PDA

View Full Version : Millrite MVN quill bearings lubrication



softtail
12-14-2016, 02:08 PM
Another Millrite conundrum. The Timken bearings in the lower spindle are supposed to be serviced with grease every 200 hrs. The quill has a plug on the back side in which to shoot grease and it also provides access to a nut for setting bearing preload.

From what I have researched the plug on the back has been anything from just a regular plug, to some kind of plug with a small grease/oil dimple in the bottom of it (that's what mine had). Even the folks at DC Morrison are sketchy on this... probably some mid production change that didn't make it into the manuals.

Either way, the hole is way the hell up from the bearings... especially the lower bearing. There is also quite a lot of void in the spindle to fill with grease before any 'packing' of grease would happen. Basically not a snowballs chance in hell of grease getting from the access port to where it needs to be. Oil yes, grease no.. and the manual is explicit about using grease, yet it seems like a oil system.

In my bike days a company made a freewheel greaser that was basically a threaded disc with a zerk.. the freewheel was removed from bike hub, the greaser screwed into back of freewheel, and you could zerk away. A similar unit for the lower end of the spindle wouldn't be too hard.. the lower bearing is just right there.

But I am also loathe to have grease just accumulating in the spindle for years.. oil at least can wash through.

Any insight or workarounds?

chipmaker4130
12-14-2016, 02:59 PM
I know it sounds/looks crazy, but it must actually work since Milrites last a long time. I notice a ring of grease-ooze around the spindle nose on mine, indicating that the grease does indeed get to, and through the bearing. I guess the grease gob simply falls onto the bearing and gets swirled in.

softtail
12-15-2016, 03:21 PM
Just spoke with Chuck at DC Morrison. He says straight SAE 30 wt squirted down the hole once in a while has kept all their Millrites happy for 30+ years. When I brought up the manual specifying grease he said something to the effect of 'there's so much better lubrication products on the market now'. He concurred that there was little chance of grease getting to the bearings via the quill plug.He was pretty casual about it. So there it is fwiw.
From what I can gather, when bearings are greased correctly, oil actually actually seeps from the grease, lubricating the bearings. The Millrite manual also mentions accidental liquification of the grease due to high temps from too much preload.

That's as far down the rabbit hole as I'm going for a well used 1967 machine. Keep it clean and regularly shoot something down the hole are the take aways.

Here is some bearing break in info from SKF:


Standard running-in procedure
The most common running-in procedure can be summarized as follows:

Select a low start-up speed and a relatively small speed increment.
Decide on an absolute temperature limit, usually 60 to 65 C
(140 to 150 F). SKF recommends setting the machine with limit switches that stop the spindle if the temperature rise exceeds the set limit.
Start operation at the selected start-up speed.
Monitor the temperature rise by taking measurements at the bearing outer ring position, and wait for the temperature to stabilize. If the temperature reaches the limit, stop the spindle and allow the bearing to cool. Repeat the process at the same speed and run the spindle until the temperature stabilizes below the limit.
Once the bearing temperature has stabilized, continue to run the spindle for an additional 10 to 15 minutes. Then, increase the speed by one increment and repeat step 4.
Continue increasing the speed incrementally, allowing the temperature to stabilize at each stage, until the spindle reaches one speed interval above the operating speed of the system. This results in a lower temperature rise during normal operation. The bearing is now properly run-in.

This standard running-in procedure is time-consuming. For a medium- to high-speed spindle, each stage can take anywhere from 30 minutes to 2 hours before the temperature stabilizes. The total time for the running-in procedure can be 8 to 10 hours (diagram 1).
Short running-in procedure
An alternative to the standard running-in procedure reduces the number of stages and shortens the overall running-in time. The main steps can be summarized as follows:

Select a starting speed approximately 20 to 25% of the attainable speed for grease lubrication (→ Product tables) and choose a relatively large speed increment
Decide on an absolute temperature limit, usually 60 to 65 C (140 to 150 F). It is advisable to set the machine with limit switches that stop the spindle if the temperature rise exceeds the limits set.
Start operation at the chosen start-up speed.
Monitor the temperature by taking measurements at the bearing outer ring position until the temperature reaches the limit. Care should be taken as the temperature increase may be very rapid.
Stop operation and let the outer ring of the bearing cool down by 5 to 10 C (10 to 20 F).
Start operation at the same speed a second time and monitor the temperature until the limit is reached again.
Repeat steps 5 and 6 until the temperature stabilizes for 10 to 15 minutes below the limit. The bearing is run-in at that particular speed.
Increase the speed by one increment and repeat steps 4 to 7.
Proceed until the bearing is running at one speed increment above the operating speed of the system. This results in a lower temperature rise during normal operation. The bearing is now properly run-in.

Although each stage may have to be repeated several times, each cycle is just a few minutes long. The total time for this running-in procedure is substantially less than for the standard procedure.

chipmaker4130
12-15-2016, 06:43 PM
Thanks for posting that info. Maybe I'll switch to oil.

softtail
01-05-2017, 02:07 PM
Went with Timken high speed spindle grease.

More info on grease here: http://bbs.homeshopmachinist.net/threads/72289-Mobil-Beacon-325-grease/page2?highlight=mobil+beacon