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View Full Version : Taig z-axis leadscrew oil showing metal flake



MechanoMan
04-19-2009, 12:31 AM
I've been using ATF so far for the leadscrews and slides.
It doesn't seem to want to stay on the leadscrew well, esp not above 40ipm.

I was having a look at he ATF that puddled off the Z-axis leadscrew onto the y-axis way cover. I was alarmed to realize its cloudy look was actually a metallic "sheen". I took one of my super-strong N48 magnets and found the fluid was attracted, in fact it dripped upward like 1/8" at it. Fresh fluid did not do this.

OK maybe it was from "the work", although there's not been much I've done with ferrous metals which would be attracted by a magnet. I cleaned the screw, ran it to the bottom, poured a load of ATF from the top all down the Z-axis leadscrew, ran the headstock up slowly, cleaned the puddle off the way cover. Repeat.

Still has metal flakes in the fresh fluid. Wondered if I totally overtightented the leadnut. Disassembled, backed off the 2 side screws on the leadnut like 3/16 of a turn, tightened the center locking screw, repeated cleaning procedure. There is now a perceivable backlash- when I lift the headstock, it rocks up just a teeny click. At this point I have the motor off and will not be reattaching it for the rest of what I'm talking through here.

Again, forms metal flakes. So I've cleaned the leadscrew here, I'm adding fresh fluid, giving it a chance to "take" into the nut, rinse with more ATF, but I keep seeing this metal sheen and it's attracted by a magnet.

I'm beginning to think the ATF is a horrible choice for lube. But I cleaned it and tried some 30W chainsaw bar-and-chain oil, but again, it's shimmering with metal. Looks like not nearly as much as the ATF but that's hard to compare subjectively, the fluid color alone can throw that off, and the amount of fluid added and the number of runs before it dripped off was inconsistent.

Am I right to be alarmed, or is this somehow normal?

But the 30W stays on the screw MUCH better. I see that. It takes more speed to sling off, doesn't drip as fast, and I can see a thicker layer lingering on the leadscrew.

Jeff-Birt
04-19-2009, 08:16 AM
Why not use a lubricant made for the purpose? You might have better luck with Mobile Vactra #2.

fretsman
04-19-2009, 08:36 AM
Not sure about the metal flakes in the oil but some stay with the ATF for vicosity reasons as way lube can thicken in colder temperatures and bog down the axis. I never experienced this as I've used ATF the whole time and haven't had any issues. The ATF sticks to my screws just fine through 60IPM rapids.

What I'm not sure I understand is why would you have magnetic shavings to begin with? It's a Cr-Mo leadscrew with a split bronze nut, so wouldn't the nut be wearing in the first place?

Dave

MechanoMan
04-20-2009, 04:35 AM
Good question! Wouldn't the bronze leadnut lose material before the steek leadscrew? But apparently not. I am certain the drippings are directly off the leadscrew and the flake is fresh.

Is your ATF dripping totally fresh, or slightly black? If you put a paper towel against the axis, press it into the groove with a fingernail, and run the axis a bit, do you get fresh-looking ATF or darkened?

Got a big magnet? Try it- clean the way cover, run your axis down, give it some extra ATF, run the axis up and down and check the drippings. BE CAREFUL, I had that magnet jump out of my fingers onto the rail for the Z axis. Didn't scratch the rails and my fingers didn't get pinched fortunately.

It was really weird. As I brought the magnet close-up, I thought I was seeing the glare of the desklamp off the chromed magnet surface. It was a bright shiny line reflecting off the fluid that turned with the magnet. But some of its reactions seemed "off" for glare. I gripped it in my hand so there was no shine off the magnet, but the fluid still showed a bright line which rotated and danced along with it!

Kinda freaky to look at actually. And seeing it drip upwards was something else.

Hirudin
04-20-2009, 10:38 AM
Good question! Wouldn't the bronze leadnut lose material before the steek leadscrew? But apparently not. I am certain the drippings are directly off the leadscrew and the flake is fresh.

Is your ATF dripping totally fresh, or slightly black? If you put a paper towel against the axis, press it into the groove with a fingernail, and run the axis a bit, do you get fresh-looking ATF or darkened?

Got a big magnet? Try it- clean the way cover, run your axis down, give it some extra ATF, run the axis up and down and check the drippings. BE CAREFUL, I had that magnet jump out of my fingers onto the rail for the Z axis. Didn't scratch the rails and my fingers didn't get pinched fortunately.

It was really weird. As I brought the magnet close-up, I thought I was seeing the glare of the desklamp off the chromed magnet surface. It was a bright shiny line reflecting off the fluid that turned with the magnet. But some of its reactions seemed "off" for glare. I gripped it in my hand so there was no shine off the magnet, but the fluid still showed a bright line which rotated and danced along with it!

Kinda freaky to look at actually. And seeing it drip upwards was something else.
I'm using Vactra 2 and my oil comes off looking very dark.
I got it from Enco (http://www.use-enco.com/CGI/INSRIT?PMAKA=505-1987&PMPXNO=945479&PARTPG=INLMK32) by the way, it's pretty cheap if you ask me...
After that trippy description I'm going to have to see if my neodymium magnets are powerful enough to get similar effects.

fretsman
04-21-2009, 05:19 AM
Ok, had a look yesterday but it's going to be a little bit of an unfair test as I have been using my machine in my shop for about a year and a half and there's a lot of metal "dust" flying around as I work with a lot of aluminum.

I cleaned off the screw as best I could for you and flushed the Z screw and nut with ATF, and while the ATF is a darker color than when applied, it's not black with metal flakes. I tried pulling it with a magnet and got no movement.

Sorry-
Dave

mrscheider
04-25-2009, 08:51 AM
Hi All,
For whats it's worth, I've been using ATF on this machine for a little over a year. Love the viscosity. Sticks well, but it's a black as dirty motor oil when it comes off. In another post I was discussing a stripped leadscrew, and while disassembling the table, the sludgy fluid is all black and nasty. I use Castrol which has a pinkish appearence when it goes on so I dunno whats mixing in to blacken it. Good news though, no steel flakes. Just aluminum and brass from previous work.
Hope this helps.

Mike

MechanoMan
04-26-2009, 03:50 AM
Hi All,
For whats it's worth, I've been using ATF on this machine for a little over a year. Love the viscosity. Sticks well, but it's a black as dirty motor oil when it comes off. In another post I was discussing a stripped leadscrew, and while disassembling the table, the sludgy fluid is all black and nasty. I use Castrol which has a pinkish appearence when it goes on so I dunno whats mixing in to blacken it. Good news though, no steel flakes. Just aluminum and brass from previous work.
Hope this helps.

Mike

Well, ATF cannot turn black from oxidation or absorbing moisture. The only thing which blackens it is foreign material. Aluminum wouldn't do it and probably not brass either. Aluminum can't be black, and milling operations never reduce the metal to this sort of soluble dust. So, yeah, I think you've got steel from the leadscrew in the lube.

I probably should not have used the term "flake". This is metal particles, a very fine dust in the fluid. I need to try to take a pic or video showing what I'm describing but it'll need to do some major close-up work to show it.

I had some black used motor oil waiting to be recycled and checked it with the same magnet. Interestingly enough, no, it's not attracted to the same magnet.

I'm not seeing how ATF could be described as "sticks well". The stuff runs off pretty easily. That's Dextron-III I'm using and I don't expect brands to have any obvious, remarkable differences, since it wouldn't meet the common spec they share. The 30W is looking much better. It sticks to the leadscrew over repeated runs really well.

fretsman
04-26-2009, 08:22 AM
I'm not into forum pissing contests but I will say this and be done here.

I've been a manual Machinist then Toolmaker for over 24 years now and I use aluminum and brass all the time, and yes, it does make fluids turn black. Whether it's atf or tapmatic aluminum cutting fluid or whatever, it does indeed turn it black when it's been used in machining.

Or at the very least, a very dark gray since we're splitting hairs. :)

Dave

mrscheider
04-26-2009, 08:27 PM
Mechanoman,

Obviously, with my leadscrew stripped there is metal in my fluid. :)
But that was only in the Y axis. I tried the magnet test on the fluids floating around in the X ways and that didnt have any steel in it that I could find and that was dark too, maybe dark grey.. but mostly black.. and gooey!
I wiped it down with a paper towel and it was clearly thick. Much thicker than how it goes on... which leads me to the ATF. Yes, it runs right off my stuff too, but I dont put enought to drip off. I meant it sticks well because the machine stays well lubricated hours into a job. Its certainly not thin enough, at least in my experience, to fling off the leadscrew if I apply it while the screw is spinning. I've only used a couple other lubes but Im open to try anything that will work better than the ATF. So far, it's the one that seems to work best for me.
Kind regards,

Mike