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flood damaged M head

Bret Rochotte

Cast Iron
Mar 8, 2008
New Bremen, Ohio
I was flooded this past Monday and have been scrambling to save what I can. I had a bunch of stuff on the floor in an out building that had about 2 feet of muddy water. The mighty M head was one such thing. I took the motor to a motor shop today, and sprayed the head with Kroil. The spindle is getting a bit gritty and slightly difficult to turn. I know it will need new bearings. What is the wisdom of trying to save this? It has a single phase motor which I think would be appealing to the home shop guys like me. I have an extra Burke milling machine I was intending to mount the head on. Is it going to be too expensive to be practical to fix? I need some wisdom, I can't keep everything.

The head is simple. I would pull the quill, dump in a pail of oil, until you can do more to it. The belt housing comes off quick, you can fit then quill housing assy in a 5 gallon bucket of oil or diesel to preserve it .. The belt housing can fit in another bucket (pulley bearings submerged)

A three phase motor and a VFD make the M head really nice to use.

You can run it the pulley groove up from bottom tiny motor pulley groove.

The belt does not have to go around the tiniest groove so you can transmit more power.

The VFD lets you have a lot wider speed range... from around 65 rpm to ~5,000 rpm or so (Spindle whip is a problem much above that.)

Instant (or with VFD, almost instant) reverse is something a single phase just cannot do...
dump diesel over the top of it turn it by hand a little then roll the head over so motor is upside down the with a pump spayer cover it good with diesal fuel add 1 gt of oil to 5 gal . to help it . then leave it dry like this every week spray and turn it a little . it will be ok . my mill went 8 ft under .. jim
Split the upper housing from the lower body and wash everything with WD-40, after all it was designed to displace water. I've actually seen steel flash rust underneath a coating of PB Blaster where water was trapped. The M Head is way simple to tear down, and pretty easy rebuild for someone with an understanding of its assembly.

Thanks for the replies, we're getting things under control, but a lot of damage to the (finished) basement and corn fodder from the adjacent field in our back yard. I tried to get the upper housing off but it wouldn't budge. I loosened the lock screw and tried to wiggle it. I have a parts book some where but I have no idea where it is right now. Should the housing come off with just that 1 screw? Thanks,

The aluminum housings can be tight on these.

1) try a bit of heat. Heat lamp, hot air gun. The aluminum has a larger
thermal expansion than the cast iron.

2) Once warmed up a bit, remove the pinch bolt from the split in the
front of the housing. Insert it from the other side, into the tapped
hole first. Put a thin piece of stock in the split for the point of the
bolt to bear on. I used a washer that just fit in there but a strip
of steel would work as well. Then *gently* snug the bolt and it
will spread the split. Crank hard and you can crack the aluminum housing
so go easy.
top spindle nut removal


I've had a little time to work on this M head, tried to make a socket from a pipe coupling by filing notches to remove this nut:


It did not work very well, need to make something better. Any suggestions? I bought a pin spanner, that didn't work, tried tapping with a chisel in one of the notches, that didn't work and seems like the wrong way to do it. Anybody make a special purpose tool they don't need any more? The bearings are bad and need replaced.

If the bearings go round at all, you could use mill to cut some slots in a piece of pipe for a socket, weld on extension to clear spindle... If bearings move even a little, just keep oiling and rocking until free.. Flood with oil, and use to cut slots..

Modifying the factory tool from Whittet Higgins is a possibility. Link : BAS Bearing Assembly Socket

Much better than a quick filing job.

Nut is a standard part, so at worst drill/chisel it out..

Note: part number may be wrong in manuals..

Link: http://www.practicalmachinist.com/vb/bridgeport-hardinge-mills-lathes/m-head-spindle-210766/
I'm sorry to hear of your flood. I don't know much about Bridgeports or the cost of bearings for them, but as to removing the nut, I will offer the following comments: 1. Make sure the lock tab is disengaged before trying to remove the nut. Sorry if this is dead obvious, but in the picture you provided, the lock seems to be engaged. 2. Make sure that you are applying force in the right direction. (Is this nut RH or LH thread?) Try tapping against one of the slots with a soft drift or pin punch, not a chisel. If that doesn't work, you may have to make a tool to remove the nut, or perhaps borrow something from a kindly member here who has one. That nut shouldn't be terribly tight and should respond to a reasonable amount of force to get it loosened.

As to the motor, I wouldn't worry too much about it, beyond the bearings probably needing replacement and perhaps the start switch needing to be cleaned. People make a big fuss over motors getting wet, especially the old ones with cloth insulation. I've never had a problem, and you probably won't either, so long as you get the motor thoroughly clean and dry before trying to run it. The motor will dry out better if you dry it while it's apart, and reassemble it once it's completely dry. Leave it near a heat outlet, or set it outside on a warm, sunny day. Do this for a couple of weeks or so and the motor will be dry and shouldn't give you any unpleasant surprises.

You are right that the single phase motor is of interest to home machinists and should be saved.

I had a basement flood the other year (clean water, the sump pump went on strike) and there was a cheap 20" box fan down there. Since the water didn't even trip any circuit breakers (110 and 220 outlets were under water!) I said what the heck and plugged in the dripping wet fan. It took off like new and blew a stream of water out the back. There were several other motors down there (boiler circulator pump, exhaust fan for the boiler, etc.) and all of them were immersed. None suffered any damage I could detect, although I didn't try to run them while wet (and don't recommend that anyone else try, either).

Totally unrelated (almost)... My basement flooded a few months ago and an am/fm stereo receiver and an external hard drive were completely submerged. I took apart the hard drive to let it dry out for a day or so and it worked. I was amazed. I did not take apart the receiver, but I did let it air dry for a few weeks and guess what- it worked, too. Both were on a GFI outlet which was tripped, so that might have helped. I'm now backing up all my data in case I'm not so lucky next time!

Good luck with the m head.