Atlas 618 - Timken Bearings

pontiac428 said:
When treated well, those bearings can last for life on a hobbyist's duty cycle.
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I agree 100%.
If you think about the tapered wheel bearings on the front end of a passenger car, they seem to last forever.
Well lubricated with the proper oil, I would think bearings in a quality lathe used by a hobby guy would indeed last for generations.
My lathe has the Gamet bearings. Going strong for over 50 years.
 
In 45 years as a factory auto mechanic I have seen only one properly installed bearing fail when the inside seal came out. ALL but that one, the failures were due to over-tightening the bearings, most had new brakes installed by the "lifetime warranty" scammers. It's really easy to work on a car, it's a little more difficult to work on a car properly.
 
markba633csi said:
The collar on Atlas usually has a small setscrew to lock the collar in place- and there is a small brass or copper slug under the setscrew to protect the spindle threads. You can sub a small chunk of thick copper wire if the original slug is missing
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markba633csi said:
The collar on Atlas usually has a small setscrew to lock the collar in place- and there is a small brass or copper slug under the setscrew to protect the spindle threads. You can sub a small chunk of thick copper wire if the original slug is missing
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I’ll do exactly that! Great idea with the copper wire!
rabler said:
Just to correct myself from earlier: what the bearing preload really controls is how much deflection occurs under applied load, (how much radial and axial play the spindle has). So it isn't the true runout (deviation from round when turning). You put a DTI on the spindle and apply radial pressure to see how much the DTI deflects. Actual runout is a function of several other things, although insufficient preload on the bearings will add to that. Too much preload wears out the bearings, pretty quickly/dramatically if the preload is really excessive. Which is why getting the right preload is important.
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Ah, good explanation. Thanks. I will revisit this tomorrow when I am hopefully reassembling the headstock.
 
from memory the procedure I used (which I think is in the manual, maybe) is to tighten the collar at the back end of the spindle until the chuck can make only one revolution when given a decent spin by hand, then back the collar off by two teeths worth of rotation. So mark some part of the spindle and unscrew the collar enough for two teeth to pass the mark. That seemed to work for me. I gave each bearing a couple of good squirts of hydraulic jack oil every use and they went onto the next owner (friend of mine now) in just the same condition.
 
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mattthemuppet2 said:
from memory the procedure I used (which I think is in the manual, maybe) is to tighten the collar at the back end of the spindle until the chuck can make only one revolution when given a decent spin by hand, then back the collar off by two teeths worth of rotation. So mark some part of the spindle and unscrew the collar enough for two teeth to pass the mark. That seemed to work for me. I gave each bearing a couple of good squirts of hydraulic jack oil every use and they went onto the next owner (friend of mine now) in just the same condition.
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That all makes good sense, thanks. I do have some DTE 26 for the bearings that seems to work good. I believe it is equivalent to some hydraulic oil. Will hopefully reassemble it tomorrow as I didn’t get a chance today. I still have to make a copper plug for that collars’ set screw to sit down on too.
 
Or a piece of lead shot, an aluminum plug, brass, anything non-marring that won't compress more once set!
 
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