Needle or Ball thrust bearings??

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Mister Ed

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Hi all -
I am working on the drawings for some new lathe dials for my Logan. The dials will be 3" direct read, with a settable zero and will incorporate the original cross feed screw. I will also be adding in some thrust bearings to improve turning smoothness and help eliminate (non screw/nut related) backlash slop.

I currently have the plans drawn up using needle bearings, and then started wondering ... "should I be using ball thrust bearings"?
 
needle bearings are a lot thinner and would probably work just fine, your automatic transmission uses them!
 
Kurt vises use needle bearings on the screws and they see a lot more force then the cross slide will
 
Thanks guys. I am quite familliar with needle thrust bearings ... not so much with thrust ball bearings. I have these protected from swarf etc the best I can, however they are not in a sealed environment. But that is what gor me thinking. Are ball thrust bearings less impacted by swarf/crud.? These will be in a difficult to oil area (hmm ... maybe I can work in a small oiler and passage). In this location, I have plenty of depth room for the ball bearings.

Unless I hear other opinions, I will continue with the needle bearings, and see if I can't squeeze in an oil passage.
 
Not sure the reason but Hardinge use ball thrust bearings on the cross and compound slides. The larger rolling element might be less susceptible to swarf, and grit might be more likely to be forced out of the side of the rounded race to clear the balls.
There would be a lot more contact area on the length of the roller than the point loading of the balls, would probably give the roller a higher load rating for clamping applications such as the Kurt vice.
Greg
 
Ball bearings are rarely (if ever) used for thrust loads but are great for axial loads. Thrust bearings are usually needle or tapered roller like the wheel bearings in your car.
 
kd4gij said:
There are ball thrust bearings but thay are not what you are thinking
http://www.vxb.com/page/bearings/PROD/ThrustBallBearings/Kit8158
Click to expand...
Exactly, there are even some that are shielded ... but I do not have that much space.
epanzella said:
Ball bearings are rarely (if ever) used for thrust loads but are great for axial loads. Thrust bearings are usually needle or tapered roller like the wheel bearings in your car.
Click to expand...
Keep in mind, we are not talking any great force ... really just the movable dial getting pushed into the non movable part, by the nut holding the dial on. And RPM is limited to how fast I can crank. The necessity for the bearing is more for smoothness than for anything else.
 
Mister Ed said:
Exactly, there are even some that are shielded ... but I do not have that much space.

Keep in mind, we are not talking any great force ... really just the movable dial getting pushed into the non movable part, by the nut holding the dial on. And RPM is limited to how fast I can crank. The necessity for the bearing is more for smoothness than for anything else.
Click to expand...

A typical ball bearing has an inner race on the ID and an outer race on the OD. Your dial would be dragging on both of them. For a ball bearing to work in a thrust application it would have to be one designed for thrust like the one KD4 posted. A needle is thin whereas a ball bearing is thicker and may leave you with a lead screw that's too short.
 
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