View Full Version : .125 hole in 3/8" ball

Butch Lambert
01-19-2014, 03:44 PM
Need to machine a .125+or -.0005 hole through 100 3/8" balls. I haven't purchased the balls yet, but am not aware of any that are precision and not case hardened or heat treated. I believe the balls, if found, could be non heat treated as I don't think I would have a wear problem.

01-19-2014, 04:46 PM
In a collet with a backstop, drill and ream to size, just a suggestion

01-19-2014, 04:55 PM
If hardened like a ball bearing use a 2 flute straight flute solid carbide drill.

01-19-2014, 05:05 PM
If hardened the balls could be annealed before machining. The could be heat treated afterwards is the application required that.

Butch Lambert
01-19-2014, 05:22 PM
Not too worried about fixtures or holding the parts. As I understand, the casehardening is about .020 deep at RC60. I do have carbide drills and endmills. I guess the thing to do is just try a few.

J. R. Williams
01-19-2014, 05:41 PM
Steel bearing balls will be hard all the way.

01-19-2014, 05:42 PM
If you have not as yet bought the balls there is a place on evilbay that sells drilled, threaded in various matl's


01-19-2014, 05:44 PM
Butch, You might try grinding a flat smaller than the 0.125 that would get rid of the surface hardness and give a better surface to start on. I have been using the small carbide drill/mills and not having much good to say about them. A good HSS drill guided by a bushing is working better than the carbide. I just may have not found good sharp carbide.

01-19-2014, 06:46 PM
You can buy slingshot ammo that's 3/8 diameter steel balls. I know for a fact they can be drilled, tapped, etc. They may or may not be good enough for your application.

That's a pretty small hole to bore, so it looks like it would be drill and ream. The process would be greatly assisted by making a fixture to mount the ball, then guide the drill.

I've never seen a reamer in that small a size, but I'm sure they're made. You could probably use a D bit.

Butch Lambert
01-19-2014, 06:55 PM
Never thought of that Darryl. Actually I have reamers much smaller. I very seldom use them. The most important thing to me is being able to put the correct size hile in them. It really doesn't matter if it is a few thousandths off center.

01-19-2014, 06:59 PM

They have them in 1018,1045,12l14 and some others,

Butch Lambert
01-19-2014, 07:06 PM
I'm getting a lot of help here.

01-19-2014, 08:04 PM
Enco has carbon steel balls (don't buy the chrome steel ones) pretty cheap. $6.29 per 100... And you just missed a free shipping plus % discount deal last week )-:
Carbon steel balls are easy to anneal then conventional drill and ream.

Joe B