Bridgeport head rebuild

[Rex]

Looking good!

I am about to tackle grafting a M-head to a Clausing mill.
I wonder how much of your J-head rebuild is applicable to my M-head?

[spro]

Not much. The M is more simple yet the correct tools for disassembling the quill have to be made. There is the question of bearings' grade with unsealed precision angular bearings and the angle. You can work this out and find that later M heads had sealed bearings. The people who have rebuilt piles of them are using sealed bearings, so the open bearings of the stack above, wouldn't be appropriate. The age of the head is a rough guide by the serial number. I recorded some which actually said sealed bearings on the Bridgeport data plate. When you get into it, you can add more information and tighten this up to a range unknown by me and others. It may be that some have the main oiler atop for open bearings and a "weep hole" to lubricate the quill slide, instead of oil piling on a sealed bearing. I don't know.
There are a lot of steps to get it right with the preload and equal spacers but much has been changed. It may be that ABEC3 is the replacement for what was a more precision type. There are people who know why it is or isn't, worth doing a head above original spec. There is the angle of the angular bearings at the working end. For straight milling, it could be 15-20 * and if the head is a MT#2 , it would invite drilling and a different pressure angle. The preload of the nose pairs may be different than that of the radial pairs of load above. The spindle has one preload. So it returns to thinking about it and somebody already did. I have yet to know what bearings they used and how it relates to the others.
It's not micro science these days with older heads like these but we try to get it right.
The risk is doing the job badly and reflecting upon what was a very useful machine head, precise at higher speeds.

[Rex]

This M-head is supposed to run smooth and quiet, but I haven't powered it up. Mostly I need to repair damage from shipping (motor pulley, downfeed lever broken) and probably repaint the casting. I don't expect to have to replace bearings, but I may.

[spro]

Hey Rex, tell us the serial number if you don't mind. This information is constantly being narrowed down to the years they were produced and when they went to sealed bearings. I've learned a lot by reading older posts. Even the dataplate of your motor is of interest. Fairbanks Morse, General Electric, U.S. Motors ...Westinghouse.. I found, without a dataplate, there are many possibilities. Some like the shaper/slotter head are two speed motors and not reversing. The little brass "bracelets" on crusty wiring tell if you know what it is.
Anyway, I hope your bearings are fine and your pulley can be repaired. Downfeed lever; I would say it's better it broke than something else bent but can't really say that. Shouldn't of happened.

[Rex]

I'll get the motor plate data later today. I don't recall seeing any "bracelets". Is that like brass ferrules crimped onto the wire?
Where is the serial number?

The downfeed lever - is that unique to the M-head, or a common design used on other heads?
Any idea where to get one?

[Rockabye74]

I realize that I have not posted in a while. A lot has been going on in my life, but I finally put the last touches on my rebuild today. For those of you that were following a few posts back, my mill had been sitting in a shelter "in the rain" without my knowledge and had gotten rather rusty. I am happy to say that after a years worth of hard work, and a LOT of scraping, that she is back up and running and better than before.

I will admit that the scraping was long and painful, but well worth it in the end. I purchased a lot of measuring instruments that I did not own before and had to be creative in their use to ensure that the mill was aligned in all directions after the scraping process.

All in all, we had to remove about .017 from the table surface to eliminate the surface pitting due to the rust.

I am waiting for 2 more fittings to arrive for the auto-lube system, and I have a friend that does fabrication that is making me a pan for under the table so that I can capture the coolant without creating a mess. The mill will not be resting on the 4x6's for long, they are just there so that I can move the mill with a pallet jack while I work on it. I will ultimately make a steel frame with adjustable feet that are made from hockey pucks. This frame will still allow me to lift and move the mill with a pallet jack.