Fixing a Leaky RF-45 Mill Head - Grizzly G0519
#31
I got so anxious to post my pictures I didn't post much of an explanation about why I have been doing this job. I did explain that I had a leak but not from where or my suspicions of why. This message should have been the first in this thread but it's easier to write now after a few discoveries and while I wait for the paint to dry. I hope this is helpful to those contemplating this repair.

My leak was from the quill end of the mill. Oil was coming out from where the lower bearing is. I verified this by removing the threaded plate with three indents. This is not good because the oil washes the grease out of the tapered bearings. With this being a home use mill, I could have ignored it but being picky about tool maintenance, I wanted to fix it. I'm also up for an adventure of fixing something I've never fixed before.

The RF-45 and RF-40 Chinese and Taiwanese Mills have a gear box where six speeds are available. The head is much like a simplistic automobile transmission. The speed selectors move gears that slide on the internal shafts using brass shoes to move them. There are 3 major seals on the input and output of the gearbox and two smaller seals on the speed selector shafts. There are four shafts that run vertically inside the head/gearbox. There is one shaft for the motor input with one seal, one shaft for the spindle output with two seals, and two intermediate shafts where the speed selection occurs which are internal only and have no seals. The motor input shaft is at the top of the head and is not likely to leak much. Oil would not have anywhere to go from this seal. It mostly protects the motor. The output shaft which drives the spindle through a sliding spline has two oil seals and is buried inside the head. These seals are redundant. I think that there are two in case a little oil gets past one seal. When these seals leak, the oil gets into the quill /spindle assembly. There are two directions for the oil to take when it gets past these seals, past the quill, or through the quill bearings. Most of my leaking oil was coming through the quill bearings.

As I disassembled my mill I discovered two interesting things which may explain why I had a leak. First, the seals around the shaft that drives the spindle were installed upside down with the lips pointing away from the oil filled head. Second the round plate the seals were installed inside of is attached to the cast iron head with three screws and a gasket. My gasket showed signs of oil getting past it which circumvents the seals. I fairly certain that upside down seals and a leaking gasket are the root cause of my leak.

Unfortunately getting to these two seals requires taking the whole head apart. Once the head is apart and the seals are being replaced, it made sense to me to also replace the bearings. That said, I have to admit that none of my bearings looked bad. I could have taken the mill apart and just replaced the seals and probably been good to go. Doing so would have simplified the job because I would not have had to pull any bearings. If your mill is clean inside, you may consider just replacing the two quill drive shaft seals. My mill had a brown muck inside which confirmed that I needed to replace the bearings.

I thought about this repair for over a year before starting. I knew it would be a big job. Thanks to Ed for giving me the kick-start I needed by starting his mill repair first. Be sure to follow his thread which has photos of parts of the repair I failed to photograph.
henryarnold, proud to be a member of MetalworkingFun Forum since Apr 2012.
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#32
This is my first work with a shop press. If you think that I'm using the wrong technique, please post your suggestions so that others don't follow my mistake. It is important to consider how you press against bearing because they can be damaged if you do it wrong. Hopefully what I'm showing is correct.

After pressing the lower bearing race in place shown in previous section.
   
I greased my bearing on the spindle by hand with latex gloves. I thought this would be easier that trying to press a greased bearing into place. I also reinstalled the pin that guides R8 holders. On my mill there is a second one nearer the end that does not poke out. Maybe a spare?
   
I returned the spindle to the quill and dropped the new upper bearing race onto the spindle. I used the old bearing race as a backer for pressing the new one in place.
   
I placed the quill assembly upside down in the shop press resting on the old bearing as a backer and then pressed it into place. Gently, the bearing should not be very tight because preload should be adjusted on this bearing.
   
Upper bearing in place.
   
Install keeper plate and castellated nut. Tighten and back off about 1/8 turn. Set the keeper tab into the nut slot.
   
Completed quill assembly. Re-install the bottom threaded cover.
   

The quill assembly is now complete. Next time I'll begin reassembly of the head. There will be a couple day delay as my paint drys.Smile
henryarnold, proud to be a member of MetalworkingFun Forum since Apr 2012.
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#33
Henry,

Very nice documentary. Much better than mine. Smile

Maybe you should say something about how much you packed the bearings with grease for those that don't know you should not fully pack a tapered roller bearing with grease in certain situations.

Ed
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#34
(05-04-2012, 11:55 PM)henryarnold Wrote: Here's the interior of my head. The brown stuff looks like rust but it is not rust. I'm not sure what it is but it looks and feels like a polishing compound which makes no sense. This contamination is reason enough to replace all bearings. There was a brown sludge in the bottom of my gearbox.

You are not the only one to find "brown muck" in the bottom of the gearbox in an RF45 type of mill ...

A similar issues with a brand new IH mill ... a "heavy duty" RF45.

Arvid
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#35
Wow! That's scary. The brown muck had iron filings in it.

Ed
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#36
Henry,
Thanks for a very well documented & photographed thread
John
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#37
(05-07-2012, 12:00 PM)EdAK Wrote: Henry,

Very nice documentary. Much better than mine. Smile

Maybe you should say something about how much you packed the bearings with grease for those that don't know you should not fully pack a tapered roller bearing with grease in certain situations.

Ed

Ed, I actually wasn't aware of this so I may have over-packed mine. I put on a pair of latex gloves and worked the grease into the bearings. I've done a similar packing of auto wheel bearings. How can I tell if I over packed them?

Henry Arnold
henryarnold, proud to be a member of MetalworkingFun Forum since Apr 2012.
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#38
(05-08-2012, 12:59 PM)arvidj Wrote:
(05-04-2012, 11:55 PM)henryarnold Wrote: Here's the interior of my head. The brown stuff looks like rust but it is not rust. I'm not sure what it is but it looks and feels like a polishing compound which makes no sense. This contamination is reason enough to replace all bearings. There was a brown sludge in the bottom of my gearbox.

You are not the only one to find "brown muck" in the bottom of the gearbox in an RF45 type of mill ...

A similar issues with a brand new IH mill ... a "heavy duty" RF45.

Arvid

THANKS!,
This describes my mill's interior exactly so I assume I had the same type of brown sludge. I used the Dawn soapy water treatment followed by high pressure air to blow out the water.
henryarnold, proud to be a member of MetalworkingFun Forum since Apr 2012.
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#39
Henry,

I've read that for machine tools you should pack the grease from 1/3 - 1/2 full in the bearing. Full packing is suppose to be bad for tapered roller bearings on machine tools. I don't know the physics behind it, just what I've read. I think it may justify some additional research.

Ed
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#40
Does anyone else have any comments on my use of industrial oil base paint on the interior. If I made a mistake, it's not too late to fix it. You guys got me worried so I'm going to test it after it dries by filling one of the cavities with oil for a couple of days and make sure the finish doesn't soften.

Thanks for the warning.
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