Five-Cent Wedding Band

Step 2 Mark the center of the coin

Use a center punch to make a starting point for the drill. You can use a nail or other pointy thing. Just make sure you get the notch in the center! If you are off, start over on a new coin.

Comments

[maxanova]

you can also use a center-finder attachment for a combination square to find the center. it works on the geometric principle describe above.

If you don't have one, use a very very accurate ruler (I have one in 100ths, they're cheap). Find the longest path across the coin, that's your diameter. Mark the middle of it.

[rrrmanion]

do both horizontally and vertically, that way you're sure.

[Londonbrig0]

Any suggestions for finding the center of the coin?

[lectronics]

the angle of the dangle... never mind wrong formula. lol ;)

[Trace II]

Well, you can use the "right angle in a circle" trick. I learned this back in geometry. When the vertex of a 90 degree angle is on the edge of a circle, the sides of the angle will cross the circle 180 degrees apart. You can mark those points, mark a line in between them, then turn the circle and repeat to get an X.

[Trace II]

Pics or it didn't happen...

[Trace II]

I can't seem to figure out how to upload pics...

[cmjake007]

if you do the triangle in 2 different spots if will give an inersection at tne exact center of the circle, yes ??

[Trace II]

There we go

[janettetsmith]

@ Trace II:

I vaguely recall this thing they called 'math' back in the day, however, it remains a mystery to me.  Bless you for creating the simplicity needed for my comprehension.  :)

[Londonbrig0]

Excellent, good ol' geometry pulls through again, thanks!

[Trace II]

I just KNEW that would come in handy some day :)

[Fire Explorer 3]

Can the angle go anywhere on the edge?

[wokwithme]

I believe so.
Simply put it:
Draw a Rectangle in the Circle with a vertices intersecting the edges of the circle. Then Draw 2 intersecting diagonals inside Rectangle. Now you have the center of the circle.
Geometry is my Fav Math subject. Can't believe I never learn this before.

[rrrmanion]

so, you fit square in the circle?

[wokwithme]

Yes you can. It's possible but you'll have to know the exact length of the Diagonals (hypothenuse) which also is the Diameter of the Circle. If Diameter, D, is known, multiply square root of 2 to D to get length of the four sides.
* Don't Forget that you need right angles at all four corners. It's probably less practical to use any of these formulas since it's hard to get right angles on a such a small coin as a nickle. Using the dimensions of a square is better but you'll really pushing the boundaries of your measuring apparatus.

[Fire Explorer 3]

Micrometer, anyone? :P

[wokwithme]

Micrometer will work. You need to elaborate. Oh well, I guess I can try.
I would measure the diameter. Then draw a Square on piece of paper with the diameter as the length of the sides. Poke a pin hole in the center of the square and then tape the coin in the square. You know the rest.