seized live center

[rsulli16]

hi
had an interesting thing happen to me yesterday. i think the bearing in my live center siezed for a moment. it caused the mandrel to twist off somehow, instead of just spin and squeal. well in an instant the mandrel was bent and twisted around the bed ways, bent like a twig!! i couldn't believe it.
it had been making noise, and i had to constantly tighten up on the tailstock recently. the center kept stopping.
it was impressive, to say the least. one second turning as normal, in the blink of an eye a quarter inch steel rod all twisted and bent like that.
i guess it was the tool rest acted liked like a shield, nothing hit my hands, still have all ten, and they can still wiggle.
so now i am stalled waiting for a center, ordered a good one this time from johnnycnc. the one i had cost 15 dollars from amazon. live and learn.
and wouldn't you know it, i had my first craft fair sunday, did ok for a first attempt i think, cleared $180, sold twelve pens,a bottle stopper and one seam ripper , what i was working on, is my first order! fellow at the show brought a long click in yellow box elder, and wants another in dark cocobolo, as he was buying, another guy bought the other one i had on display in cocobolo, so he asked if could get him another, said sure!! i already got johnnycnc's shipping notice, sure hope PSI hurries up with the mandrel. this time i got the better one, without wrenchs, well i hope it's better. gonna give between centers more effort too.
enough for now, pay attention to noises you heard, don't let it happen to you
Sulli

 

[Monty]

When you get the LC from Johnny forget the mandrel and turn between centers.

 

[sbell111]

When you get the LC from Johnny forget the mandrel and turn between centers.

Unless you prefer turning on a mandrel as many of us do. In that case, continue doing it the way that you prefer.

 

[studioso]

Just so you know, many live centers have 2 holes in the back, which I believe many said that they are meant to oil the bearings inside.
You might need to do that with johnCNC's lc as well.

I still can't picture how a seized lc bends a mandrel...
Are you sure you are not tightening the tailstock too much? 'cose I think that on my lathe what would happen is that the mandrel would keep spinning like it would be a dead center...

 

[rsulli16]

hi
i dont know either, like i said it happened in the blink of an eye. somehow it came off the dimple on the end of the rod, so it couldn't have been too too tight, then i am guessing it walked around the center, while the center was froze.i only use finger pressure on the knurled brass nut on the mandrel, i dont think i over tightened it that way.
you know, it never was smooth rolling, right from the start, but when i got it, i didn"t know anything about this at all. i can still spin it by hand, but it's rough, not a smooth turning at all. I am not taking any more chances with it, i will wait till the new one comes.
I also dont have between center bushings for all the kits i do, so i will be doing it both ways now, i have a set of 7mm between center bushing. but i will be moving towards between center more and more i think
Can i use a drill or something to put 60degree bevels on the bushing i already have? anyone? or is it best left to a machine shop, or better to just buy new ones?
Thanks for all replies
Sulli

 

[glen r]

If its rough when you turn it the bearing(s) is gone. This happens when the bearing is not lubricated. Most good live centers, including the ones from Johnny C, have a sheet that tells you to unscrew the screw at the end of the taper and put a few drops of heavy (differential type) oil into the opening, then put the screw back on. This should be done regularly, depending one the amount of use.