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What's new

M Head Repair

I think I still have the one I made to do the
job. I'll check when I get home tonight, but
I'll be working pretty late. I'll post up if
I can find it, by midnight tonight.

Thanks for checking. I look forward to a positive result!
I tried to make one this morning, but all I did was demonstrate my lack of welding experience. A 1 1/4 iron pipe with 4 pcs of 1/8 x 3/16 key stock was a perfect fit, but I could not weld it well enough to keep from breaking the welds inside the pipe.
Another idea I'll try, if needed, is a custom 'wrench'. Long flat stock (with a hole for the shaft) and 4 holes with 3/16 sq tool steel pounded in to line up with the notches. Sounds like it would work...
Also considered buying a fixed size spanner and cutting it down to fit into the quill recess, then welding it to flat stock. I can do simple welds! The mill came home (45mi) on a trailer with welded spring supports that I did. None broke yet...

Ah, in a fit of fantatical organization, I stuck
all that M head stuff in a box in one spot. So
I've got the 'wrench' I made, which is a round
chunk-O-steel with a hole that looks supiciously
about the size of an M head spindle. It's
got four teeth on the bottom which I guess
engages the slots on the nut in question.
Two flats to drive the thing.

Where in NJ are you? I do on occasion get down
to the bergen county area.

Good news!
I'm in the other Jersey, South Jersey.
USPS or UPS could work. I have a UPS account that you could send it on, or I can send you the money for USPS. Send me a PM with your choice/details.

Shoot me your address to

jrr0 (at) us (dot) ibm (dot) com

where that's a zero in the address, not an
"oh" and I can get it out to you possibly
today if the snow lets me get out to the
post office. Otherwise it might not get
in the mail till monday.

John E I'm in the proccess of disassembling my m-head and i noticed that although the oil level is higher than the bearings themselves it does have to travel upward approximately 2-21/2" inside the housing i had the same problem visualizing the oil flow myself. after 1/2 hr flippin and turning the housing and doing a little measuring it is easy to see so you were not to far off the mark. al
It must "M" head month. I too have just bought an m head to put on my Clausing mill and could really use a decent set of illustrations. I was able to find one on the yahoo group but it is very small to make out anything. My email is hfgi "at" shaw "dot" ca Thanks for the help.
Download file is back

My website logs indicate that people are still looking for the bridgeport zip file, but it seems to have been removed.
I have loaded it back to the server, so the link is good again. Beware it's 60mb, and contains the fillowing files:

Round_Ram_Manual 20-30.pdf
Round_Ram_Manual 31-38.pdf
Round_Ram_Manual 11-20.pdf
Round_Ram_Manual 6-10.pdf

Some years ago,lubrication of the M head was discussed on this forum. A Bridgeport tech actually called me,and told me to remove the screw from the lube hole on top of the housing,screw in a tube of lithium grease,and squeeze in a teaspoon of grease.

Please correct me if I'm remembering this wrong. I have a high speed M head that I haven't yet put to use,and don't want to lube wrong.
Looks like the files have disappeared agin. Would you be able to post a new link?


John E,
Thanks for posting this nice collection of files:D

Just downloaded and worked fine. Browser opens a new "Tab" page that is blank and that signifies that the files are downloaded.
Check to see where downloaded files are sent/saved.
BP files from John E.jpg
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I think I got my M-head manual from Ozark. We have several manuals for the J-head and newer BP's, which I think do well enough explaining basic construction, maintenance, and operation. Having some diagrams of the what's different with the M-head/round ram helps though.

Concerning the spindle bearings and their lubrication: on mine I believe the pulley bearings are sealed while the rest are all open face, so by my understanding the oil doesn't need to go up from the oil cup, just down. The spindle bearings of course need a pre-load and dictate the amount of precision in the head, but the pulley bearings don't see any axial load and don't require the same level of precision so sealed bearings should work fine.

When I started working on my 1941 M-head BP (came with our 2006 shop merger), I put a tool in the spindle and started cutting and noticed the finish was terrible and my cutter kept slipping down, then I realized the tool was fine, the spindle was falling out of the machine! I opened it up to find that the take-up nut on top of the bearings had come loose and messed up the threads. Luckily I had a Timken tapered nut on hand that matched the original perfectly (stock from another application) and I was able to chuck the spindle up and single point the thread back to usable shape. I wasn't sure how long it had been run with the loose nut but I took a gamble and put it back together with the existing bearings and made sure that the nut was secured with the sheet-metal locking tabs, and it's been working fine for a 5-6 years now. Finish is fine and no noticeable run-out. Granted I'm not jig-boring with it, but it works fine for 1/2HP .005-.001 tolerance work.
The oil from the wick feed cup on those M heads *must* go through the pulley bearings before it
goes through the upper spindle pair before it gets to the lower, angular contact pair. If one puts
sealed bearings in the pulley then NO OIL will get to the lower bearings.