator with a vertical dial. This beats craning your neck like a bird hunting a worm all around the mill when zeroing a part.
• For tramming the head, make several long indicator holder bars to sweep a larger arc. If you have trouble indicating a bore you think should be round, check the head tram condition. Typically, you would see a longer direction or equal but mismatched numbers. If the head is out, you’re out on your head.

Using an indicator with a vertical dial beats craning your neck when zeroing a part. All images courtesy T. Lipton.

• Button-type indicators slide over the T-slots easier than a test indicator when tramming.
• Use a high-quality combination square on the mill. You will be surprised how close you can get. I checked one of my combination squares against a master square comparator and was happy to find it was within 0.002 ” of square at 10 ” off the surface plate.
• Prior to discovering special-toothed wedges, I used 5/8 ” dowel pins as backstops in the mill like everybody else. But the wedges fit tightly in a T-slot of any width. You can easily vary the height and even use them for special clamping jobs.

Special-toothed wedges are effective as backstops in a mill.