Moving the ram on a milling machine.

**tonyfoale** · Jan 4, 2018, 02:54 AM

I was just discussing moving the ram on a Bridgeport with a friend. A while back he had problems moving his and about a week ago I needed to move mine, which is an unusual occurrence. I thought that my solution might be of interest here.

The ram just didn't want to move and I was fearful of shearing a drive pin (just guessing that there was something like that in there) between the external lever and internal pinion. I placed a bottle jack between the table and the head and took the load off the slide. That let me squirt some very thin oil in there, It had been lubricated with grease. I then switched to the rear end, where I added a long lump of wood to the jack to reach from floor to slide, and repeated the oil squirting. It still didn't want to move after removing the jack so I jacked up the front again and managed a small movement with the jack in place and the load off. Then I removed the jack and the ram moved OK, albeit a bit stiff. I cycled it fully several times washing the old lubricant off and putting new on. Smooth as silk now, but for how long? If the ram is not moved for a long period the weight gradually squeezes the lubricant out.

**olderdan** · Jan 4, 2018, 06:30 AM

Good observation on lubricant displacement due to weight, not something that is always considered.
I am in the habit of rotating my lathe chuck a few times by hand before powering up (plain bearings).

**tonyfoale** · Jan 4, 2018, 08:03 AM

Originally Posted by olderdan

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.