Thread: Bridgeport clone head lube etc.

Gday All.
I've currently got the head of my 1980's HAFCO Bridgeport clone apart to fix a few things.
The lubrication system leaves a bit to be desired I reckon.
This machine has been apart before I got it. The gear housing for the back gear assembly has had grease put into it which is pretty useless as on close examination I can see where the gears have been running pretty much dry. Once the grease has been squeezed out and built up on the housing there's no more lubrication for the gears.
I've been looking on the net and there appears to be two camps. Pro grease and pro oil.
My personal feeling is to go back to oil.

In the next section down in the head, there is a "worm gear cradle" This is for engaging the quill feed.
This part has an oil way cast into the top and they have even gone to the trouble of drilling oil holes from the oil way down to the bushes and the gear. The oil way and holes can be clearly seen in this pic.

feed select 001.jpg

The problem is that there is no way for oil to get into the oil way.

feed select 002.jpg


The gears have had grease slapped on them but when I pulled it out I could see these gears had also been running pretty dry.
I know I could just stick it back together with some grease again and it would probably outlast me, however the little bit of OCD I have will make this option really bug me.

Seriously thinking about installing another oil line to oil the "worm gear cradle" and the gears. Will have to do some measuring tomorrow.

Thoughts?

Peter

I would go with a NLGI 0 grease (like this https://www.sparesbox.com.au/part/ca...iABEgIG5_D_BwE), it is a lot runnier than the standard grease you get in a tube. We use it a bit at work because it tends not to stick to the walls of housings like normal NLGI 2 grease from a tube does.

more info on grease here https://www.skf.com/au/products/lubr...ata-of-greases

Just so happens that the head of my Supermax copy is still apart, thanks to the new toy interrupting that procedure. The Supermax is pretty much a dead nuts copy, with the exceptions that it apparently has slightly heavier castings, and instead of the stupid plastic bushes in the varispeed sheaves it uses much more sensible bronze bushes (which I'm very pleased about).

So with respect to the oiling channels in the feed cradle, this is what should be oiling it:

IMG_20201222_000852_591x1050.jpg

The oil cup on the front of the head feeds through to the hole with the allan key sticking out of it, which is directly above the cradle. Of course, depending on the manufacturer of yours, they may have copied the casting for the cradle without understanding the reason for it, and omitted the oil cup...

On the topic of grease in the back gears - mine has plenty of grease still in the teeth of the gears (never been apart in the ten years I've had it, who knows before that), so I don't think there's much wrong with the idea, providing enough grease is packed into the housing on assembly (see H&W machine repair videos on Youtube for how much they use). However, if you wanted to do something about it, the Supermax also has a grease zerk at the rear of the housing, which feeds directly into the back of the small back gear. Location again indicated by the allan key in the photo below.

IMG_20201222_001108_591x1050.jpg

I wouldn't personally fill it with oil - mine had a fair bit of oil built up inside the housing, and it was weeping down between the red cast section and the outer section, and drooling down the outside of the head from the seam between the parts all the way round. So if you go that way, I think you'd want to seal between those two castings with RTV silicone or similar.... Will still leak down between the large bull gear 'carrier' and the housing though over time, eventually giving you some extra spindle bearing oil I guess...

Mine's rather unlikely to go back together in the next few days since I'm having too much fun with the Graziano, so if you want any photos of some other part of the head let me know.

The original bp design is that oil trickles down to the spindle bearings and out. So unless you replace with sealed bearings make sure that can still happen.

Sent from my SM-G973F using Tapatalk

Originally Posted by Jekyll and Hyde

Just so happens that the head of my Supermax copy is still apart, thanks to the new toy interrupting that procedure. The Supermax is pretty much a dead nuts copy, with the exceptions that it apparently has slightly heavier castings, and instead of the stupid plastic bushes in the varispeed sheaves it uses much more sensible bronze bushes (which I'm very pleased about).

Mine is a step belt head ( which I didnt even think to mention in my original post - oops) Looking your pics there are some substantial differences between yours and mine.

Originally Posted by Jekyll and Hyde

So with respect to the oiling channels in the feed cradle, this is what should be oiling it:

IMG_20201222_000852_591x1050.jpg

The oil cup on the front of the head feeds through to the hole with the allan key sticking out of it, which is directly above the cradle. Of course, depending on the manufacturer of yours, they may have copied the casting for the cradle without understanding the reason for it, and omitted the oil cup...

Top section of mine has an oil cup and the oil discharges from that onto one of the gears

Originally Posted by Jekyll and Hyde

On the topic of grease in the back gears - mine has plenty of grease still in the teeth of the gears (never been apart in the ten years I've had it, who knows before that), so I don't think there's much wrong with the idea, providing enough grease is packed into the housing on assembly (see H&W machine repair videos on Youtube for how much they use).

I've watched a few of theirs and others. Barry states he uses grease as he doesn't know if the user will lubricate the machine properly (or something along those lines)

Originally Posted by Jekyll and Hyde

However, if you wanted to do something about it, the Supermax also has a grease zerk at the rear of the housing, which feeds directly into the back of the small back gear. Location again indicated by the allan key in the photo below.

Mine doesn't have that.

Originally Posted by Jekyll and Hyde

IMG_20201222_001108_591x1050.jpg

I wouldn't personally fill it with oil - mine had a fair bit of oil built up inside the housing, and it was weeping down between the red cast section and the outer section, and drooling down the outside of the head from the seam between the parts all the way round. So if you go that way, I think you'd want to seal between those two castings with RTV silicone or similar.... Will still leak down between the large bull gear 'carrier' and the housing though over time, eventually giving you some extra spindle bearing oil I guess...

I wouldn't fill it with oil as it will eventually end up on the table. I think the original idea was to use oil only and for the oil to trickle down through the bearings and eventually dripping out the bottom of the spindle. (as Cask warrior mentions in his post) However I agree with what you said that the manufacturer of this copy didn't really understand how it was supposed to be. I could chuck it back together as it is and just use grease and it will probably out live me, but then at some point a subsequent owner will have to go through what I am atm.

Originally Posted by Jekyll and Hyde

Mine's rather unlikely to go back together in the next few days since I'm having too much fun with the Graziano, so if you want any photos of some other part of the head let me know.

Thanks will keep that in mind. Peter

Originally Posted by caskwarrior

The original bp design is that oil trickles down to the spindle bearings and out. So unless you replace with sealed bearings make sure that can still happen.

Sent from my SM-G973F using Tapatalk

Absolutely. peter

I've managed to find a decent exploded view of a series 1 BP J head.

https://www.hardinge.com/wp-content/uploads/KneeMill-Parts-Older.pdf

The bearings that support the bull gear (page 4-7, items 71) are clearly shown as being open without seals or shields. That would make sense so that the oil can trickle down through the bearings and eventually down to the spindle bearings.
My gut feeling is no grease in the gearbox. Why would BP put an oil cup in,(page 4-7, item 55) that discharges directly onto the teeth of the gear if the gearbox was meant to run grease? (During my time as a fitter in the power station, I never saw a high speed gearbox filled with grease. Always oil.)

This still doesn't allow oil to get to the top of the worm gear cradle though. Got to think a bit more on this one.

peter

Had to go have a look at pictures of step pulley heads after reading through this. Looks like the step pulleys had two versions, neither of which had the front oil cup for the quill feed like mine.

The part that was really confusing me was you guys talking about oiling the spindle bearings - mine has an oil cup in the right hand side just below the casting I pictured earlier, which feeds via a pipe and wick onto a felt filter - this is directly in the top of the quill, and is only for the spindle bearings.

Looks like from photos on the net that only some step heads have this oil cup though, earlier ones seem to use the one oil cup up high to feed everything (probably including the bull gear teeth) so now I'm following.... *edit* Now I see the oil cup, bollie7 posted as I was writing.

If you did use grease, my suggestion was that you could drill and tap the housing to add a grease zerk like my Supermax in order to be able to add grease later - but being a step head, the casting might be a bit different anyway I guess.

My concern with adding a grease fitting is, where does all the grease go? Eventually the housing will fill up and potentially over fill the bearings (if they are open)

in relation to "mine has an oil cup in the right hand side just below the casting I pictured earlier, which feeds via a pipe and wick onto a felt filter - this is directly in the top of the quill, and is only for the spindle bearings."

Mine has an oil cup there as well, however the copper pipe inside isn't long enough to reach over to the top of the spindle. I suspect that is another manufacture assembly mistake as well.
Years ago when I had the table off it the first time, I found that one of the front X axis one shot oil pipes ended in the middle of the way but missed the oil way itself by about 20 mm. So for 20 odd years of life in a commercial machine shop, it had been running with oil only lubricating one part of the X axis way. I fixed it by just extending the oil way over to the oil pipe by using a round carbide burr. 5 minute job but too hard for the factory.
peter

I rebuilt my Bridgeport step-pulley J-head prior to installing it on my Victoria mill (the Frankenmill). I puzzled over the lubrication system too. It is carefully arranged so that the oil you put in at the top lubricates the drive housing bearings, the bull gear, the worm drive and then runs down into the auto feed gears before finally ending up spraying in your face at the bottom of the quill when you start the machine after a few days. I can't recall exactly where that oil pan in the casting of the worm housing gets it's oil from but I do recall there was an 'ahah!' moment when I figured it out. Might be that it is right under the perimeter of the bull gear and gets oil spilling over the edge of the gear? That seems to ring a distant memory bell. You definitely don't want sealed bearings in the head unit as they will prevent oil making it's way down to everything below. I very nearly made that error. I have read articles where people talk about 'filling' the top with oil as an 'oil bath' for the bull gear; if they are doing that then they must have sealed bearings on the bull gear and the feed drive system has to make other arrangements. The Bridgeport system is a 'total loss' lubrication system. Like a Pommy car.

Old car steering boxes were typically filled with thick oil. When the steering box seals wore and the oil leaked on the garage floor owners would solve the problem by filling the steering box with grease. This solved the leak problem, but after the gears wore a track in the grease (30 minutes driving) the gears were no longer lubricated and wore quickly.

Penrite and others sell 'semi fluid grease' or 'steering box grease' that addresses the leak and no lube problems.
SEMI FLUID GREASE | Penrite Oil

Well I've had an interesting afternoon. I got stuck in, made and fitted an oiler to oil the top of the cradle which worked really well. The pipe cleaner wick worked better than I expected.

oiler 001.jpg

So then I made and fitted another oiler to oil the bevel gears for the feed drive. All good, feeling very pleased with myself. (forgot to take a picture)
Then I put the bull gear housing back on to check something and discovered that the alignment spigot on the bottom fouled the oil line. oops.
I looked at trying to relocate the oil line a bit, even went so far as to squash it a bit but just couldn't quite get the clearance. (I only had some old 1/4" copper pipe. 3/16" would have been better.

So then I did what I should have done to start with. I pulled the bull gear and bearings out of the housing and put the housing back on top. (with oil pipe removed)

As it turned out the original Bridgeport designers did think about oiling the cradle. Its quite clever actually.

When the cradle is in the engaged position, the oil way protrudes into the space below the bearing. Not by much, only about 2mm, but enough that, if the machine is running open bearings as originally intended, any of the oil working its way down from the top, dropping off that side of the bearing would drop onto the oil way.

cradle 001.jpg



The outer race of the bearing is about 6mm thick and the oilway protrudes by about 8mm. So my oiler was a wasted exercise. Doesn't matter I'll just stick a plug in the hole I drilled and tapped.

I'll keep the other one I fitted though, as it will help with the feed gearbox.
Obviously the manufacturers of my clone didn't really understand how the lube system works. Other wise they wouldn't have specified shielded, grease packed bearings under the bull gear. My bearings feel fine so I will be removing the shields and grease before reassembly.

Another thing I discovered is the alignment spigot on the bottom of the bull gear housing is 0.9mm smaller than the hole in the housing below, so can move around all over the place during assembly. That might explain why the dogs on the splined gear hub are showing signs of wear.
I might see if I can shim the spigot on reassembly to improve the alignment.
to be continued......

Merry Xmas everyone
Peter

I was pretty tired yesterday and I missed something that is blindingly obvious when looked at when not as tired. DUH.
I was thinking about this last night and realised that my idea of how the lubrication works is also possibly incorrect.
What I said about the oil getting through the bearing is a good idea except its flawed. In this case because of the spigot in the case for the bull gear bearings.

bull ger case.jpg

On another look with a slightly clearer head, I realised that the oil that has come down from above onto the teeth of the bull gear cant get into the bull gear bearings unless the bottom of the case had enough oil in it to raise the oil level to the top of the bearing housing spigot. I haven't measured the height of the spigot yet but it looks like its around 8mm high. That's a fair bit of oil. This amount of oil would also mean the selector shaft to engage the small gear with the bull gear would be below the oil level. This in turn would mean that the oil would be constantly leaking out around the selector shaft.
Maybe this is what is meant to happen.

Hmm back to the oiler I think.

peter

If I recall correctly H&W Machine Repairs do away with the oil filled scenario when rebuilding, and replace with sealed bearings.

watch to around 2:38 https://www.youtube.com/watch?v=IwroB3CuYoY&t=20s

My BM30 uses sealed..lot later model of course. The box has a grease nipple. The top of the box has a slot in it to allow excess grease to escape.

I'm still not keen to just use grease in the gearbox. Mine had quiet a lot in there yet the gear teeth were dry and shiny. When I was on the tools I never saw a gearbox with grease in it. Always oil.
Actually in this video at 10.26 hes says he likes to use grease because "too many people just don't oil their machines like they should" which to me means its a backside covering exercise for the machine rebuilder so no one can come back and accuse them of being responsible for a machine that has failed due to incorrect oiling by the operator. (cant blame the rebuilder for that either).
I remembered the other day that I have a can with some really runny grease (or thick oil) that I've had for years. It was left over from an overhead crane gearbox repair job. So (if I can find it) I will look at using some of that. What ever gets flung against the sides will make its way back to the lowest point in the gearbox, covering the small gear when its disengaged and being brought up to the bull gear when the small gear is engaged.
All good fun.
peter