How To Do Lay Out For 8 Holes

[Bill Gruby]

Jocat;

No dumb questions are ever asked, they all make sense. Without looking your question up, this is how I would find the Bolt Circle Diameter.

Assuming the 3 bolts are of equal spacing they form an Equalateral Triangle. Find the center of the Triangle and the distance from the center to one intersection is the radius of the bolt circle. From there the rest is simple math.

"Billy G"

 

[Bill C.]

After making the I.D. and O.D. use the old ring and a transfer punch.

I would make the holes, at least one hole, one size bigger just in case they didn't match up like they should. I hope you get your mill back into operation soon.

 

[markknx]

For any odd number I would guess finding the center of the bolt circle is the first step. Then it is only a matter of center of the bolt circle to the center of any hole in the bolt circle times two. There may be faster more accurate ways as I am pretty new to machinist type work but for metal working/steel fab this works. (you know like when 1/32 is tight enough.)

 

[Bill Gruby]

Here is what we know;

1) The bolts are equally spaced and there are three of them.

2) They create an Equilateral Triangle on the Bolt Circle.

3) Equilateral Triangle -- Three like Angles.

Now ------ bisect each of the three angles. Where these three Bisects intersect is the center of that Equilateral Triangle. You with me so far? From this new found center to any one of the Triangle corners is the Radius of the Bolt Circle and from here you are home free. All you need is the radius.

And some of you thought that after High School you would not need Geometry ever again.

"Billy G"

 

[jocat54]

Here is what we know;

1) The bolts are equally spaced and there are three of them.

2) They create an Equilateral Triangle on the Bolt Circle.

3) Equilateral Triangle -- Three like Angles.

Now ------ bisect each of the three angles. Where these three Bisects intersect is the center of that Equilateral Triangle. You with me so far? From this new found center to any one of the Triangle corners is the Radius of the Bolt Circle and from here you are home free. All you need is the radius.

And some of you thought that after High School you would not need Geometry ever again.

"Billy G"

Thank you Bill, now very easy to understand