Jet bd920n run out

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Brianthedriller

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This is my first post I have a jet BD 920n
It shatters very bad and I can see the Chuck moving and wobbling I’ve checked the bearing adjustment for the manual and I don’t know if I have a been spindle or bad bearings I can post a video of it running out I need help with that I don’t know what I’m doing
 
i wasn't able to view the attachment without installing another app- so i didn't see the video
is there anyway you can post to YouTube?
 
it’s hard to know where to start with this.

This could be very misleading in that you are measuring an intermediate, not the actual spindle. That’s to say, somebody could have done a bad job on mounting the chuck to the mounting plate. That also looks like the original 4 jaw chuck and they were known to be junk. Also you don’t go by the outside of the chuck body to measure concentricity, you make the piece concentric by adjusting the jaws on the 4 jaw until it is concentric with your DI.

Have you pulled the chuck and measured inside of the spindle for play/runout? Putting a 1/2” 3MT collet with a 1/2x6” drill blank in it and measuring the spindle runout/play is my preferred method.

Chatter could be so many things. Yes it can be loose or galled bearings. It can also just be wrong speed, too much DOC, or just plain old dull bit. And if you are using carbide you are working against the lathe as it might need to take a larger DOC than it can do. Lots of things to consider. Been there, gone through all those things.
 
I understand that I should indicate off the spindle my main concern is I can literally see it wobbling when spinning I only Switch to the Four daw because It is larger and showed the play more dramatically than the 3 jaw
 
Brianthedriller said:
I understand that I should indicate off the spindle my main concern is I can literally see it wobbling when spinning I only Switch to the Four daw because It is larger and showed the play more dramatically than the 3 jaw
Click to expand...
So you can see the runout with no chuck on the spindle?
 
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