Bolt hole circle without a mill

[SgtMillhouse648]

Originally Posted by sanddrag

What is the most accurate and repeatable way to make a bolt hole circle on a round part without the use of a mill? I do have a lathe which I could possibly use to scribe a cicle, but I still need 6 holes evenly spaced around the circle.

you all are making this more difficult than it needs to be. all you need is a compass. scribe a circle centered on the part the dia of the pattern. then DO NOT CHANGE THE COMPASS IN ANY WAY. place the anchor point of the compass on the circle you just scribed. make an arc through the circle. then move the anchor point on the compass to the intersection point, and repeat the process. do this all the way around the circle. wahlah you now have 6 points equispaced around the circle. centerpunch the points where the circle and arcs meet, and drill

[sanddrag]

There was the word "accurate" in there.

Most compasses I've seen don't come close to even acceptable quality and you still have the problem of finding the center.

[Andrew Blair]

Originally Posted by sanddrag

There was the word "accurate" in there.

A decent compass is as accurate as the person using it. My hand happens to be a bit shakey evidently.

[Bill_Hancoc]

but still not quite the level of accuracy achieved by using (what i assume is) a quility lathe

[Dick Linn]

Dividers can be very accurate IF you can find the center and mark the bolt circle accurately. It's a matter of developing layout skills.

[John Gutmann]

What about on of those compases that have the thread shaft throught the middle and screw pen and closed.....That is if you know what I am talking about.....