View Full Version : Lathe cross slide oil grooves

Virgil Johnson
09-02-2006, 12:41 AM
I have a new lathe that does not have oil grooves on the underside of the cross slide or a good way to get oil there for that matter. The bearing surface on the slide is approx. 1” wide and 16” long. I plan on milling a groove with a 4mm ball end mill .03-.04 deep starting 1/8 from the edge and end of the slide at a 9 deg angle from the side (vise rotated 9 deg. on mill) milling to within 1/8 in. of the opposite edge, rotating the vise in the opposite direction and repeating the process 3 times. This will form a “zig zag” groove down the slide. I plan on drilling a hole through to the top and adding a “zerk” type press in oil fitting. Any thoughts on the modification? Waste of time? Bad idea? The manufacturer did offer to mill oil grooves for me but I’ll be without a lathe for 2-3 weeks if I have them do the job. Thanks.

J Tiers
09-02-2006, 12:49 AM
Could be an OK idea.... just remember to scrape off the burrs.

I did something similar to my Logan, but involving oilers for the carriage on the ways.

And, I'd stay further from the edge.... 1/4 inch or so. It will be fine, the oil will get there and not leak out so fast.

I would also scrape the edges of the groove to a "lead-in" slope, to encourage the oil to "wipe onto" the surface, instead of a hard edge that could tend to scrape it off.

09-02-2006, 01:10 AM
I've got similar issues for my Rockwell. I just got VERY lucky in finding a replacement in good shape to replace my completely junked cross and saddle. The galling was so bad, it was hopeless. Seemed to be a problem with both lack of lube AND contamination.

My thoughts on correcting this are two fold...

1) Add a high pressure fitting (zirk/alemite/whatever - flush or otherwise) and some sort of channel as you propose. Wouldn't take much and I wouldn't want to reduce bearing surface on mine, which is not nearly as big as yours. FWIW, I think a very shallow trough cut with a 1/8" ball end is in my future with the fitting dropping in on it from the top. This would allow you to force in way lube just like the old Bridgeports (already have the converted grease gun) to flush out contaminates and "load" the reservoir. I'm also adding these high pressure way lube fitting to the saddle.

2) Why don't more lathes have wipers and other measures to protect the cross slide? I've looked at some more high end machines and notice that they DO have elements to help eliminate contaminates. I'm thinking a wiper at the least. I also noticed that on lathes like the Moriseki they have a trough on the saddle down the sides of the cross slide ways that acts as a channel to divert coolant and such that would carry contaminates onto/into the ways. Others have raised cross slide ways. On the Rockwell and many others, the design is really bad in that the cross slide ways are level with the apron and offer nothing to divert contaminates. I’m thinking I may just put wipers on my new cross slide at the least. I don’t use flood, so the side protection is not as critical, though that could be addressed with trough or some sort of side dam (like long felt wipers on the side?).

09-02-2006, 01:55 AM
I don't see any issues with drillng down to where you need oil. I would chamfer and smooth the bottom of the hole and probably add a cup at the top with some felt inside to "meter" the oil flow.

I would caution against reducing the bearing surface area with anything other than scraping marks or flake marks to hold oil. Longivity will be extended by maximizing the oil film between parts.

Virgil Johnson
09-02-2006, 07:07 AM
Thanks for the replies so far. The machine has wipers and a trough around the ways to drain coolant away. In the current design the oil maust wick down the dovetail from the factory provided fitting. There is a relief groove milled at the corner of the dovetail on the saddle which acts as a drain to the oil as it comes down the dovetail. The builder did not seemed too concerned as they do not have these on their 14" machines. This is not the cheapest lathe I could find so I'm a little leary of questioning their engineering. A .157 dia ball end mill @ .03 deep cuts .122 wide. After doing the math on the bearing surface I may use a .093 dia. @ .01-.02 deep.

09-02-2006, 09:51 AM
I'd also prefer not to reduce bearing area. The other thing that oil grooves can do is collect abrasive materials, leading to a bit more wear adjacent to the groove. Of course, the liberal use of oil should keep it washed out.

The cross slide on my Harrison 13" lathe has only a single hole on each slide, strategically placed ;) The one shot oiler on the apron pumps oil here and numerous other places. The oil does distribute itself nicely as the slide travels in and out. Den

J Tiers
09-02-2006, 10:15 AM
I would NOT be concerned with the tiny reduction in bearing area from a small groove.

The oil groove is a common feature on machines, and actual area reduction is very small.

Then also, which would you pick from teh following:
A couple percent area reduction but good oil flow?
Very poor oiling but 2% more bearing area?

I know my pick... already DID pick that. And I like it. The oil flows OUT washing out any contaminants. Where it is common to see a grayish-black smear in the oil where there is no oil supplied under the part, (so it must "wash in", carrying dirt with it) with supplied oil the oil comes out clean.

Forrest Addy
09-02-2006, 12:19 PM
Don't worry about an oil distribution groove in this application. If oil can get to it oil, will find a way to infiltrate every crevice. Oil grooves are necessary for surface grinder tables and other rapidly moving way bearings but strictly optional for a slow, limited travel application like a lathe's cross slide.

It's more of a warm fuzzy feature than one required by enumerating operating conditions in the light of past industry experience.

09-02-2006, 03:05 PM
I was thinking of the groove/trough running length wise down the way with the oiler port more or less in the center. Then when it gets a shot of oil, the trough is the path of least resistance carrying it front to rear, and then out into the bearing surface somewhat evenly (in an ideal world). Without it, I imagine much of it would simply disperse straight out the side.

Of course there will still be some on the bearing, it’s not like all is going straight out the side. And no doubt there will be much more in there than the factory designed perimeter oiling, so maybe I’m just over thinking it.

In any case, sounds like Virgil has one of the nicer lathes I was mentioning that comes with the features I’m thinking of adding to mine, so my comments are irrelevant...

09-02-2006, 03:37 PM
With a single longitudinal groove, the oil will tend to fill up the groove and flow to the ends without providing consistent coverage of the flat metal plane provided as a bearing surface. The groove will act as a drain, not a reservoir.

Wear will occur until the metal to metal surfaces are worn down to the level of the induced groove where, once again, the oil can be squished evenly along the flats.

Unless you have high speed rotational wiping to distribute the oil evenly over the plane (similar to a crank journal), I would doubt much benefit, and perhaps increased wear, with a longitudinal channel for the oil to flow into. You will not see consistent oil coverage of the plane without frequent flooding with this modification.

You would be better off by milling several x's to allow a wiping action.

Virgil Johnson
09-02-2006, 04:00 PM
Thanks for the replies/help. I think I will quit trying to re-engineer this thing and make some chips. When I was setting up the machine there were some chips in the groove which holds the compound T-nuts which I cleaned out by removing the cross slide. Thats when I started looking at the oiling system. Speaking of oil I found a "recipe" for home brew way oil....gotta get me a bat's wing, some STP, mineral spirits.........:-)

09-02-2006, 04:50 PM
Thanks Larry, great explanation, I hadn't considered it that way. :o I'm still not entirely sure I understand how the oil would behave, but I don't want to take a chance of making things worse. So I'll just limit my mods to adding the pressurized oiling port and wipers (which I'm sure will be an improvement) and avoid modifying the bearing surface. These things lasted for decades in professional shops so it's not like it will fail overnight in mine if I changed nothing...

Good luck Virgil, your post was very timely. :D

J Tiers
09-03-2006, 01:37 AM
Youse guys can armchair engineer it all you want....


No, the oil is not all pressed into the groove.

Yes, the oil gets spread out all over.

No, it does NOT function as a drain.... why would it? After all, there is ALREADY a drain just like it, only bigger, and totally free-flowing, all around the edge of the slide.... If the oil does not come running out of that, screaming, it isn't all gonna drain into your already-oil-filled groove.

No, it will not cause the slide to wear down to the bottom of the groove and then start working "right" again.

You do NOT need a high velocity to spread out the oil.... all you need is to scrape a rounded edge on your groove.... the oil will wipe out under that and do just fine.

Mine works fine, and so will yours. As soon as I had done the work, I immediately noticed that the parts had begun to feel "oiled" in the way they moved.... unlike the typical previous "sticky" feel of them. Then the dark abrasive "goo" that had been under there gradually got washed out. And, mind you, I had cleaned the slideways prior to re-assembly. But there was STILL some of the previous "goo" stuck in there. The oil washed it out with the new system.

Now, if you had already had some form of oil entry under the slides, I would not be so insistent. But given that you do not, per your 1st post, it could pay to add it.

And, BTW, Cincinnatti did exactly what you are proposing to do, on the saddles of their tray-top style lathes. Probably on others as well, but those are the only ones I happen to know about.

Virgil Johnson
09-03-2006, 09:05 AM
J. Thanks for your reply. My lathe will see 2-3 hours use per week on a busy week. If this thing were going to be operated in the environment where I have worked in the past I would be out there milling the grooves and adding additional oil fittings this morning. (flood coolant, constant chip slurry) After thinking about it yesterday I decided not to modify it when I considered the actual usage time. Since the builder (not really the builder but distributor) had not done this modification before I decided not to send it back to them as they would be guessing how to do this as I would be. Don't want them learning on my lathe :-) My XLO mill has a similar (as does Bridgeport, Parker majestic surface grinders) oil groove pattern on the saddle and was worn only .0015 at the end of the saddle after 30 yrs use so I don't think the grooves would make it wear faster or drain the oil. Just overkill in my case. thanks again.

09-03-2006, 03:09 PM
Yes, thanks for the real world experience J.

However, like Virgil, I think I've decided not to do the groove. I don't use flood, and with legions of these lathes out there lasting for many years in production shops (and schools, homes, etc.), I think that the simple addition of forced lube injected deep into the dovetail area will be more than sufficient for my needs. Given the complexity of fluid/hydro dynamics including non-intuitive/obvious behaviors and other considerations beyond my knowledge (or interest in investigating) I’m going to avoid the distribution groove.

IMO (of the moment), the oil port for getting plenty of oil under there along with the “flushing” action is by far the most important improvement. Eliminating the groove means less work for something that will arguably provide only incremental improvement (at best) that could probably be classified as “overkill” while introducing potential unforeseen effects.

J Tiers
09-03-2006, 11:14 PM
Absolutely... if you have, or put in, a means for getting oil in there, then the groove is secondary.

The problem is when oil can only get in teh ends.... which are dirty. Then you KNOW that oil will wash gunk in.

With fresh oil supplied from within, the gunk goes OUT...

09-03-2006, 11:42 PM
I just finished adding the oil holes and fittings. The results so far are mixed.

Seems the cross slide fits so snuggly to the saddle when the gibs are firmed up, that the oil can’t really get out of the hole, particularly on the gib side. I had made only a 1/8” hole through with the 1/4” tap on top, and then tapered the hole fore and aft about 1/8” using a Dremel and small stone to cut a shallow trough and blend the edges. When this didn’t put down the oil like I wanted, I changed plans and re-drilled the lower hole out to a #7 matching the top tapped hole and then blended that one a bit further. This works better, but still does not "flush" like I had wanted. But it does form something of a reservoir and works well enough as I cycle it back an forth, you can definitely see the additional oil working out.

I may revisit later to see if I can find a way to make it “flush” out as originally planned. Maybe adding wipers at the same time.

J Tiers
09-04-2006, 12:14 AM
If oil is working in, you are good to go.

If you COULD flush it, your clearances would be too big. The slide would float up, and then settle back as the oil pressed out somewhat until the film was thin enough to resist flow.

That is the fallacy of the "squeeze-out" theory. Oil in a thin film does not flow easily, it sticks to its surfaces. It's HARD to make it flow with pressure. But those thinner films are just fine with large area bearings moving slow.

So having more oil available is what you want. It will flow out at the rate it wants.

Don't forget that the bottom surface AND the dovetail both want oil. It's harder to get it to the dovetail.

09-04-2006, 01:59 PM
Youse guys can armchair engineer it all you want....

And, BTW, Cincinnatti did exactly what you are proposing to do, on the saddles of their tray-top style lathes. Probably on others as well, but those are the only ones I happen to know about.

Agree with J Tiers -- I've seen and used machines with oil grooves cut on the underside of the saddle, and it works great. In fact, most Bridgeports have a sinusoidal oil groove cut on the underside of the saddle.

Free-handing a sinusoid with a Dremel is a pain, but you can also cut a diagonal groove with the saddle mounted on a milling machine, with perpendicular grooves at regular intervals. Just make sure the grooves don't extend past the edge of the box ways, or you'll leak oil.

Here's an article from the September 16, 1966 Model Engineer that's posted on the Yahoo mlathemods2 group that shows the straight diagonal oil groove pattern cut into a Myford Super 7 saddle:


Peter N
09-04-2006, 02:36 PM
Here's an article from the September 16, 1966 Model Engineer that's posted on the Yahoo mlathemods2 group that shows the straight diagonal oil groove pattern cut into a Myford Super 7 saddle:

Here's a picture of mine just in case you can't log into the above group.



09-04-2006, 02:42 PM
Here's a picture of mine just in case you can't log into the above group.

Nice job Peter!

Peter N
09-04-2006, 02:55 PM
Thanks Lazlo. It looked like a ploughed field before I ground it, so I was pleasantly surprised to find it only needed 0.007" off to bring it back to how it is now.