Bridgeport M head - disassembling help needed.

[Gennady]

Hello team.
I am working on my newly acquired round ram BP mill with M head head. I removed pretty much everything and now trying to push quill out , but it stuck there. I was trying to heat housing and move quill but, so far, no luck.
There is still pinion that need to be pulled sideways...
I am wondering if there any set screw or detent that might be still there and hidden under paint?
Thanks.

 

[Susquatch]

Give this website a good look.

They have many references that could help you zero on on the answer to your questions.

Home

Your trusted source for Bridgeport Machine Replacement Parts and Services. We're the best place to get metalworking parts & services online!

machinerypartsdepot.com

If you can't find the info there, give them a call. Thyey are very helpful.

I think this is the video you need. I may be wrong, but I think the quill assembly is the same for the pulley drive and the Varidrive.

Step Pulley Head Rebuild Videos

machinerypartsdepot.com

 

[Gennady]

OK. I decided to continue on this thread with my efforts of rebuilding M head.
I decided to build quick and dirty hydraulic press out of shop made engine crane. It is super heavy and super duty shop made crane that I salvaged from junk yard several years ago. It is built with front crossbar, which makes it quite fiddly to use, but makes it good press . I put it vertically and used car bottle jack with help of random parts scattered around.
After few mnutes of balancing this contraption I have quill out in 30 seconds - right tool for the job makes all the difference.

 

[Gennady]

Going forward with spindle disassembling.
It is quite a lot of rust in there. Probably rain was trickling down freely instead of oil .

I noticed that ball bearings were working not in the conditions that manual suggests. First- bottom two are 6205 instead of 7205. Top and bottom pair is sealed, though it has to be regular (unsealed) for "lost oiling" lubrication system. Second - there were no any spacers between pairs -ball bearings were set back to back with one common spacer between top and bottom pairs inner races.

Wondering is that known alternative way to install ball bearing this way or just a "don't care" way?

 

[Susquatch]

Top and bottom pair is sealed, though it has to be regular (unsealed) for "lost oiling" lubrication system.

Without the details for your particular mill, I cannot say. What I can say is that there are different opinions out there about spindle gearing lubrication. The well respected folks at H&W machinery who rebuild a lot of machines recommend replacing the lost oil system in Bridgeports with grease. I've never debated it with them, but I think it has more to do with oiling habits than science. I went with lost oil cuz I oil religiously.

At some point, you have to listen to all the advice and then make your own decision. I'll take science over popular advice and opinions any day. But I can't find any.

 

[Gennady]

Thanks Susquatch. Appreciate your input. What is your opinion with regard to spacers vs. no-spacers bearings arrangement?

 

[Susquatch]

Thanks Susquatch. Appreciate your input. What is your opinion with regard to spacers vs. no-spacers bearings arrangement?

I don't really have an opinion cuz I'm not familiar with your machine.

Edit - that wasn't fair. Generally speaking, I prefer a spacer or bushing between bearings.

 

[Bandit]

As I am also not familiar with your machine, I would suggest to follow what the manufacturer's recommends at least as a base point/start point as to lubing and the assembly. Sometimes that leads to the fact that the recommended product or part is not to be found. Oil comes in a "very large spectrum of types", the same to be said for grease, and sometimes parts, and paper works.
There are crossovers covering many different oils and greases, however not all, sometimes you can not even get the product in Canada, ( not going into that!,,#£¥).
As to bearing placement/assembly in a piece of a equipment, understanding what is happening is important and "not alway" apparent. Is the bearing allowing the shaft to turn while being supported and kept in position and or alinement, is the bearing preloaded on the shaft or in the housing? Does the bearing have both races the same width?( many are the same width, but some are not). Spacers used to take up space and or to preload, or to allow preloading with a threaded cap/nut in many cases.
As to the bearings, 7205 replaced by 6205 sealed, they are very different, the 6205 is a "plain" ball bearing, the 7205 is an angular contact bearing. It seems the 7205 bearings may have been replaced with the 6205 bearings possibly due to price/availability, very/most likely after production. They are not up to the same work loads or thrust loads as the 7205 bearing. I would replace them back to the 7205 bearing, in doing so some other parts, shims, spacers may need to be replaced that seem to be missing, all while trying to see if anything may have been "modified ", I am not not trying to put you off on this, just saying.
Remember, it is a BridgePort head, many have walked this road ahead of you, the people that rebuild these for a living know more about these then I do, and they likely warranty their work.
And as usual this is my views, thoughts and may not be the same as others.

 

[Gennady]

I would replace them back to the 7205 bearing

Thanks. This is what I am planning to do. I already ordered matched pair of 7205 to put as bottom BB in the spindle. I will arrange spacers same way they were before (even if this is not an original way). Second pair will be 6205 - regular pair. All four are without sealing, so I will "restore" original oiling system. I will try to check wobbling, FWIW, after spindle reassembly.

 

[Bandit]

Keep in mind, with angular bearings, in your case the 7205 bearings, that they should be assembled the right way. Back to back or front to front increases load carrying ability axially in both directions, while front to back,or back to front only increases axial loading in one direction.
You may need to check what original setup was, there may not be shims between the bearings. The spacer(s) may/could be shimmed.
You will also need to clean, remove rust etc., very well to stop "stuff" getting into the now unsealed bearings. Remember to lube bearings as assembling as lubing later may take some time to work into, through bearings, also a bit of lube on any seal lips. Though you maybe familiar with such, just putting it out there.
I am not an expert, still learning " most/some"days, a bearing catalog and manufactures assembly info. helps.