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Benjamin Borowsky
07-19-2006, 03:27 PM
I have a number of ball bearings (6 mm) that I need to machine down to .22" ONLY around one diameter, creating lozenge or tic tac shaped thingamabobbies. I have no idea how to hold these in order to do the machining... Any thoughts? Thanks in advance,

Ben Borowsky

snowman
07-19-2006, 03:39 PM
you are only taking off 16 thou!

All of my methods would involve a toolpost grinder at that small of a diameter.

Basically making a small brass cup on headstock side, and for live center side, sandwiching the bearing between the two with a little pressure, then spin it while grinding the 16 thou off. With enough pressure, you could probably turn them....but they will be hardened too, so I doubt it.

Benjamin Borowsky
07-19-2006, 04:08 PM
Thanks for the response, snowman - the bearings are made of plastic, so I don't have to worry about hardening - I like the idea of the cup, though.

Evan
07-19-2006, 04:19 PM
Plastic ball bearings???

Benjamin Borowsky
07-19-2006, 04:43 PM
They are actually airsoft pellets that I want to try in a bb gun, 22 caliber... I was just simplifying the story.

Evan
07-19-2006, 04:52 PM
I was just simplifying the story.

Uh huh. Didn't work :D

Just hold them between two small pieces of tubing. Make one really short and fit it over the end of a live center.

Benjamin Borowsky
07-19-2006, 04:59 PM
Sounds good - I'll let you know how it works out. Thanks again,

B2

snowman
07-19-2006, 05:02 PM
please dont shoot your friends with airsoft pellets from a 22 air rifle...it will still hurt, and possibly maim

smagovic
07-19-2006, 05:38 PM
I have vacuum chuck for my woodworkig lathe, would that work for you? Basically it is 2 tubes with a ball bearing connecting them. One end of this gizmo gets connected to a vacuum cleaner, and the other end attaches to the back of the holow shaft of the lathe. What you put on the working end of the tube/shaft is up to you. It has considerable holding power, namely for something so small and light and smooth as the plastic ball you are talking about. I use it to attach blocks of wood for turning. I like Evan's idea too with the two tubes, it seems really simple. Vic

rantbot
07-19-2006, 07:30 PM
Plastic ball bearings???

http://www.kmsbearings.com/pbb_rams.htm

Evan
07-19-2006, 07:46 PM
Yeah, but they have SS balls. You can special order plastic ones but the only plastic balls I know of in general use are these.

http://www.neuticles.com/index1.html

J. R. Williams
07-19-2006, 08:40 PM
Ben
Bore a hole in a piece of steel and push the plastic balls thru to reduce their diameter.

JRW

IOWOLF
07-20-2006, 07:19 AM
Yes , Swage them.

Benjamin Borowsky
07-20-2006, 09:54 AM
I will try swaging first, and then the tube idea... And I'm making them to chronograph first - I KNOW they'll be fast, and want to see how fast before I try them in a game. If they are reliably too fast, I'm going to try some barrel modifications to see if I can slow them down to 550. Thanks for all your help, guys, I really appreciate it.

B2

BobWarfield
07-20-2006, 11:30 AM
While we're on this subject, how would you go about holding and grinding a larger (say 1/2") ball bearing in order to grind a flat on one?

I want a few to use with my Kurt vise for holding irregular work when I want a single point of contact.

Best,

BW

Evan
07-20-2006, 11:42 AM
Visegrips?

Forrest Addy
07-20-2006, 12:11 PM
For the record, a "ball bearing" is an assembly. It took a few posts to realize in this thread the poster was referring to a ball.

Benjamin Borowsky
07-20-2006, 01:52 PM
For the record, it only took one post to realize that the original poster doesn't know what he's talking about.

snowman
07-20-2006, 02:20 PM
While we're on this subject, how would you go about holding and grinding a larger (say 1/2") ball bearing in order to grind a flat on one?

I want a few to use with my Kurt vise for holding irregular work when I want a single point of contact.

Best,

BW

How will you be grinding? Surface grinder? Drill or bore a hole of matching diameter, just slightly deeper than the diameter of the hole, that way it is mostly seated. If bench grinder, vise grips :)

pcarpenter
07-20-2006, 05:23 PM
Bob-- I don't know if it would be precise enough to make multiple balls with exactly the same size flat, but I would think a hole bored ever so slightly undersized in a piece of wood would allow you to press the ball in and have some grip on the ball. A smaller through hole in the bottom of the larger hole would allow you a way to pop it back out.

Good point Forrest....sometimes we misuse a term until the misuse becomes popular...and then we no longer have a way of differentiating things.
Paul

Evan
07-20-2006, 05:46 PM
If you want to hold a bunch of bearings for accurate grinding in a surface grinder then make a plate with holes slightly smaller than the diameter of the bearings. Clamp, screw or otherwise fasten it to another plate to hold all the bearings securely. Grind.