Moving the ram on a milling machine.

[tonyfoale]

Good observation on lubricant displacement due to weight, not something that is always considered.

I don't know exactly what the weight of the ram and head is on a Bridgeport but guessing I would say near 200 kg. which is supported on an area of 0.032 m^2 so the pressure is g * 200/0.032 = 61.4 kPa. which is very low and hence surprising that it matters in terms of squeezing lubricant. I guess when you apply that pressure for a few years the effect builds up.