Boring To Seat A Ball Bearing

For reference, 6262 bearings are 35mm in diameter.

Can you tilt your mill head sideways, clamp the bar to the table horizontally (supporting the other end that's off the table) and machine it like you would on a horizontal boring mill?
 
Tony Wells said:
I think you can safely forget using an end mill to plunge a proper size hole for a press fit in your application. A reamer that size will be rather expensive and pretty long. And as always, there are pre-ream conditions that must be met to achieve the results you need.

The proper thing, IMO, is what others have suggested. That is a boring head. Drilled holes are seldom placed accurately in terms of assemblies where ball bearing supported components are used in the first place, even if you could somehow hit the size. Center drill or spot drill, then drill under size, then bore to finish size and on location. That's the most common approach. There are some crude, but effective, tricks to using a fly cutter to bore a precise hole that you might want to look at if you do not have a boring head.

But first, I think I'd forget using an end mill for this.
Click to expand...


Thank you Tony,

I understand Boring Head is what need. I don't have one. I will order one from LMS. Appreciate your help.

Prasad
 
What do you mean by single ball? Sorry, I have much to learn..
 
Ball bearings can be bought one at a time. Think "BB", as in "BB Gun" from the toy section. They shoot small, round projectiles. Although hardly precise "ball bearings", the concept is shared in that the main object is a single sphere that is the projectile.
There are a few uses for individual balls where there is also a need for precision, so the suppliers of ball bearing assemblies make available individual balls. One example that pops into mind is building/rebuilding a precision ball nut/screw. Clearances there are critical, and to make allowance for variations in the actual screws and nuts, precision balls with small but precise variations are made so they can be selectively assembled to yield the best quality movements.
 
1/2-5/8" bearing balls (that are accurate, measure them!) are great to use on your surface gauge to measure squareness.

EDIT: I believe I had posted this in another thread, not sure how it ended up here. Sorry for the off topic post.
 
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If you are not looking for a tight seal but wish to locate or secure the bearing, here is a process the I have used. I select and end mill smaller than the diameter but as close to the final size as I can. I then bore the primary hole. Then I offset the end mill by 1/2 the difference in the X direction. I repeat the process in the -X direction and in the plus and minus Y direction. If the difference in diameters is small, this is usually sufficient. For greater differences, I will make four additional cuts on 45º diagonals. The offsets for these cuts are .7071 x 1/2 the difference in the diameters in both X and Y directions.



As an example, if you are cutting a 1.005" counterbore and have a 1" end mill, 1/2 the difference in diameters would be .0025". If the coordinates of the center of the bore are 0,0, the four auxiliary positions would be (.0025,0); (-.0025,0); (0,.0025); and (0, -.0025). If you want to get closer, the four additional positions are (.0018), (.0018); (.0018, -.0018); (-.0018, -.0018); and (-.0018, .0018). This process would give you a minimum clearance diameter of 1.0035" for the four auxiliary positions and 1.0046" for the eight auxiliary positions.



The offsets can be increased slightly to get the proper fit. If a precision fit is desired, it would prudent to turn a set of precision test pins slightly undersized to determine the progress.
 
Please post a drawing or photo
I have machined hundreds of thousand ball bearing seats. Most had to be with in ± 0.000,2 [0.005mm] of the diameter of the ball bearing.
I do not think a mill cutter will work that well.

Dave
 
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