How would you do this?

M

Markusfu

Stainless

Joined

Sep 15, 2002

Location

ohio-USA

• Mar 2, 2005

• #1

Attached is a pic of a small ring which has an undercut groove on each end. Describe how you would put the groove on the two ends without opening up the ring and without using a file. I'll show a simple method after a few ideas are tossed around.

Markus

 

Milacron

Administrator

Staff member

Joined

Dec 15, 2000

Location

SC, USA

• Mar 2, 2005

• #2

What are the accuracy requirements ?

 

W

winchman

Stainless

Joined

Jun 19, 2003

Location

Thomasville, GA

• Mar 2, 2005

• #3

Make a cutter to fit in the inner race of a thin ball bearing. The cutter would look sorta like a threading die. Drive the inner race and cutter with an O-ring belt. Pass the bearing/cutter assembly through the opening, then move the ring back and forth to make the cuts.

Probably too complicated, but I think it would work.
Roger

 

M

Markusfu

Stainless

Joined

Sep 15, 2002

Location

ohio-USA

• Mar 2, 2005

• #4

Don- the accuracy requirements are not crucial. Several thou would be fine. The ring must fit the end of a pocket watch to hold a chain,fob whatever.

Markus

 

rivett608

Diamond

Joined

Oct 25, 2002

Location

Kansas City, Mo.

• Mar 2, 2005

• #5

I know they make a special little watchmaker's tool for that.... it is on of those things that fit in a vise with a little crank handle and a bunch of gears driving different size cutters..... I think they are called Pendent bow mills.... Crom shows some in his book (in other words I cheated and looked up the name)......

To do this without the gadget, there must be a trick which I hope you will share with us because I can't think of it....

 

R

Ralph_P

Stainless

Joined

Jan 14, 2003

Location

E. TN USA

• Mar 2, 2005

• #6

A OD reamer should work, or maybe a tool copied after a wooden dowel maker.

 

D

damonfg

Titanium

Joined

Apr 23, 2003

Location

Portland, ME, USA

• Mar 2, 2005

• #7

Bridgeport with a rotary table and quillmaster right angle.

 

J

Jim Williams

Stainless

Joined

Oct 3, 2002

Location

Grant, Florida

• Mar 3, 2005

• #8

Markus,

I would use my watch bow cutter, if I could find it in all this mess.

Jim

 

K

kap pullen

Cast Iron

Joined

Jan 4, 2002

Location

Maryland

• Mar 3, 2005

• #9

Mark,

In the flat, and roll it up to a circle.

Made many a stainless "U" bolt that way.

Or open it up sideways, like a spring,

and use a hollow mill.

kap

 

rklopp

Diamond

Joined

Feb 27, 2001

Location

Redwood City, CA USA

• Mar 3, 2005

• #10

How about making up a forming die and cold-forming/heading/coining the ends? It looks like the opposing shoulders are nowhere near parallel, and the axes of the cylindrical parts may be neither parallel to each other nor perpendicular to their respective shoulders. This suggests that they were not formed by a hollow mill type operation. How circular are the cylindrical parts?

 

K

kap pullen

Cast Iron

Joined

Jan 4, 2002

Location

Maryland

• Mar 3, 2005

• #11

Ok Markus,
Now let's see your way.
You promised!
Kap

 

N

Neil

Hot Rolled

Joined

Jan 1, 2005

Location

Lockport, NY

• Mar 3, 2005

• #12

Make a small stick of brass a bit shorter than the ID of the ring.
Drill a hole in it about the diameter you want, cut it in 1/2 with a jeweler's saw.
Put some smaller holes in it so you can wire it back together with safety wire (.030)
Put some coarse lapping compuound in there with the safety wire loose until it has bitten in enough to tighten it.
When you can't go any further, you are there. Put in some finer lapping compuound to polish it if you want.

 

W

winchman

Stainless

Joined

Jun 19, 2003

Location

Thomasville, GA

• Mar 3, 2005

• #13

Yeah, Markus, give it up!!
Roger

 

M

Markusfu

Stainless

Joined

Sep 15, 2002

Location

ohio-USA

• Mar 3, 2005

• #14

OK - a couple of you already figured it out. You simply put it in the watchmaker's bow undercutter jig which consists of various sized undercutters. You put one end of the bow into the undercutter while the other end is under tension with a spring that is hidden inside the brass tube . I also apply force with my thumb while cranking the handle. Kind of like a specialized pencil sharpener. I love specialized gadgets!!

 

S

simplygeorge

Aluminum

Joined

Sep 19, 2004

Location

northeast

• Mar 4, 2005

• #15

OK, I totally misunderstood...

When you said "...a simple method..." , I was waiting for a practical solution with a paperclip and scissors, or something that would make me say, " oh yeah, why didn't I think of that."

Not an obscure specialty gadget...

 

K

kap pullen

Cast Iron

Joined

Jan 4, 2002

Location

Maryland

• Mar 4, 2005

• #16

Yea,

I could have designed and built that in about a hundred years spare time.

That's a really neat tool.
Thanks for the pictures.

kap