View Full Version : Jet Mill/Drill Lube Questions

Cannon Fodder
09-27-2018, 02:19 PM
Greetings and apologies beforehand, newbie machine owner.

I purchased a small home machine shop a little while ago that included a Jet-16 mill/drill with a R-8 spindle.

I have searched the internet, called Jet and still haven't gotten a clear answer of what actually goes into the zerk fitting on the lower part of the quill, I have seen some references to oil and some to grease. A friend recommended I ask here to see if I could get some clarification or someone's experience with the machine.

When I spoke with Jet technical support none of their drawings show the zerk fitting so the tech was unsure and stated that I could do either. I did receive a manual from Jet but it refers to a machine with a 3MT spindle and using a medium consistency machine oil, but the manual isn't a good scan so the images are not real legible.

Jet-16 12-speed
9-3/8x23-1/2 table
Built 8/1980-Taiwan
R-8 spindle

While waiting for Jet to respond I did look over the JMD-15/18 manual, but those machines have sealed bearings. That manual recommended Mobil Heavy Medium for the ways/column and Mobilith AW2 for the rack. I already had the Mobil for the lathe and bought XHP-222 for the rack as it appears the Mobilith AW2 has been discontinued, though I don't think the rack grease matters much.

Would actual way oil (Vactra #2 specifically) be better to use than the Heavy Medium, again the Jet-16 manual only specified a "medium consistency machine oil".

Thanks in advance for any assistance.

09-27-2018, 02:44 PM
Way oil is better for the ways than Mobil Heavy Medium as it has the tackifiers and anti-stick-slip additives.

The spindle is pretty low speed so it's not overly picky about grease or oil. I'd try with oil first and if it ends up spraying on your face then move to the mentioned XHP 222 grease.

09-28-2018, 12:39 PM
I think I'd want to see a picture of where this zerk fitting is located so we can take a better guess on where the zerk is feeding the lubricant.

Most mills will be using larger size bearings. And since the speeds of the balls in the races can get moving pretty fast at the higher speed ranges I would think that the last thing you/we would want is bearings that are packed full of grease. The viscous drag on the motor would be very high for starters. And the bearings would heat up from all that power going into smushing the grease around when it has nowhere to go to get out of the way. And that would certainly become the situation after enough grease were pushed in through the fitting.

On the other hand a good layer of grease between the quill and the head casting would do much for smoothing and cushioning the travel of the quill in the head.

Cannon Fodder
09-28-2018, 01:31 PM
Thanks, below is not my specific machine but the fitting is in the same spot:


Thanks again.

09-28-2018, 02:28 PM
That sure does look like it could be a fitting that feeds the lower bearing. If it does connect to the bearing then it would imply to me that there should be a match up in the upper area for the upper bearing.

If it is the bearing then I'd go with a small shot of a medium oil from time to time. No need to flood it when you only need a light film to do the job. I sort of assume here that the oil will leak its way out through some manner of bottom seal in time. And again if it is the bearing, which that MT3 version manual would appear to make it, then if you run it at some higher speed and inject the oil while running you should hear a difference in the sound.

And a hearty WELCOME ABOARD to the forum ! ! ! ! :)

Cannon Fodder
09-28-2018, 03:34 PM
Thanks, I think I will pull the zerk and see what is there. I have found no other zerk on the machine but haven't fully looked it over at this time, there may be one under the spindle pulley.

Thanks for the help and welcome, I look forward to re-learning what I have long since forgotten.