calculating bolt hole pattern

G

garysue46

Registered
Registered
Joined
Feb 11, 2017
Messages
8
Without using an app. i would like formulas for calculating bolt hole circle patterns. the old way.
Thanks
 
Sine of the angle multiplied by the radius gives the Y axis position, cosine multiplied by the radius gives the X axis position from center depending on your own personal axis preferences of course.

If you require starting a hole pattern that is not at a right angle to your axes then just add the difference. As an example if one required a 4 hole bolt circle rotated 10 Deg. start a 10, calculate the next position at 100 Deg. then 190 Deg. and so on.
 
Last edited:
I have read (but never looked it up!) that these formulas are available in the Machinery Handbook.
Everyone should have one, and they can be had for $10-$20 if you look and are lucky.
-brino
 
(2Xsine(A/2))Xradius gives the chord where A is the angle between points on the bolt circle.

Had to do this with a big flange once.
Punch the starting point, and work your dividers both directions using light punch marks. Hope they meet on the opposite side. Cumulative error setting the dividers shows up badly after 10 holes or so, no matter how careful you are.

Sent from my Moto G Play using Tapatalk
 
Gary, formulae hurt my old head so this is the old fashioned way I use. Please let me know if you would like a more legible picture.

IMG_0101.JPG

From the Pocket version of the Machineries Handbook
 
Just like Brino states. Machinery handbook will show you how even when the power goes out and your DRO isn't working !
It's called education.

dickr
 
dickr said:
Just like Brino states. Machinery handbook will show you how even when the power goes out and your DRO isn't working !
It's called education.

dickr
Click to expand...

If the power goes out my mill won't run:grin: JK!
 
You must log in or register to reply here.
Back
Top