Why'd my spindle seize up?

[garagemark]

I just posted this on PM as well, but more thinkers are always better, so...


Just toolin along (no pun intended) on my 9" South Bend A, and all of a sudden the spindle seized up. No noise, no warning. Just stopped. And it was quite tight untill I got it apart.

Took it apart, and found nothing really wrong. Bearing surfaces look good, spindle looks good... with the exception of one tiny spot. Yes, a round spot; about the size of a small case "o" in size 8 font. A little itsy bitsy spot that can catch my fingernail. But that's all.

Why, and how? The oil wicks are fine, though I will change them now just for sh*ts and giggles. So is it possible for a small piece of crud or a chip to get in between the spindle and the bore? I've been doing a lot of aluminum of late, and the stuff seems to go everywhere.

I just don't know where to look or how to prevent it in the future. It scared the royal zap out of me though. It just stopped.

Any ideas?

Mark

Oh, and I could use a source for the new wick assemblies, springs and all.

THX.

[Davo J]

Mark
If you were cutting aluminium you would have been using higher speeds,maybe the bearings and spindle ran dry heated up and seized.
Davo

[SGW]

Are you using the proper weight oil? About #6 or #7.

[J Tiers]

it does sound as if a piece of "something" possibly bearing surface, possibly not, was "picked up" and then jammed the spindle. It might take only a small piece

Possibly a small area that was higher than the rest "dried out" earlier. it might then "pick up" and jam the spindle.

Do you have a clearance that is at the low end of the acceptable range? While that may perform slightly better, it may also have more tendency to squeeze out or "shear out" oil at higher speeds.

The recommendation is often to slack the bearing caps when running faster, as you would with aluminum.

The idea of "running dry and 'seizing" in a general sense is probably not what happened, since that should cause galling, grooving, and overall more damage.

[Evan]

Chances are you have (or had) the lash/preload adjuster on the left end of the spindle too tight and/or it ran dry. It sets the preload on the thrust bearing on the left inside end of the spindle. It is strictly a friction bearing between the adjusting collar and the end of the spindle housing and if too tight it can easily seize, especially if you don't oil it when you fill the oil cups.

The spindle should be oiled, in order from right to left, a few drops at the front of the plane bearing between the chuck register and the cast iron housing, right oil cup filled, under the flip up cover between the bull gear and the cone pulley lock pin, the centre oil hole for the cone pulley to run free on the spindle in back gear, the thrust bearing, the left oil cup and the left preload/clearance adjuster on the tail of the spindle.

[garagemark]

I got a little static on the PM thread about being vague, so let me copy my elaboration a little bit here. Please disregard the sarcasm. The other guy kind of wrankled me a bit first thing in the morning...


I have a South Bend 9" A model. So I thought it best to post this in the South Bend section.

As far as I know, back gears don't fall into place. At least mine do not. A conscious effort must be made to push a pin and pull a lever to get into back gear. It was not.

There was not a crash, nor was I even taking a deep cut. I was feeding by hand, with the lead screw turned off. So no gearbox was turning. I was in the middle of a piece, not close to the chuck. The spindle JUST SEIZED (that means locked up to me) for no apparent reason- thus my head scratching. The spindle would only move with two heavy hands, and almost required a wrench to turn. It was not hot. It was not oil starved. I was running fairly fast rotation, but no heating was detected at all. It is cool now and still too tight. No I don't yank engines until I do extensive investigating. I know of no one that does, unless their dim bulb coefficient is way out of whack.

Once I determined that the spindle was indeed seized, I removed it from the bore. I turned it around and inserted it backwards to check the tail bore for tightness. It was perfect. When I reinstalled the spindle in correct orientation, it was still tight, though not as bad as it was last night. So I will be inking the bore tonight to check for clearances (it has no bearings, just cast bore). I will be able to clean up any problems that I find. Like I said, the spindle looks almost brand new, sans the “spot”. The bore looks nice as well.

There does seem to be a longitudinal seam of some type in the large bore, about 2/3 back from the chuck end. It appears to be a factory look, not a repair or retrofit. Never seen anything like this, but it appears to have little bearing on the issue. I can see the same line bore marks on it as well as the rest of the bore.

I have never encountered an issue like this, other than in my race car engine. At least it WAS oil starved. That’s why I ask if there is ANY WAY for a chip or dirt to get in between the spindle and bore. Never heard of it before, but I’ll just add that to the list of things I haven’t seen before.

I am using a 10 weight spindle oil (Velocite). I keep it topped up before every session. My poor old lathe is like an old man in a wheelchair. It must be taken care of constantly.

This is a head scratcher for me guys. I may be new to actual machining, but I am not new to bearings, lubrication, speeds, oil starvation, oil types, tolerances, burrs, and so on. I have built many racing engines, and in all fairness have had a failure or two. But at least I found out why and corrected the issues. Hard to repair/ correct when I have no clue.

[Evan]

I suspect you missed my post as you were typing yours.

[garagemark]

I did miss your post Evan. And I learned something too. I will now change my lubricating habits.

Somone else also lamented on using compressed air for cleaning the machine. I could very well have shoved a piece of aluminum under the cap... I think.

One thing that did help me was the fact that the old leather belt slipped well when everything came to a halt. A VERY nice feature for a new machinist wanna be. Crashes are at least a little less likely to destroy the whole shootin match.

It'll all be good now I think.

Thanks guys.

Mark

[andy_b]

yes, leather belts are a great safety feature for us newbies. i've had the belt slip several times on my SB 11.

one note, you shouldn't use compressed air anywhere around your machines. it tends to blow debris INTO the machine instead of off of it.

andy b.

[Black_Moons]

Buy the cheapest shopvac you can find, about $40 if you look around, and use that to vacuum up debrie insted of blowing it into the machine. You can even make little crevis adaptors (just don't use em to long without an air bypass, those cheap shopvacs burn out if you overload em for too long) to get into small spots. I made one that doubles as a great solder sucker