Seal Lathe Apron Leak

All my time re-engineering stuff and rebuilding machines I have made my own gaskets. Every time someone comes into my shop promoting the best 'in tube' option, I let them - they're the expert in RTV, aren't they? So far 6/6 failures. My cardboard with grease rubbed into it gaskets: 100% success (no leaks)... Over the past 6-7 years I've been buying the foam sheet type gasket material for special projects, and they even work better than cardboard. I have 2 different thickness/stiffnesses and that covers everything that I've wanted to do. just my 2 cents.

Before anyone gets too insulted. I think RTV in the right hands, applied properly can be a great gasket. I just haven't seen it happen, and I certainly don't have the right info/technique to do it myself. So I do what works for me.
 
So it's a machined metal, non gasketed joint, that is designed to hold oil? I'm going with that, if I'm wrong, stop reading because I'm out in left field...



Cleaned them how? Specifically, were there any abrasives involved?


How tight is more than enough. This can be a problem, as a machined joint that seals dry will have a fairly low clamping force. Well, prior to cost effective mass production with 3D CNC machining at 50 millionths of an inch anyhow.



You're positive it was not a pre-existing sealant that might be called out in a manual somewhere?


I never was a fan of that stuff. I've used plenty of it,

Loctite 515 or a direct cross reference would be my first choice. Flange Sealant or Gasket Eliminator are two common names if you cross it. It does "harden", but not what you're worried about. It stays flexible in lighter castings, and it'll come apart pretty reasonably in future services. It's not reusable, but It's an anaerobic sealer, so it won't dry in the tube, one tube will last a lifetime. You're just fighting gravity, right? No pressure on that oil? If that's the case, no setup time is required, you can bolt it together and fill it up. You still want reasonable to light torque on the fasteners responsible for the joint. Cranking down on them will start to pull apart the sectons between them, and open a gap.
Yes, the apron is a typical cast iron lathe apron that is two-part front and back halves and holds gear oil.

The inside of the apron was quite clean....a few chips at the bottom that had snuck in through the opening for the half-nut, but just a couple. I drained the oil and was able to simply wipe out the old oil and a bit of residue from the bottom with shop rags and a few shots of carb cleaner. I used a very fine bronze wire wheel on a bench grinder to clean the mating surfaces. This is a wheel that won't remove skin from my finger when I hit it (regularly)....no chance it damaged the casting. The apron sat sat open for a week waiting for a part so it was clean and dry when I reassembled.

I didn't use a torque wrench when I tightened the bolts, so I can't give you a figure. When I said "more than enough" I meant they weren't loose, not that I cranked down on them a lot...I'm sure that wasn't clear. I used a 6" allen wrench and went in a pattern all the way around until they all felt snug and then gave each a little pressure and didn't feel any movement. I went around at least three times. The next day I saw it had leaked a bunch and put the allen wrench on each one another time and there was no change.

The manual doesn't mention anything about assembling parts like the apron so no luck there. I'm not positive it wasn't sealer remnants, but it looked like old dried oil varnish and it was only in some spots, so not like it was applied all the way around upon assembly.

Yes, just fighting gravity, so no pressure involved. Loctite 515 looks like a good choice...thanks!
 
Run a single line of dental floss. Hold it in place with a dab of grease or hylomar so that you can bolt it together.

Airplane engines were put together with a silk string. While the floss isn't FAA approved, the wife gets mad when I start pulling on her scarves.
 
All my time re-engineering stuff and rebuilding machines I have made my own gaskets. Every time someone comes into my shop promoting the best 'in tube' option, I let them - they're the expert in RTV, aren't they? So far 6/6 failures. My cardboard with grease rubbed into it gaskets: 100% success (no leaks)... Over the past 6-7 years I've been buying the foam sheet type gasket material for special projects, and they even work better than cardboard. I have 2 different thickness/stiffnesses and that covers everything that I've wanted to do. just my 2 cents.

Before anyone gets too insulted. I think RTV in the right hands, applied properly can be a great gasket. I just haven't seen it happen, and I certainly don't have the right info/technique to do it myself. So I do what works for me.
I wouldn't try adding an actual gasket working in this case. There are a number of shafts, pinions, bearings, gears, etc that would no longer be spaced properly. Maybe it wouldn't be enough to cause a problem, but I'm not going to test that.
 
Ordered some Loctite 515....because Amazon Prime, free shipping :)

I suspect lots of stuff might work, so might as well try something I can get delivered. That just means tomorrow I'll notice it hasn't leaked more!
 
I found dozens of good uses for anaerobic flange sealant in the Army. It was a strong solution for stubborn oil leaks, and good insurance for hard to get at components. Also a good thread locker in a pinch. Not so easy to clean up the second time around, so keep that in mind. It's fantastic for true tight fitting flanges, though. Imagine that.
 
Fine polyester thread tacked down with heavy grease could work. Much along the lines of dental floss or silk. One of our high vacuum systems had an ionization gauge whose sealing gasket was made with a "deformable metal" seal which turned out to be fine solder wire. I hadn't seen that before....and never since. But it worked just fine. It was solid wire, no flux core.
 
This is just a thought, but is there an oil sight "glass" in there?

You didn't mention it, but it made me remember I had a problem with my old lathe's apron loosing about a teaspoon of heavy gear oil per night. It turned out the sight glass was fractured. I replaced it with a piece of plastic cut out from a transparent CD case.... It lasted few months in that oil bath and it cracked too. A couple of months ago I replaced it with two layers of transparent thick PET film (the material carbonated drink bottles are made of). It has been fine so far.
 
This is just a thought, but is there an oil sight "glass" in there?

You didn't mention it, but it made me remember I had a problem with my old lathe's apron loosing about a teaspoon of heavy gear oil per night. It turned out the sight glass was fractured. I replaced it with a piece of plastic cut out from a transparent CD case.... It lasted few months in that oil bath and it cracked too. A couple of months ago I replaced it with two layers of transparent thick PET film (the material carbonated drink bottles are made of). It has been fine so far.
It does have a sight glass, but that isn't where it's losing oil. It's coming from the seam along the bottom. Also, it wasn't leaking before I had to split the halves to change the pinion. If I wipe it clean today tomorrow morning there will be a couple of drips hanging from the seam and a puddle directly under them. The sight glass area is dry all around.
 
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