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04-30-2013, 01:39 AM #1
Mill One-Shot Oiler Questions - Leaks
The oil in my one-shot lube tank ends up in the base over night. The oil pump/tank is built into the mill saddle. The plunger head mounts on the saddle left side and seals with a gasket. I'll be replacing that gasket, but I also noticed that all the compression fittings on the manifold seem to leak as well. I pulled some apart, and they don't look (to me) like they will ever really seal.
The fittings consist of threaded bushing that pushes the copper tube into a coned washer that flares the tube end. There is no compression ring (I guess it's supposed to be part of the bushing). Even if the flare seals. it looks like a good seal would also require the back of the cone to seat perfectly inside the manifold, but I can see that that surface is very rough inside the manifold. Oil seems to leak past the bushing threads (there is no tape) and also between the copper tube and the hole in the bushing. Tightening the bushings didn't help.
There are currently no meter valves in this set-up. The copper tubes just go off to their destinations. I suppose there is little back pressure, but I prefer to not have the tubes empty out. Also, since the manifold is below the lube tank, I seems like there might be nothing to stop the tank from dripping out through the various manifold leaks.
1) Should I just toss the manifold (it's threaded 10mm/1mm pitch), and get new tubing and fittings with normal (to me anyway) compression rings? i.e. as shown here:Bestline Products - Lubrication Fittings
2) Should I stay with copper tubing or switch to plastic?
3) Lots of threads on the this topic say that metering valves are required. This mill doesn't have them now, and I would have no idea what flow rates to get for each.
4) I noticed this "regulating" manifold on Bestline: http://www.bestlinepro.com/images/pr.../B-6-image.jpg. Would this give me the same flow adjustment that meter valves provide? This seems better because it would let me "tune to fit", but in lots of forum searching on this topic, I've never seen this manifold mentioned.
Looking for any guidance that can be provided.
04-30-2013, 02:11 AM #2
My knee mill oneshot luber is the same. The metering is done in the orifice size of the pump itself.
On mine the flare nut pushes the olive section into a seat inside the pump proper, maybe theyve become work hardened over time and annealing the olive might fix the leaks. However the whole lube tank shouldnt end up in the sump regardless, as the pump itself is a positive displacement pump with two ball seats for valves putting out a metered shot each actuation. If it is, two or more of your ball's are stuck off their seats.
If you go for alternative tube materials, you may not have the clearance or flexibility to run them as the copper tubes fit tiny holes in the castings and snake through gaps, and stay put by dint of being semi rigid. I'm certain I don't ever want to have to replace all of the ones on my mill given their routing and awkwardness.
04-30-2013, 02:15 AM #3
Also, if it is generating enough pressure to pump past the threads, your tubes are probably sludged up and blocked, like you say they're just open ended so should offer no backpressure to do this. Its pretty common to come to a older machine and find the oilers all blocked with sludge.
The two which were like this on mine I alternately shot through with acetone then shop air till I blew the blockage out. It took a couple of cycles...
04-30-2013, 02:43 AM #4
Done well, they not only seal as good as can be, they are physically strong w/r vibration or pull-out. More labour-intensive, but also slightly less costly and somewhat more compact, overall size-wise than compression fittings.
Metering is a separate issue. I'd want to look at Bijur at least as a sanity-check & cost comparison even if determined to select some other make. Bijur have been the go-to for most machine-tool makers for a Very long Time Now, so they must have been getting it right more often than not.
04-30-2013, 02:58 AM #5
On the flared fittings, are the nuts usually inserted without tape? I ask because, even if the flare seals to coned washer, from the look of it there is nothing to stop oil from getting around the outside of the cone and back out through the threads after it passes through the center of the cone. To get a seal at the back of the cone seems like it would require two perfect surfaces, and the manifold is far from it at the back of the threads.
04-30-2013, 04:21 AM #6
Its made of copper, therefore if its soft enough provided it isnt age hardened to deform when tightened up to form a perfectly matching surface to whats there.
No tape is involved at all.
04-30-2013, 12:18 PM #7
Mill One-Shot Oiler Questions - Leaks
Would 30 year old copper cones be age-hardened? They don't look deformed at all, but the inside of the manifold looks like it has some scratches. They may be from when I probably over-tightened things while trying to stop the leaks. If the cones are hardened, can they be annealed?
04-30-2013, 12:41 PM #8
Annealing of copper 'on site' and near-as-dammit 'in situ' is a traditional plumber's age-old standby for getting rigid tubing to where he needs it to be, and flaring tubing really does NOT want old, stiff, hard material. It can split in a New York Minute, ELSE vibration-crack just outside the clamping hardware.
You really can find out tons of info about the fittings, the tools, and the methods - even step-by-step and videos, probably - by searching plumbing websites, even Googling flaring tools and rounding tools. All part of THAT craft's stock in trade.
To machinists, it is all merely an infrequent side-show. There will be expertise in the room, but it isn't as common a need HERE as it is among plumbers and fitters of high-pressure hydraulics, steam, compressed gases (my entry to it) and such.
04-30-2013, 12:54 PM #9
If you choose to anneal the copper tube (or any copper) all that needs doing is to heat it. Dull red is easy to see. It does not need quenching at all but quenching will not hurt it either. The only benefit of quenching is it lets you handle the part sooner without getting burned. The heating does the anneal not a rapid quench.
04-30-2013, 04:15 PM #10
Anneal as per Rob F's instructions above, and don't overtighten it next time, less is more and you should only consider nipping it more after you have a slight weep. I have used this technique on fittings, pipework, head gaskets etc. Always the same, dull red, let it aircool and try not to drop it (especially if you were living at home using the gas ring to heat a triumph twin head gasket, and your mum had just had a brand new blown vinyl kitchen floor installed, that figure of 8 was there for years...)
04-30-2013, 04:24 PM #11
Just 'coz the buggers only ignited cleanly when touched-off by the gas ring .. and didn't always align with the open kitchen window...