Bolt hole circle without a mill

[Cory]

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.

Could you possibly CAD a circle split into as many equal segments as you needed, and then print it on an overhead transparency, and then use this along with your scribed circle to place the holes?

[Doug G]

Ahhh... fond memories of our early years of putting those bolt hole circles into sprockets that fit those skyway wheel hubs. The way we did it was to CAD a pattern of the bolt hole circle with center point marks for each hole and a center hole. Print out a 1:1 scale drawing, cut it out, glue it on the sprocket centered with the middle of the sprocket (hardest part), use a punch for the holes to be drilled lined up with the center points on the drawing, and drill away!!

On second thought if you use a lathe to scribe the hole circle and then an edge to scribe some lines that bisect the circle into the parts where you want holes, that may be just as easy.