Excello (XLO) 602 Oil Leak

[bkahler]

I performed a rebuild of my mill several years ago and at first all seemed good. During the rebuild I replaced the oil seal at the bottom of the back gear gearbox. A few months after assembly and mill use I noticed oil on the bottom of the quill housing near the spindle. At the time I made the assumption that I had screwed up the installation of the oil seal and figured I needed to replace it, so I proceeded to do so.



Fast forward a few months and the oil leak returned.

When I replaced the seal the 2nd time, I verified the shaft had no scoring and it felt smooth. I also added sealant around the outside of the seal before pressing it into the opening.

Taking a closer look at this new situation I noticed that the sides of the back gear housing seemed to be damp in a few places. Also, oil had started puddling at the bottom of the quill scale/stop where the threaded shaft is located. Since the quill scale is above the bottom of the spindle that meant the oil had to be coming from somewhere above the spindle seal

In the picture below I've drawn two green lines. The lower one is the bottom of the back gear casting and the upper one is where the back gear casting mates with the variable drive housing.



What I had never notice before is that there is a gasket between the back gear casting and the variable drive housing. Looking closer at my mill I found that there are several damp spots on the side of the casting where oil has been slowly weeping down the outside of the casting until it reaches the bottom of the spindle. All this time I thought it was the spindle seal when it reality it is probably the gasket.

Have any of you ever dealt with replacing that gasket? I've had insides of the variable drive box apart but never realized there was a gasket in there.

Thanks.

 

[Rauce]

I performed a rebuild of my mill several years ago and at first all seemed good. During the rebuild I replaced the oil seal at the bottom of the back gear gearbox. A few months after assembly and mill use I noticed oil on the bottom of the quill housing near the spindle. At the time I made the assumption that I had screwed up the installation of the oil seal and figured I needed to replace it, so I proceeded to do so.

View attachment 37322

Fast forward a few months and the oil leak returned.

When I replaced the seal the 2nd time, I verified the shaft had no scoring and it felt smooth. I also added sealant around the outside of the seal before pressing it into the opening.

Taking a closer look at this new situation I noticed that the sides of the back gear housing seemed to be damp in a few places. Also, oil had started puddling at the bottom of the quill scale/stop where the threaded shaft is located. Since the quill scale is above the bottom of the spindle that meant the oil had to be coming from somewhere above the spindle seal

In the picture below I've drawn two green lines. The lower one is the bottom of the back gear casting and the upper one is where the back gear casting mates with the variable drive housing.

View attachment 37324

What I had never notice before is that there is a gasket between the back gear casting and the variable drive housing. Looking closer at my mill I found that there are several damp spots on the side of the casting where oil has been slowly weeping down the outside of the casting until it reaches the bottom of the spindle. All this time I thought it was the spindle seal when it reality it is probably the gasket.

Have any of you ever dealt with replacing that gasket? I've had insides of the variable drive box apart but never realized there was a gasket in there.

Thanks.

On my mill there was no gasket, both surfaces you noted on the drawing had a silicone sealant.

I did not clean it off and put fresh sealant on when I had it apart and it did leak a little bit but not enough to prompt me to go back in there to fix it.

 

[bkahler]

On my mill there was no gasket, both surfaces you noted on the drawing had a silicone sealant.

I did not clean it off and put fresh sealant on when I had it apart and it did leak a little bit but not enough to prompt me to go back in there to fix it.

It wouldn't surprise me if the silicone on yours was from a previous repair. On mine I wouldn't be surprised if it doesn't have a gasket. As old as it is and as bad as the condition was, I'm sure someone had been into it before. Mine leaks enough that I have oil everywhere under the head. Oddly enough, nothing mounted in a collet ever gets oil on it. That particular area stays dry.

It's going to have to be fixed one of these days

 

[Susquatch]

I did not clean it off and put fresh sealant on when I had it apart and it did leak a little bit but not enough to prompt me to go back in there to fix it.

It's going to have to be fixed one of these days

Looking closer at my mill I found that there are several damp spots on the side of the casting where oil has been slowly weeping down the outside of the casting until it reaches the bottom of the spindle.

Please allow me to express a contrarian point of view. The Bridgeport operators manuals specify a few drops of oil down the spindle draw bar - ostensibly to oil the drawbar threads, the tapers, and the drawbar thrust washer assembly. That oil inevitably drips down the spindle once in a while.

The spindle cap on my Hartford even includes an oil drain.

Personally, I see no problem with a little oil seepage anyplace on the spindle. Ideally, what goes in must come out taking the crap with it.

Also, if the head were designed to seal, they would not include oilers, the entire head would be a giant oil bath. It isn't.

So I wouldn't worry about the oil seeping out the head seams either and in fact would expect about as much to come out each day as I put in there each day via the oilers - just taking a few days in transit.

Lastly, I don't recall any gaskets in any of the heads I had apart. Nor would I expect any.

 

[Rauce]

Please allow me to express a contrarian point of view. The Bridgeport operators manuals specify a few drops of oil down the spindle draw bar - ostensibly to oil the drawbar threads, the tapers, and the drawbar thrust washer assembly. That oil inevitably drips down the spindle once in a while.

The spindle cap on my Hartford even includes an oil drain.

Personally, I see no problem with a little oil seepage anyplace on the spindle. Ideally, what goes in must come out taking the crap with it.

Also, if the head were designed to seal, they would not include oilers, the entire head would be a giant oil bath. It isn't.

So I wouldn't worry about the oil and in fact would expect about as much to come out each day as I put in there each day - just taking a few days in transit.

Lastly, I don't recall any gaskets in any of the heads I had apart. Nor would I expect any.

The excello is a completely different design. Nothing like a Bridgeport apart from some similarities in layout.

The excello back gear assembly, above the spindle is in an oil bath. I can’t recall how much it holds but probably a quart or so. There’s an oil seal that keeps it from going down the spindle and then sealing faces on the top, and more importantly, the bottom face of the housing where it mounts to the lower head assembly. Whatever oil was used originally is no longer available and the officially recommended replacement is automotive ATF.

Theres a spot on an excello for oiling the quill and fill ports/sight glass for the back gear. That’s pretty much it. Sealed spindle bearings with grease.

 

[Susquatch]

The excello is a completely different design. Nothing like a Bridgeport apart from some similarities in layout.

I see! Said the half blind old guy!

Sounds nice. I never did like the BP design. Of course, I gotta keep in mind that for my needs, the BP/Hartford design is just fine even if less than ideal.

 

[Rauce]

I see! Said the half blind old guy!

Sounds nice. I never did like the BP design. Of course, I gotta keep in mind that for my needs, the BP/Hartford design is just fine even if less than ideal.

There’s pros and cons to each style.

The guts of the head are more easily accessed on a BP style head. On an Excello you can’t get the mechanisms that handle power quill feed without removing the head from the ram. I also like the way a BP type head auto disengages the power quill feed.

The way the head on an excello mounts to the ram and handles nod and tilt is more rigid. The quill has an extra inch of travel. The back gear also does not change the direction of spindle rotation.

 

[Susquatch]

I also like the way a BP type head auto disengages the power quill feed.

I'm not thrilled with it. As I understand it, the single biggest problem with defective power quills is a sticky release. If they ever stick - even just once - they crash and the result is a stripped worm gear. The power feed is broken on 4 out of 5 BPs I look at. The good news is that it doesn't affect manual operation of the quill but power feed is gone.

 

[Rauce]

I'm not thrilled with it. As I understand it, the single biggest problem with defective power quills is a sticky release. If they ever stick - even just once - they crash and the result is a stripped worm gear. The power feed is broken on 4 out of 5 BPs I look at. The good news is that it doesn't affect manual operation of the quill but power feed is gone.

Interesting, I haven’t seen a broken one before but I haven’t done that much shopping.

On the excello there’s no automatic disengage, just a friction clutch.