I recently bought an Asian lathe of eBay. I bought an MX-210V. It has a thru spindle diameter of 1.4", and needed a finished size of 1.1".
But the lathe was just about useless because of excessive chatter. I asked my brother for help, but he couldn't it out. He is a machinist, but everything is CNC for his job, so.. I've watched videos and really struggled. Then one day I was looking for loose stuff, since the videos say that's one of the causes of chatter, and I tried to wiggle the 3 jaw chuck. Tony amazement it was loose as a goose. I could easily wiggle the work piece up and down by 0.100" or more!
So I determined the bearing at the chuck is an angled roller bearing. The bearing at the drive end is a deep groove ball bearing. That makes no sense? Shouldn't the drive side bearing also be a tapered roller bearing? In spite of that I took the spindle out and examined it. The drive side bearing with the deep groove ball bearings does not slide onto the shaft very easily. It's OK up to where it is supposed to sit and the spindle gets thicker and appears to have been polished. But it's just too big to go inside the bearing. I could probably drive it on, but my understanding is I use the spindle nut to pre-load the tapered roller bearing at the chuck end. But it has to pull the spindle thru the left bearing. If it binds up then it won't do a very good job of pre-loading the bearings.
I tried using some Emory paper, but it was slow going. So I went ahead and put it together and tightened up the nut. It took a lot of force, but eventually I was able to get it to tighten up, and I could not feel any up and down slop in the chuck end of the spindle. So put it back together and it was able to cut finally. I managed to make one of the 4 pieces I needed to make.
It worked until I got to the time I needed to perform a cutoff of the 1.25" aluminum bar. Then it started to chatter really bad again, and I could see the piece wobbling really bad. I checked the up and down movement and it was loose again?
It has two nuts on the end of the spindle to lock them. So I figured they just got loose again. So this time I used Permatex Blue threadlocker on the threads. So I got it all back together again. Went to the cutoff, and at first it was ok, but it started to chatter more and more, and then got really bad again. I checked the up and down motion, and it was loose.
The nuts were almost impossible to remove with the threadlocker on them? I had to hammer them off. And the thing is, there is no way the nuts just backed off.
So I have a new set 2 angled roller bearings, one for each end.
But what is going on?
Should I just use the hacksaw to cutoff?
Should I work on the shaft until the bearing can slide on the shaft?
I took the outer race out at the chuck end, and there was a bearing cover between the outer bearing race and the casting? It's like it was being used as a spacer.
So that is my story. I guess I will try to put the two new bearings in there. But Ild like to understand how the bearing can seem tight, then get some chatter, and it loosen up?
