Looking at an m-head tonight - what to look for

[SteveM]

I'm looking at an older round-ram M-head tonight (the story behind this to come later).

Table has some surface rust. It's been sitting in a garage.

Not sure if it's MT2 or B&S7, but we will find out tonight. Comes with a set of collets. Missing the fine feed handle.

Table works smooth back and forth.

Will power it up when we get there.

I should bring my fine feed handle and a squirt can of oil to fill the reservoir before we fire it up.

What else should I bring?

What tests should I do beyond running all axes to their extreme ends and trying the head in all speeds?

Steve

[NP5002]

I would take a mirror with you to look up in the collet to see if the pin is still in place and for ware.

Dave

[John Evans]

I would take a mirror with you to look up in the collet to see if the pin is still in place and for ware.

Dave

Neither of those collets types on a M head had the pin, R-8 only which a M head never was.

[SteveM]

Well, the table is square to the column.

Everything moves thru the full range of motion.

The knee is hard to move up and down, but it feels like congealed grease is the culprit. The handle for the knee lock is broken, but that will be an easy fix.

It's missing the handle on the turret to crank the ram. Easy enough to find or make.

The motor is original and it's pretty noisy. It was hard to hear how much noise was from the spindle, but it didn't seem like a lot.

Bad part is that the threads at the top of the spindle are gone. I suppose they could be re-threaded smaller and a new nut made. A helicoil would be good, but it's probably an odd thread and left handed to boot. Maybe turn it down, shrink fit and pin a sleeve on it and put new threads on.

It's a B&S7, not MT2, but it comes with almost all the collets.

Lots of grease and grime on it and the surface rust means a lot of elbow grease.

We are working on how we are going to remove and transport it.

Here's the kicker - this is for a 16-year-old kid. He's a student at the local vo-tech school in the machinist program.

Can you imagine the faces on his classmates when he tells them he has a Bridgeport?

Steve

[spro]

This is great. It just is.

[spro]

The thread atop the spindle is to act as a press type thing to force the tapered colletbar out. We know about these AC bearings and don't want to put a hammer on the draw. There could be another unit attached to the messed up threads which acts the same way. We can't weld and make the shaft wider for it wouldn't pass the bearings' i.d. for you or another to replace the bearings.. So Helicoil would require some re profile of the old thread for it to seat right. I mean there is no reason to do it unless it contains the ability to eject the collet. The O.D. of the coil would be larger? maybe than the O.D. Then it gets back to another thing which is removable.
I watch some M heads across the net and many have lost those threads so you are not the lone ranger with this. This will be an interesting discussion. There is a solution outside and the rebuilding or remaking that drawbar collar to match. Sounds like work to me and there is something different.

[David Merrill]

Seems to be lots of online manuals and other info available for M-heads:

https://www.google.com/webhp?complete=0 ... %22+manual

David Merrill

[WJH]

He is probably going to be as excited as I was when I got my knee mill

[SteveM]

He is probably going to be as excited as I was when I got my knee mill

He already is. He came down with us to inspect it.

The nice thing going forward is that you can always find something to get him for Christmas or his birthday.

Vice, edge finders, hold-down clamps, etc....

Steve

[WJH]

Lucky kid!

[David Merrill]

Happened to run across this tonight: http://bridgeport.askmisterscience.com/drawbar.htm

David Merrill

[Rex]

One workaround: Get an ER32 collet chuck with 7B&S arbor. With that you can fashion a simple non-ejecting drawbar and leave it in place. I bought one for mine off ebay for about $50