View Full Version : Bridgeport lubrication
08-08-2007, 07:41 PM
I've done a search for past threads on this issue and read a lot of them but I'm still a little confused. I have a 1988 model I Bridgeport with a 2 hp variable speed head. It calls for light spindle oil in the side cup, heavy medium oil in the front cup and lubriplate 107 in the side set screw hole. I just bought some Tru-Edge light duty spindle oil from Enco but found it to be ISO 22 when I read the label. What's the consensus on the correct ISO numbered oil to use as light spindle oil? Same question for heavy medium? Is there a good source for the 1.75 oz tubes of B-105 lubriplate that is the suggested replacement for lubriplate #107?
I know you've probably hashed this over many times but if someone would help me to identify the correct lubes for my Bridgeport I'd be very grateful.
Thanks, Mike Hannah
08-08-2007, 08:02 PM
I got a tube of the Lubriplate 105 at Carquest auto off the shelf. The instructions don't tell you, but look inside the hole and (don't recall engage or disengage, you'll have to look) so that you see the big bull gear turning. Put a few CCs of LP into a syringe with the needle removed (I use a Horse Syringe with plastic cone installed sans needle). With the machine running, squirt a few CCs of LP in there onto the bull gear. Replace plug.
I'm using essentially the same Light Spindle oil for my spindle with general use. If your running really high rpms most of the time, they recomend a lighter oil (don't remember where I read that).
For the heavy/medium, I use Mobile ISO 68 DTE R&O. This is just for the power spindle feed drive, so not that critical anyway...
08-09-2007, 03:18 PM
I bought a 10 oz. tube of "Lubriplate NO. 105 Motor Assembly Grease" today. I hope that this is the same as the B-105 grease that Lubriplate reccomends for Bridgeports. Would a fairly heavy hydraulic oil (a little heavier than 30 wt. motor oil) work for the heavy/ medium oil Bridgeport specs for the power spindle feed drive cup? I have several gallons of this oil but don't know the specs on it other than it was used as a gearbox lube where I work.
08-09-2007, 03:50 PM
I don't know how well it would match either. There is no way I would put it in the spindle. But for the power feed... maybe... However, the ISO 68 is such a wide range multi-application oil, it's good to have on hand. My last 2 lathes have used it at many of the lube points, it is R&OI, so I use it for oiling everything while reassembling after cleaning (Brake Cleaner and Zep Purple leave things susceptible to flash rust).
I would recommend you join the Yahoo Bridgeport Group (http://groups.yahoo.com/group/bridgeport_mill/). These forums are great for general machining info, and you can get some great specific info, but it's hard to beat the very focused groups for questions like this. There is also a (sorta) Bridgeport focused forum on PM where I've gotten some great info too.
08-09-2007, 04:22 PM
I called the Lubriplate folks quite some time back for clarification. As soon as I mentioned 107, the guy said "you must have a Bridgeport mill". Turns out the 107 was a misprint on the lubrication plate on Bridgeport mills as #107 never existed.
105 is sold as motor assembly lube. You can just squirt it in through the hole with the big tube. The "shnoz" on the tube will seal against the hole. It lets you apply a bit of pressure that way to force it around works that you are lubricating.
By the way, its only the bull gear engagement mechanism you are lubing thrugh the grease hole on the side. The bull gear is unreachable except for some older models that acutally had a grease zerk at the back of the bull gear housing. I don't know why they quit that, but when I restored mine, I made use of the flat that was cast in that location to drill and tap for a grease zerk. This gets an NLGI 1 EP grease. I use an Exxon (edit) product I bought from H&W Machinery repair at http://www.machinerypartsdepot.com
The standard intent is that the bull gear housing is packed "full", but I found in mine that its a scheme that doesn't work well. After enough rotation, it flings all grease away from the bull gear and you may have no way to regrease short of complete disassembly. The bull gear will produce a slight ring while its engaged and the mill is running as its the two metal gears with no lube to damp their contact. With the zerk in place, you can shoot a glob of grease right on the idler that runs in contact with the bull gear when it is in play.
As for spindle oil, find out if your spindle bearings have been replaced with sealed bearings as is the case in a lot of mills. If so, running thin oil in on top of the bearings may only serve to wash out the grease contained inside the seals.
08-09-2007, 04:34 PM
That's interesting, hadn't heard that about the spindle bearings (at least not that I recall). My head was rebuilt at a Bpt/Hardinge reman facility less than a year before I bought it. But I was not told anything about changing the maintenance lubes. I do recall him saying it now had "sealed bearings". Hmmm... I would be scared to eliminate the oil without being absolutely sure, then again, it could be too late if this is the case?
08-09-2007, 04:36 PM
Here's a pic of the back gear housing as I was putting my head back together. X marks the spot where the grease zerk is (on the outside of the housing). You will note that I did go ahead and pack the idler gear area with grease but left the main area around the bull gear dry. This is so that a squirt or two of grease on the fitting will immediately apply grease to the idler gear and there is no room for it to sling off the idler.
You can pack the whole thing with grease as is the case with the later mills, but it looks like it would take close to three tubes of grease and only a tiny bit ever does anything. As stated before, its nearly impossible to pack it tight enough to ensure that it will never fling all the lubricant away from the teeth. My housing was full of grease when I disassembled it, but the gear teeth were completely dry.
I wish I had taken more pictures during re-assembly. I could not find one that shows the stuff that gets lubricated with the Lubriplate 105. Its the works that drive the bull gear up and down when you rotate the lever on the right side of the head to engage back gear.
08-09-2007, 05:02 PM
I forgot to mention this in the previous post. Mine had had its spindle bearings replaced with sealed bearings, so what I did was to sort of "correct" where the tube and pipe cleaner pointed that used to drip oil on the felt ring that protects the open spindle bearings. Oil used to drip on this ring and then flow downward to the bearings. I bent the tube a bit, trimmed its length (its soft aluminum, and pointed the replacement pipe cleaner that runs down the middle to drip oil right at the outside of the quill. This means that the quill still gets lubed in its bore, but the spindle bearings down the middle should not get much if any oil.
Its not something you can do short of quite a bit of disassembly, but it renders the cup still useful and insures that the quill still gets oil way up top where its hard to reach.
An alternative if you want to still oil the top of the quill but not the bearings is to run the quill down, and reach behind the down feed stop nut threaded shaft (don't reacall the correct term) and slide the sliding sleeve up a bit and reach in and squirt oil on the top edge of the quill that is then visible.
08-09-2007, 07:53 PM
Thanks pcarpenter, you've given me a better idea of what I'm lubricating and a better knowledge of the inside works of the head. I'll go ahead with your idea of sticking the schnoz of the large tube in the hole to lube the engagement mechanism. I appreciate the reply.
Thanks, Mike Hannah
08-09-2007, 07:59 PM
I appreciate the info BadDog. I will check out the Bridgeport group on Yahoo- I didn't realize there was one. As far as the ISO 68 oil goes I guess I'll just get a gallon of it if I can find it locally-otherwise I'll have to pay about 10 bucks for shipping from Enco. Too bad I didn't know about it a couple of weeks ago when I ordered some stuff from Enco.
Thanks again, Mike Hannah