Need help converting Bridgeport Zerks to One-Shot-Oiler

[kdtop]

Hey all,

I am refurbishing a Bridgeport mill, and I want to convert the older-style oil zerks to a newer one-shot oiler. So I bought an oiler that looks like this one from Ebay:



And specifically has the connectors which are supposed to screw into the Bridgeport that looks like this (I measure this at metric 5.7 mm x 1 mm pitch -- probably supposed to be M6 x 1):



Unfortunately, I didn't catch that this connector thread would be different from the ones from my Bridgeport that look like this:

So what I need is an adapter. Something like this:



So my goal is to figure out the specifications of the original threads and the new threads, and see if I can purchase or manufacture a connector.

I have tried to figure out the threads of the original zerks. I notice that the thread is tapered. And with my thread gauge, it seems to be about 28 TPI, though it doesn't fit at neatly as I would like. Perhaps the thread profile is different. At it's widest, I measure 0.400", and it narrows to 0.365" at the base. So I am wondering if this is a NPT pipe style thread. I found this link: https://www.engineersedge.com/hardware/taper-pipe-threads.htm which lists an NPT "1/8"-27 thread with external diameter of 0.405".



I also found this zerk set here:

which shows zerks that are SAE or PTF type threads.

And this chart from here shows various SAE, and NPTF fittings:

I am thinking if I could get a grease fitting cap, that I could then tap this for the M6x1 thread to make an adapter. I found here a plug for 1/8-27 PTF that might work.

As an additional complication, this is the location of the zerks on the front of my saddle (stripped of paint)



This is going to be very awkward to have oil tubes sticking out before curving back to the hub. I am going to see if I could cap these off and connect a new channel from inside.


QUESTIONS:

• Does anyone know the nominal specifications or dimensions, or thread style of the oil zerks used in Bridgeport mills?
• Has anyone seen any adapters such as I am looking for already made up?
• Any recommendations for options for those front-facing oil ports?
• Any other recommendations?

Thanks in advance,

Kevin T

 

[woodchucker]

just buy new connectors, they are not expensive. Match it to your threads and the tubing size. Many sell them. and they sell 90 degree ones as well.

 

[kdtop]

just buy new connectors, they are not expensive. Match it to your threads and the tubing size. Many sell them.

These new connectors seem to be the "shark bite" type connectors. I.e. you push the plastic tube in. Doesn't seem to have a ferrule like older systems. Do you happen to know what these are called if I were to search for them? I.e. I don't know how or where to buy new connectors.
Thanks for your help.

Kevin

 

[kdtop]

These new connectors seem to be the "shark bite" type connectors. I.e. you push the plastic tube in. Doesn't seem to have a ferrule like older systems. Do you happen to know what these are called if I were to search for them? I.e. I don't know how or where to buy new connectors.
Thanks for your help.

Kevin

Looks like "push to connect" is the key search term.

If I search "1/8 npt push to connect", I get many options on Amazon. Now I need to see if the tubing my system will be a correct size for them. Seems imperial fittings want imperial sized tubing. Any this Ebay oiler is metric. I'll have to measure the tubing later when I have time to get back to the shop.

 

[woodchucker]

Looks like "push to connect" is the key search term.

If I search "1/8 npt push to connect", I get many options on Amazon. Now I need to see if the tubing my system will be a correct size for them. Seems imperial fittings want imperial sized tubing. Any this Ebay oiler is metric. I'll have to measure the tubing later when I have time to get back to the shop.

don't rely on it being imperial. Also be aware that some that are marked NPT are really British either Whitworth or BSP can't remember.

 

[kdtop]

don't rely on it being imperial. Also be aware that some that are marked NPT are really British either Whitworth or BSP can't remember.

Why can't we all just agree to one standard?? (I know, I know)....

More info I have figured out:
It looks like the metric systems use 4 mm, which would be 0.157". 1/8" tubing is the imperial value that is similar to this, but it is only 0.125", or 0.032" smaller. Amazon does sell 5/32 connections to the 1/8 NPT connectors. 5/32" = 0.156", or essentially the same as 4 mm. It is not clear to me if the same connectors can be used with both 1/8 and 5/32", but since none say this explicitly, I am not going to bet that it does. 32 thousandths would certainly be enough to make larger tubing not fit or smaller tubing leak.

And another confusing fact that I may have figured out is that 1/8" NPT thread is not referring to either the ID or the OD of the thread. Instead, it is simply a specification name -- apparently named for the tubing that it connects to. I was trying to figure out how a thread with OD of 0.405" was being called "1/8 inch", which would be only 0.125"!

 

[woodchucker]

you need a specific size .. a few cross over between metric and sae, but 1/32 diff might as well be a mile (I think).. Size does matter.

 

[Provincial]

Don't concern yourself about the reasoning behind the specification for 1/8" pipe thread. Just get fittings that have 1/8" male pipe threads so that they will match the holes Bridgeport tapped. If you want to hide the tubing, some new holes will need to be drilled and tapped. The old holes on the front of the saddle can be plugged with hollow head pipe plugs if you go that route.

The "push lock" fittings are very strong. There is a version that is rated for vehicle air brake systems, which tells you a lot about strength and durability. I believe that the major difference between commercial and air brake push lock fittings is certification, not physical strength or durability. In practice, 4mm and 5/32" are interchangeable. Check out Parker and Gates catalogs for information. Nylon tubing of a good grade is necessary if you want the tubing to handle the pressure the fittings are capable of.

There are videos on the internet that give advice on this modification.

The big variable that you need to consider is choosing the appropriate orifice size for each distribution line. Some need more restriction than others to keep from wasting oil and making a mess. This is covered in some of the videos.

The two weak points on the original system are: (1) the need to place the table in a specific position, remove the plug screw in the table, and drip oil onto the top of the feed nut casting, and (2) the use of zerk fittings tempts people to use grease for lubricant, which does a poor job for a whole host of reasons.

 

[Jake M]

Hey all,

I am refurbishing a Bridgeport mill, and I want to convert the older-style oil zerks to a newer one-shot oiler. So I bought an oiler that looks like this one from Eb
And specifically has the connectors which are supposed to screw into the Bridgeport that looks like this (I measure this at metric 5.7 mm x 1 mm pitch -- probably supposed to be M6 x 1):

Probably an intentional undersize thread. That'll allow a M6X1m thread. That'll fully screw into a straight threaded hole, or a tapered hole. Both are out there. Don't get too hung up on "exact" thread forms on things like this. There are usually some liberties taken to make the whole thing fit into a larger subsystem within the various systems of threads.

Unfortunately, I didn't catch that this connector thread would be different from the ones from my Bridgeport that look like this:

That's 1/8 NPT. Pipe is sized by the inside diameter, hence the seemingly oversized thread. As opposed to the tubes you will be using, as tubes are sized by the OD.

If you take the actual fitting (where the "grease gun" clips on) out of the adapter (the part that screwed into the Bridgeport), you'll probably find a quarter fine thread fitting. If you take a modern replacement, you might find that even on an SAE adapter, they've used a 6mm thread for the actual fitting.... It's hit and miss, there is NO standard.....

So what I need is an adapter. Something like this:


So my goal is to figure out the specifications of the original threads and the new threads, and see if I can purchase or manufacture a connector.

Mcmaster (and eBay, and Amazon....) have a plethora of adapters, and you'll find that the PTC fittings that came in your kit are quite commonly available and inexpensive (or expensive, depending on your needs), and replacing those fittings might be less expensive than making adapters. Of course, you'll want to evaluate the overall protrusion as well. You might be better off doing it yourself or buying in something that's molded to shape.

I have tried to figure out the threads of the original zerks. I notice that the thread is tapered. And with my thread gauge, it seems to be about 28 TPI, though it doesn't fit at neatly as I would like. Perhaps the thread profile is different. At it's widest, I measure 0.400", and it narrows to 0.365" at the base. So I am wondering if this is a NPT pipe style thread.

Yes, it is. The taper tends to be a bit steeper than a standard NPT dimension. Usually. Again, there are a LOT of liberties taken to make stuff just work anywhere you can physically screw it in.....

I also found this zerk set here:

which shows zerks that are SAE or PTF type threads.

And this chart from here shows various SAE, and NPTF fittings:

And then there's that. PTF should end up with a steeper taper than pipe threads. In practice....... what you get is a little less, just about the same taper that's sold as NPT...... But again, within the subsystems, it works. They seal on fewer threads, they seal dry, whether they're sold as dryseal or not. (It's kind of obsolete. It's hard to find a pipe thread that won't dryseal these days.....).

I am thinking if I could get a grease fitting cap, that I could then tap this for the M6x1 thread to make an adapter. I found here a plug for 1/8-27 PTF that might work.
This is going to be very awkward to have oil tubes sticking out before curving back to the hub. I am going to see if I could cap these off and connect a new channel from inside.

Consider this- What if you were to install a 3/8 npt street elbow. Probably brass, so it's plenty strong but will still break off clean if it gets bumped, the "stump" will extract easily if that ever happens, and bonus, it's got enough "squish" that with an oiled thread on assembly, (oil, not tape) you can get a full seal at a low enough torque, that you've still got a full turn of "clocking" to point it where you want to point.... The male end obviously into the mill, drive a pipe plug into the female end, which can trimmed flush or not, depending on the drive, then drill and thread that plug (already installed to the elbow) to suit the threads your PTC connectors (from the kit).

 

[mmcmdl]

They make those fittings in all sizes . Multiple thread options as well as tubing sizes . MSC supplies us at work with these as we use them everywhere . They do not leak but they do break when smacked . Simple to replace when they do break . 1/4" tubing is standard but they have 6mm which are blue in color and not black and orange . Some of our mechanics stick 1/4" tubing into 6mm fittings which can not be removed other than cutting the tube.