## Ball Mill Step Over Calculator

twforeman
Posts: 1351
Joined: Tue Jan 29, 2013 4:51 pm
Location: Minneapolis, MN
Contact:

### Ball Mill Step Over Calculator

If you are doing 3D surfacing with a ball mill you know about step over and the scallops it leaves. There is a diminishing return on reducing the step over value - making it smaller increases machining time without really improving the finish.

Here is a good blog post discussing the "sweet spot" for step over.

tl;dr: the sweet spot is around 1/10 of the cutter diameter, also if you can use a larger cutter it will reduce the scallop height.

Here is an online step over calculator that will show you how much scallop your settings will leave.

On most of my work I use a 1/4" ball mill and .020" step over. According to the calculator and the blog post that's a little finer than the "sweet spot". Next time I generate a tool path I'll use .025" and see if I can tell the difference.
Ender 3 3D Printer
All of my ShapeOko related blog posts

xfredericox
Posts: 292
Joined: Mon May 04, 2015 10:46 am

### Re: Ball Mill Step Over Calculator

from experience, I use 5%. 10% leaves visible ridges. Probably the sweetspot is somewhere in between those 2, but I always take 5% just to be sure.

I'd rather have the machine work 30mins overtime than having to sand 10.
Visit my blog for updates on my current SO2/lasercutting/... projects.

Posts: 8625
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15
Contact:

### Re: Ball Mill Step Over Calculator

FWIW, the CNC Cookbook article was in the Glossary entry for stepover.

I've added the on-line calculator link, and added both to the ball endmill shape section of the endmill page.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

twforeman
Posts: 1351
Joined: Tue Jan 29, 2013 4:51 pm
Location: Minneapolis, MN
Contact:

### Re: Ball Mill Step Over Calculator

Thanks Will!
Ender 3 3D Printer