PDA

View Full Version : Bridgeport J head bearings and lubrication



lakeside53
01-05-2008, 01:16 AM
Ok.. Long post. Bear with me… I have read every post about bearings (those that came up in searches!) on this site, Yahoo groups, PM etc, and still have questions on bearing replacement in the J head, and the lubrication system.

I’ve taken apart my step pulley J-head (1967) to the bare iron, cleaned and inspected everything and now I’m ready to reassemble it, replacing several parts with used, and some new bearings. It had numerous small issues, but has basically been neglected, robbed for parts and partially disassembled by “somebody without a clue”.

I need to replace my pulley, lower bull gear housing, and top spindle bearings. My lower spindle bearings, after cleaning, seem “o.k”. I looked up the prices with the usual suspects, and came up with big swings in prices.

For the 5 bearings, my total from ICIA – $340.20; H&W - $64.75; Alternate - $437.40…. wow… not so much the prices, but the differences. So I dug a little deeper.


Pulley bearings:
My 1968 manual says “one pair 207”.
Later parts lists say 207KDD DB732
Mine are MRC207SFF DB. The “DB” is engraved by hand. I’m 100% sure they were assembled (no idea by who) in reverse – face to face, instead of back to back.

ICIA - $18.90 each
H&W - $11.96 each
Alternate - $24.30 each

Question: None of these prices seem to reflect “DB”. Do these bearings need to be “DB”?

Bull gear bearings:
1968 - “I pair 208”
Later - M208K DB J732
Mine - Fafnir M208K C2 - no sign of “DB” or side markings

Question – what is the significance of the single “M” in the Fafnir bearing number? I know “MM” denotes precision.

ICIA – $56.70 each
H&W - $16.16 each
Alternate - $72.90 each

I’d like to think ICIA and Alternate are supplying “DB”, but…


Top spindle bearing:
1968 – FAFNIR M206K spec E6578
Later - M206K 123J30
Mine – 6206 C2.

ICIA – $94.50
H&W – $8.51
Alternate - $121.50

Again, it “seems” (from the price) ICIA and Alternate are supplying higher precision bearings. However, I read both on this forum and other places that a precision bearing is not required in this location…

I’m guessing my bearings are the originals. They suffered from both too little oil at times and the “dumb” dirty lubrication system. Any junk that gets into the pulley area can get into the reverse gear housing. Once there, it’s a short trip THROUGH the lower bull gear bearings to the quill and spindle “filter” – the felt pad. How good a filter is this pad? Then give it a few years or decades. In my case the felt had at some point partially dried out and distorted. Plenty of pulverized chip material was evident. Some chip and dirt material made it to the top spindle bearing, and some likely down to the main spindle bearings. The killer for the top spindle bearing was water in the felt that made a spot of rust.

I see that H&W supplies a SHIELDED (not sealed) top spindle bearing. You’re then supposed to grease the lower spindle bearings. IMO.. over time the oil that required for the bull gear bearings is going to pool up on the bearing shield and wash out the grease. The lack of oil flowing though the spindle bearings is going to allow dirt to get back though the nose drain holes and labyrinth seal grooves. Even if SEALED ABEC7 spindle bearing are deployed, oil is going to fill up the quill above the bearings. Am I missing something?


So… WHAT if I put two sealed bearings in the bull gear housings and fill it with grease etc like the Series 1? At least the junk from above won’t be washed into my quill/spindle bearings. Then either, continue to use the existing loss system with open sprindle bearings, or, seal all spindle bearings and redirect the wick to just oil the quill area.

Any experiences with the above suppliers bearings?


Comments?


Andy


p.s. Apologies to members of the Yahoo bridgeport group - I posted there also but the post is hung up waiting for approval.

doctor demo
01-05-2008, 01:31 AM
Andy, try CNCzone. COM I seem to recall several in depth thd.s on bp spindle bearing replacement and precision bearing markings and descriptions of the various markings.
Steve

ckelloug
01-05-2008, 03:37 AM
I just got a quote from wells index to rebuild my Bridgeport J head. They said $475 to replace the spindle bearings and touch up the R8 taper.

BobWarfield
01-05-2008, 09:20 AM
I just got a quote from wells index to rebuild my Bridgeport J head. They said $475 to replace the spindle bearings and touch up the R8 taper.

ckelloug, no sooner did I read this than I saw Lazlo's quote about Wells Index over on the "made in USA" thread:

"They also have a spindle grinding service that's surprisingly cheap (for just about any spindle, not just Wells Index machines), and if you send your spindle bearings with the spindle, they'll grind the spindle in its bearings, and guarantee a 0.0002" TIR."

If they regrind the taper and spindle to fit your bearings for $475, AND you get new bearings for the same price, I'd call that the deal of the century.

Cheers,

BW

lazlo
01-05-2008, 10:32 AM
Cameron, are you sure that quote included bearings? When I looked into the "big three" spindle grinding services, they ran around $475, but that didn't include the bearings.

The Bridgeport J-Head needs a matched set of ABEC-7 7207 angular contact bearings, which run around $200 - $300 for the set, depending on where you get them.

Andy: the 6206 radial at the back-end of the spindle, and the 5207 dual-row angular contact bearing in the pulley stack are not precision bearings, so they should run ~$20 - $40 at your local bearing supply house.

I prefer sealed bearings in the spindle (over shielded), but sealed bearings have a bit more drag from the seal than shielded, so it depends on how anal you want to be...

lakeside53
01-05-2008, 12:01 PM
Pulley stack: angular contact? are you saying I can just replace the M207 deep groove with 5207 angular contact? How would I set the preload without changing the length of the inner/outer spacers.

Sealed bearings: If you seal up the spindle bearings, do you also seal up the bull gear housing?

lazlo
01-05-2008, 12:13 PM
Sorry, I got my pulley bearings exchanged -- I have a Millrite head and a Bridgeport J-Head for my Millrite, and the Millrite uses a single 55207 dual-row angular contact bearing in the pulley stack. The Bridgeport J-Head uses a pair of 6207 radial ball bearings instead.


Sealed bearings: If you seal up the spindle bearings, do you also seal up the bull gear housing?

Precision spindle bearings are almost always open cage -- i.e., they don't come in sealed or shielded variants.

Mark Hockett
01-05-2008, 12:28 PM
lakeside53,
I just sent you a PM about some bearings

lakeside53
01-05-2008, 12:39 PM
For the pulley - if I use a non-DB set of M207 bearings, do I need to set preload with a shim?

lakeside53
01-05-2008, 12:43 PM
Precision spindle bearings are almost always open cage -- i.e., they don't come in sealed or shielded variants.


I see sealed spindle bearings adertised in the BP sizes. I read in a few other posts/sites that these are ABEC5, not ABEC7, but some contradict this. Many of the Taiwan clones appear to have sealed spindle bearings. Anyone have any illuminating information ?

lazlo
01-05-2008, 12:46 PM
I see sealed spindle bearings adertised in the BP sizes. I read in a few other posts/sites that these are ABEC5, not ABEC7, but some contradict this.

Where are you looking? Are they Chinese bearings?

I'm got a set of ABEC-7 Fafnirs and two sets of Barden 7207's (the one's that go in the Bridgeport spindle) and both are open cage.

ckelloug
01-05-2008, 04:46 PM
Price to install new bearings and touch up grind the R-8 taper on Series one type knee mill is $475.00.

You will need to send us the spindle and quill as an assembly to have it reground. Please send it in a wooden box or heavy cardboard with wood ends. Insure for $1800.00 and put your contact information on the inside and outside of the container.

You are responsible for freight charges to and from our facility in Muskegon, MI 49440

We will be closing for the holidays on December 21, 2007 and will reopen January 2, 2008.
Please contact me if you have any questions.


Thank you,
Rick Robison
Wells-Index
701 West Clay Ave.
Muskegon, MI 49440
wellsindex@aol.com
Ph 231-759-0950
Fx 231-728-7456
Wells-Index website http;//www.wellsindex.com/

WELLS-INDEX YOUR ONLY SOURCE FOR QUALITY
KNEE MILLS MADE IN THE *USA*

We also rebuild Index, Wells-Index and Bridgeport Mills

Complete rebuilding starts at $6595.00


In a message dated 12/20/2007 2:33:38 P.M. Eastern Standard Time, Cameronwrites:

Hi,

I've acquired a 20 or so year old Bridgeport and I am curious what it
would cost to have the 1J spindle rebuilt and what this service
includes. It seems to be working OK but I hear a noise from the spindle
bearing that I find a bit suspicious. I am in Huntsville, AL. I assume
that it would be least expensive to remove the head and ship it to you.

lazlo
01-05-2008, 07:49 PM
Wow Cameron, like Bob said, that's the deal of the century!
They quoted me something on the order of $400 to grind the spindle if I sent them the bearings.

Name-brand spindle bearings (Fafnir 2MM207DUL's or Barden 207HDL's) run $200 - $300 per set!

lakeside53
01-05-2008, 10:58 PM
Where are you looking? Are they Chinese bearings?

I'm got a set of ABEC-7 Fafnirs and two sets of Barden 7207's (the one's that go in the Bridgeport spindle) and both are open cage.


Here's a link to Aternative's spindle bearings - sealed. $303 per set. I don't know the manf.

http://www.alternativemachinetool.com/catalog/product_info.php?cPath=198_57_33&products_id=877&osCsid=6c40c513ca0635dc3dbdd2f571c28fb3


Here's ICAI's - also sealed - $236/set

http://www.icai-online.com/product.php?productid=16486&cat=254&page=1


Mataco: sealed - $255/set - says USA manf. and ABEC7


http://cgi.ebay.com/BRIDGEPORT-MILLING-MACHINE-SPINDLE-BEARINGS_W0QQitemZ150161334292QQihZ005QQcategoryZ2 5290QQrdZ1QQssPageNameZWD1VQQcmdZViewItem?_trksid= p1638.m118



If I can ask.. what did you pay for yours, and where did you get them?


Does anyone know if any of the bearings above are actually ABEC7?