I just received my new Sherline mill model 5410. After setting it up I noticed that the pulley on top of the headstock does not turn round. Watching the edge of the pulley I see a slight "up-and-down" movement when the pulley rotates at low rpm.
I do own a dial indicator, but unfortunately I do not yet have the necessary clamps to get it into position to measure the amount of the movement of the pulley. But I was able to clamp the milling vise to the mill's table and hold the dial indicator against the side of the end mill holder (P/N 3079). When I slowly turn the pulley by hand then I measure a deflection starting at 0 and going up to a maximum of 0.06 mm (0.0024 inch) at the opposite side (180 degree turn), and back to 0 at 360 degrees. If I measure at the shank of an end mill put into the holder then the deflection goes up to 0.065 mm (measured on the plane surface, just above the blades). I made sure that the end mill holder is screwed completely to the head stock, and the threads are clean.
I am new to machining and I am not quite sure if this amount of "un-roundness" is within the normal tolerances of the machine, or if this is something to worry about. What is your opinion?
Juerg