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1947 Bridgeport M head Question

WellsMechanic

Plastic
Joined
Nov 5, 2023
Hello,
I have never joined a forum before, and am autistic, so please be kind...
I have a 1947 Bridgeport M head mill, and have some questions.
Firstly, it is missing the locking knob for the fine feed assembly, and I cannot locate a replacement. If I knew the thread pitch, I could easily make one. Anyone have this information?
Secondly, I had problems with collets getting severely jammed in the spindle. are you not supposed to use a wrench to tighten them? I ordered a MT2 set, and they are too short, and too small in diameter. The locking collar on top of the spindle is stripped. I assume this may be my jamming issue?
Lastly, I am having trouble getting oil into my table ways. The oil fittings that look like grease fittings have a spring in them that is too strong for oiling. any suggestions?
Thank you all, in advance !
 
Welcome to the forum. Not all M heads were Morse taper #2, some were Brown & Sharpe #7 and very few were B3 taper. I wonder if your machine is actually B&S 7 taper not Morse. The threads on top the spindle were for a nut to retain the draw bar in the spindle. This would allow you to not only tighten the collet but also back the draw bar off and eject collet. As far as oiling you pretty much need an oil gun in my experience, most folks convert a grease gun over. Its highly likely someone already greased the machine which makes it even more difficult to oil when the passages are packed with nasty old grease.
 

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Welcome to the forum. Not all M heads were Morse taper #2, some were Brown & Sharpe #7 and very few were B3 taper. I wonder if your machine is actually B&S 7 taper not Morse. The threads on top the spindle were for a nut to retain the draw bar in the spindle. This would allow you to not only tighten the collet but also back the draw bar off and eject collet. As far as oiling you pretty much need an oil gun in my experience, most folks convert a grease gun over. Its highly likely someone already greased the machine which makes it even more difficult to oil when the passages are packed with nasty old grease.
Thank you very much for your informative reply! I recently acquired this mill along with a rotary table and a dividing head, all for free. I replaced the original motor with a 90VDC 2HP motor, and a DC speed controller, and I added a DRO as well. Just want to clear up these small details before I begin using it for real projects.
Did you happen to know the thread pitch on the knob? its number 24 on your diagram.
I will definitely find some B&S#7 collets, and I will have to disassemble the table and remove all the grease if there is any.
I know its a small mill, but its more than I thought I would ever have!
Sorry it took so long to reply. I didn't know you need to refresh the page.
 
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Proabably not metric - try 5/16 - 26.

8 mm = 5/16
1mm pitch = 26 tpi.

Approximately.
Oh, Thanks! I don't have many exotic taps in my workshop, and my thread testers are mostly nominal sizes. 26 TPI never occurred to me! I will test that!
Thanks again!
I just made a mock knob, using a 5/16-26 tap, and it is just what the doctor ordered!! You saved my day! Thanks:)
 
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