[torinwalker]

I'm restoring an Ex-Cell-O 605 CNC milling center to operating condition and after removing the cover to the Z-axis ballscrew, I noticed a thin black plastic oil tube that had broken into several little pieces laying on the bottom bracket around the axis bearing.

The copper oil plumbing comes into the head to a fixed compression fitting that sits on the left side of the ballscrew about midway along the Z axis. A plastic tube then connects via a compression fitting to this main oil feed and runs down for a few inches then curves back up and attaches to another fitting on the ball-screw nut.

I have no idea why the tube broke, and am quite puzzled by why it broke into so many pieces. Some of the pieces appear to have been severely crushed by the Z-axis mechanism. My guess is that it was too cold in my shop while I tested the Z-axis causing it to break. Alternatively, it was a prexisting condition (which may spell trouble for me in the future. The ball screw was nice, shiny, and lubricated, so I'm hoping for the best, but the bottom bearing however is missing 1/4 of the seal. Yikes.)

At any rate, I have these little bits of unidentifiable black tubing (see photos) with the approximate dimensions: 0.095" OD x 0.05" ID. It's difficult for me to measure the tube dimensions exactly, but it doesn't appear to be a 1/16 ID tubing. I'm hoping I'm wrong.

The tubing is also quite rigid given that it's supposed to flex with the z-axis. I'm surprised, really, considering that it makes a full 180 degree turn inside the head with a radius of roughly 1.25". I would have expected a more flexible material.

Is anyone familiar with this type of tubing? Anyone know what kind of material this might be? If I can identify the material, I can probably find a supplier. If however you know that too, I'd appreciate it.

When I replace the tubing, I'm going to cut a slightly longer piece and coil it around one full time before connecting it back to the fitting. Hopefully that will prevent it from cracking in the future.

I'd also be interested in your opinion regarding suitable tube material types. Fluropolymer tubing seems like a good choice.


Torin...

[torinwalker]

Bless the Internet. I found a part number on one of the junction fittings and low and behold, I came up with a rather well known manufacturer of lubrication systems called Bijur. It turns out that this little tube is a 3/32 OD Black Nylon tube, and all I have to do now to get 12 inches of this tube is buy a 100-ft coil of the stuff and a mere fifty compression sleeves (of which I'll use only two.)

With any luck, Bijur will sell or sample a smaller quantity, or point me to a distributor who can deal with smaller quantities.

Does anyone have 12" of 3/32 Black Nylon (.02" wall) and two matching compression sleeves they can sell me for a couple of bucks?


Torin...

[TarHeelTom]

Don't know if you've priced any of Bijur's stuff, but evidently it is manufactured from solid gold, then platinum plated.

Here's a couple of sources.

Bridgeport Mill Parts- Servo Power Feeds-Icai-Online.com
Don't remember this guys name at the moment (just looked it up, Wayne Plume). He's a bit of a strange duck. Although he'll sell you exactly what you ask for, he'd rather talk to you and find out what HE thinks you really need. And he's more likely to be correct than you are. And he sells small quantities.

Gromax Online
Gromax sells a Taiwan "clone" of a Bijur lubricator. Only thing I'd do different here is to buy the one with the automatic low level switch to warn you that you're almost out of lube oil.

One nice thing is that the Gromax has an output pressure gage built in. I remoted this to the head. When the pump operates, the oil pressure comes up and stays for a few seconds, then drops back to zero. When your lube metering units clog up, it'll take longer to drop back to zero, thus warning you that you're not getting lube somewhere.

Tom

[TarHeelTom]

The copper oil plumbing comes into the head to a fixed compression fitting that sits on the left side of the ballscrew about midway along the Z axis. A plastic tube then connects via a compression fitting to this main oil feed and runs down for a few inches then curves back up and attaches to another fitting on the ball-screw nut.

Torin...

Go here: Tom Wade Machinist Technical Reference and look at the "Lube System Design" booklet, which came from the Bijur website.

Probably the copper line runs to a "lube metering unit", then the plastic line runs from there to the delivery point.

Tom

[torinwalker]

So it turns out that Bijur has locations all over the place and it just so happens that a distributor is within driving distance.

Tom, you're exactly right. The copper line comes out from the head, goes into a two-port junction that is bolted in place, then an FUD 00 (double-odd) flow meter goes into the other. The tube turns out to be a 3/32 OD x .020" black nylon tube - length still undetermined.

Tube is $1.20 per foot, 10' minimum, and the compression sleeves are a mere $0.40 each.

I'm in heaven!

The only question I have now is, will the icy temperatures of my unheated shop cause the replacement nylon to become brittle and crack? As far as I can tell, Nylon becomes brittle at very low temperatures (well below my garage), so it couldn't have cracked as a result of me running the z-axis while the machine was cold.

Hey, thanks for the advice. It all turned out for the best.

If anyone needs a small section of 3/32 x 0.02" wall clear (they didn't have black) nylon tubing, let me know. I have lots of it!


Torin...

[Al_The_Man]

I would also replace the metering device on the end of the lube line, in fact after so many years use, all the metering devices should be replaced as a standard maintenance procedure.
Al.

[torinwalker]

That's not a bad idea - it is a rather old machine, and if I've found these problems, the oil system is probably suspect in other places too.

However, I'll probably just check them first to see if they're clogged. No sense in fixing what isn't broken. They're probably very mechanically simple - a precise hole to restrict fluid for a given pressure. Assuming I have the right drill or wire diameter, or perhaps even a solvent like carb-cleaner, I can probably clean them rather than replace them.

I guess I'll find out whether it's easier to clean or replace when I get to it. Right now, my bigger concern is replacing the lower bearing on the z-axis ballscrew that is missing a quarter of the shield. It's a failure just waiting to happen, especially with all the metal debris that made its way up in there from years of milling.


Torin...

[Al_The_Man]

You may be wasting your time trying to clean them, they have a very fine filter in them that the oil gels in overtime.
I ended up replacing them all on machines I have rebuilt.
Al.

[TarHeelTom]

That's not a bad idea - it is a rather old machine, and if I've found these problems, the oil system is probably suspect in other places too.

However, I'll probably just check them first to see if they're clogged. No sense in fixing what isn't broken. They're probably very mechanically simple - a precise hole to restrict fluid for a given pressure. Assuming I have the right drill or wire diameter, or perhaps even a solvent like carb-cleaner, I can probably clean them rather than replace them.
Torin...

Pay heed to what Al said. Replace all the metering units. I'm rehabbing a Bridgeport. The book tells me there are 8 fuel metering units. I've found 21 so far. Had to replace 20 of them. I'm not an expert, but I've read several others say that they are difficult or impossible to clean, and you certainly don't want to attempt to run a piece of wire through them. Only thing I might possible try would be an ultrasonic cleaner and solvent for many hours.

The fuel metering units are cheap. The alternative is to have the ways reground and scraped. And that ain't cheap.

Tom

[torinwalker]

Ah... you guys are right. I have the schematics for the original lube system (the CNC 605 center drawings) as well as the original manual for a 602 system. Between the two, and looking at the machine, of course, I'll just bite the bullet and replace them all.

How much did you pay for these little guys? I'm guessing $5 each, perhaps more, right?

Say, while we're on the subject, did either of you guys do anything to the lines themselves? Did they need to be cleaned, or were they in good shape?

[TarHeelTom]

Ah... you guys are right. I have the schematics for the original lube system (the CNC 605 center drawings) as well as the original manual for a 602 system. Between the two, and looking at the machine, of course, I'll just bite the bullet and replace them all.

How much did you pay for these little guys? I'm guessing $5 each, perhaps more, right?

Say, while we're on the subject, did either of you guys do anything to the lines themselves? Did they need to be cleaned, or were they in good shape?

I paid about $9 each from Bridgeport Mill Parts- Servo Power Feeds-Icai-Online.com

Did nothing to lines, except add one line to move the oil pressure gage to a remote location on the head. My mill has almost all copper lines running to the lube metering units, and mixed bag of plastic and copper from the lube metering units to the delivery points.

One of the repairmen suggested that he fills the lube tank with solvent and lets it run almost dry, then fills it with lube again. Probably not a bad practice.

I suspect that there is a world of difference between a mill running 24/7 in a production environment, and one running sporadically in a home shop environment. Suspect that the lube oil contains a lot of wax to keep it in place on the ways, and that this may tend to turn to gel or solid over time. But I'm not an expert on this.

Tom