A One Shot Oiling System for the Industrial Hobbies Mill

As part of my CNC conversion of the mill I want to engineer a one shot oiling system. It will increase the reliability of the mill and ensure smoother operation.

Raw Materials

Vinyl oil-proof tubing. 100' roll, cost $20 on eBay. Box of Legris push-on fittings and some Parker Flow Control Valves from eBay. One shot oil pump, slightly used, still in good working order. Collection of brass manifolds from eBay.

eBay provides all the components needed to create a one shot oiling system...

Close up on the Legris fitting and Flow Control Valve:

Flow Control Valves have a check valve in them so the oil can only flow one way. It's convenient to build that in with a valve so I can fine tune how much way oil is going to each lube circuit. The IH mill will need the following lube circuits:

X Axis: Left & Right Ways, Ballnut

Y Axis: Left & Right Ways, Ballnut

Z-Axis: Left & Right Ways, Ballnut

For a total of 9 circuits. In terms of fittings, this means 9 fittings to thread into the base castings, 9 check valves, and a manifold with associated piping. There will also need to be a couple of fittings and tubing to connect the pump to the manifold.

Z-Axis Modifications

I started out this project modifying the Z-axis. I used a 1/8" ball mill to cut oil distribution grooves on either side:

Here I'm cutting the two long angled grooves. The intersect the existing oil passages, which I'll use to inject the oil...

I assembled the Z-slide on the column with gib and just injected through the existing ball ports to see how they worked. Oil distribution was excellent! There was immediately a nice even layer of oil laid down over the entire width of the ways. The slide became noticeably easier to slide even with the gib set tight. I think I'm going to like this new setup!

The Y-aixs. I had a couple of minor issues. I got a little too exuberant on the feed and broke an endmill. Left no impact on the slide groove at all, but it damaged my collet slightly. Bummer! Second issue is that I ran out of travel and had to shift the table to drill the second groove set.

Last set of grooves for the X-axis. Be sure to avoid the hole in the middle of the bottom way. That's for access to an additional mounting bolt for the Y-axis nut.

Here's the 1/8" ball end mill and a little closer look at the grooves. BTW, after breaking my 3rd end mill, I got suspicious of the ER-32 collet chuck I had been using. It's a real cheapie, and I suspected it had excessive runout, which will snap these delicate little cutters. A fixed amount of runout gets to be a greater and greater percentage of the cutter diameter as you get small, hence the stresses get worse even if you're prepared to live with the inaccuracy. I dug out my 1/8" R8 collet and nary a problem was had. 2 new Bison ER32 collet chucks are on order!

The grooves are now cut for all axes. Remaining work on the ways includes drilling the holes that will connect the grooves to the fittings, engineering and fabricating the delivery of lube to the ball nuts, and any remaining mounting brackets.

Plumbing to the Grooves

First line up on the old ball oiler location with a spud. On the Z-axis, this hole goes all the way through already (nice!). So we just get rid of the ball oiler (mine had to be drilled out)...

And now drill the hole you'll tap for the fitting...

And tap. That fitting will be in the way of the gib locks, but I won't be using them anyway. I will likely put bolts of the same size into the holes to block them off...

Bit leaves a nasty bottom in the cast iron doesn't it?

The saddle has no handy holes to work from. I'm drilling at the intersection of the middle cross grooves and centerline groove. The saddle is held by gently opening the Kurt vise with aluminum jaws against the ways. All holes are 0.450" deep.

With both sides drilled, it's time for the cross passages. My 6" Kurt was too big, so I took it off the table and installed my 4" Kurt. The vise has to fit between the X-axis slides that stick out...

I just lined up visually. It's actually closer than this, a bit of parallax from the camera angle makes it confusing...

Drill this hole all the way through from the outside to inside the ways so oil can get inside the dovetail. You can tell the holes line up if swarf comes out the cross hole!

Swap bits (almost not enough vertical room with my big keyless chuck!) and drill the fitting hole you will tap...

The X-axis goes pretty much the same as the Y-axis did. Be careful about putting the fitting too close to the center--that's where the limit switch mounts. You can also go in from behind as Thomas Powell did. It will make for a neater installation, but I had doubts about my ability to tap the fitting holes with so little clearance, so my fittings are all on the outside.

Did some thinking about how I'll run the tubing. Essentially I plan to put in two manifolds--one on the X-Y saddle and one on the Z-axis saddle. Attached to the manifolds will be the flow control valves so I can individually meter each passage for the proper amount of oil. I'll mount the one shot pump on the mill column and use flexible tubing to connect to each manifold so that these two tubes are the only ones moving--the rest of the plumbing is fixed. Access to the X-axis ballnut is easy as there is a large under-table gap. I may drill a hole through the saddle to allow flex hose to go underneath for the Y-axis ballnut. Same with the Z-axis ballnut. So, we'll have a 6-port manifold on the X-Y saddle and a 3-port on the Z-axis saddle.

X-Y Manifold and Plumbing

I wound up making a manifold, and as it was a long piece of alumimum rod needing a center hole all the way through, I needed a bit longer than I had on hand. So, I used it as an excuse to try my hand at a homemade D-bit:

A D-Bit I made to bore the center hole in the manifold...

It cut fine, but loaded up with chips so fast it was a very slow process of having to withdraw every quarter inch or so to remove the chips. It seemed like it took hours, though it was probably only an hour and a half. Next time I'm ordering an extra long twist drill!

I took a 3/4" endmill and made cuts, then drilled with 7/16"...

Since my tap wrench isn't big enough for this chunky 1/4" NPT tap, I used a machinist's parallel clamp...

Both ends are drilled and tapped in the lathe as well!

Here's what the manifold looks like trial fitted with the flow control valves and Legris push-on ells. I'll be using translucent tubing so I can verify visually that the oil is flowing...

A little broader view. There is a Legris on the back side of the saddle that goes to the top left flow valve. The valve right below it will be plumbed up to the ball screw lube port you see on the ball screw mount. I added that port!

Clear tubing makes it easier to monitor the oil. I adjusted valves until the oil was arriving everywhere at about the same time...

Excuse the clutter, but here is a better view of the finished X-Y oiling system...

Between having lapped the ways and installed this one shot system, I can turn the ballscrews and motion is velvety smooth even when I've got the gibs as tight as they'll go with a screwdriver!

Working on the oil pump mounting plate on the column:

I had to make a set of transfer screws to pick up the bolt holes for the pump. Full details here...

Here's what the finished pump mounting looks like. The front line goes to the saddle. The rear line goes to the little manifold which has a vinyl tubing connection for either way on the Z saddle and the copper tubing goes up to oil the ballscrew. The rear circuit would benefit from a flow control valve, but I ran out of fittings. The flow control valve has two benefits. First, the check valve would keep the line charged so there'd be no need to pump oil up so far. Second, the current circuit flows a little too freely relative to the other circuit, so I get a bit more oil on this circuit than I'd like. It isn't terrible, so I don't know if I'll fix it or not...

I reused the original oiling hole for the ballscrew oiling. I turned a little press fit piece of aluminum and JB welded the copper tubing into the proper position. The oil flows out onto the top of the ballscrew where it can drain down through the grooves all the way to the ballnut...

While a little change here or there might improve the system (for example, a flow control on the Z-axis circuit), I am calling the one shot oiler done. It works extremely well and will give me a lot of peace of mind about the mill's durability and proper oiling. It was well worth the amount of effort I've invested in the project.

Project Planning

This modification has been done by Thomas Powell on his IH mill.

It's all mounted on the saddle. Lines into saddle feed Y-axis ways, X-axis ways, and X-axis ballscrew. The 4 lines going the opposite way feed the Z-axis ways, Z-axis ballscrew, and Y-axis ballscrew. Oil comes in via the heavy black hose from the pump...

Thomas mentions he wishes he had cut some oil channels into the ways. Now that I own 2 IH mills, I can use one to cut the grooves in the other with a small ball mill. If I didn't have a second mill and was desperate to have some grooves in the ways, I guess I would try to design a fixture that slid along the ways with a high speed spindle and stone attached to do the job. The other thought is to just run a little CNC program that moves the machine axes to spread the oil while the pump lever is pulled a few times. This would be a "warm up" sequence for the machine to run at the beginning of each session.

The consensus seems to be that 1/4" tubing will work well for this sort of thing. If the tubing doesn't move, some folks like to use stainless tubing.

Mxtras one shot lube system on his Bridgeport...

Thoughts:

- One shot on a Bridgeport: He used Bijur B1114 metering valves, an 8 port manifold bought from Enco, and 1/4" tubing (some stainless, some flexible plastic).

- Nice thread on one shot systems on CNC Zone.

- One shot lube system on Bridgeports.

- Mxtras one shot system on a Bridgeport.

- Kay Fisher does a one shot system on a Bridgeport

Mxtras and others like Thomas Powell have used Legris 3109 series push lock pneumatic fittings. Mxtras says that in retrospect, he wishes he had check valves, and suggests using air flow control valves, which have built in check valves. He is planning to fit Part #7065 56 11 (1/8"NPT, 1/4" tube) Legris quick connect flow control valves. McMaster-Carr lists flow control valves (62005K224), but they are $17 each!

The IH mill will need the following lube circuits:

X Axis: Left & Right Ways, Ballnut

Y Axis: Left & Right Ways, Ballnut

Z-Axis: Left & Right Ways, Ballnut

For a total of 9 circuits. In terms of fittings, this means 9 fittings to thread into the base castings, 9 check valves, and a manifold with associated piping. There will also need to be a couple of fittings and tubing to connect the pump to the manifold.