CNC milling processing, how to choose the correct milling and reverse milling? What's the difference between the two

  1. feed direction.
    Because the milling cutter is rotating, the feed direction must be defined clockwise and counterclockwise.

    Look along the feed direction of the tool, the tool is to the left of the workpiece, then the feed direction is called clockwise. Conversely, when the tool is on the right side of the workpiece, the feed direction is defined as counterclockwise.for the same tool, the same route, the milling method may be different if the 20 right end milling cutter processing a long width and height for 80605 shape and processing a long width and depth for 80605 groove, if the same feed direction, the direction of the tool filling, the [milling]( method is different. 

When machining groove, the cutter in the right side of the workpiece, the feed direction is counterclockwise, the milling cutter rotation direction and the opposite direction of the feed, it is the reverse milling.

2.Milling cutter rotation direction.

 CNC milling machine can be through instructions or buttons to achieve spindle forward rotation and 

reverse, spindle forward rotation and reverse by milling cutter rotation restrictions, not spindle forward

rotation is milling, and vice versa.

As a general end mill, because most of the right, the spindle can only turn forward; Also like the left

and right screw thread knives, the spindle for the reverse and forward rotation.

  1. Difference and selection of milling and reverse milling

    The milling parts are compression, the reverse milling parts are tensile, compression smooth, easy to


Milling has a trend to let the knife, the reverse milling has a deep chewing trend, such as internal

corner had better be milling.

Processing of some soft materials, such as copper, it is best to use reverse milling, finish will be better than milling.

Due to the worktable feed screw thread clearance, milling cutter cutting force will make the workpiece
moving forward, but milling than milling can reduce tool wear, improve the surface finish, to ensure dimensional accuracy.

When the table is hydraulically driven, the workpiece blank surface is not hard, the process system to
have enough rigidity. Milling should be used as far as possible, especially for difficult materials milling, the use of milling can not only reduce cutting deformation, reduce cutting force and power consumption.

On the contrary, when the cutting surface has a hard layer, slag, the surface of the workpiece more
uneven, such as forging blank, should be used to reverse milling.

KiCad produces Gerber (and Excellon drill) files for production purposes. It does not directly produce G code to drive a CNC machine. If you want to mill a pcb, you need to further process your files outside of KiCad with a program such a FlatCam or CopperCam. I believe Eagle has a milling ULP but there is no plugin that I know of that manages this within KiCad. So your question is one for the support team of whichever external program you use.
Isolation milling is done with a low depth of cut so tool engagement and chipload are less important factors than in machining other materials. Whether you will get better results for the board cut out using climb vs conventional depends much more on your tool geometry, spindle speed and run out.

I’ve milled a bazillion PCB’s on my CNC Mill and have spent many hours testing various aspects of milling and software for PCB’s.
I recommend reader’s of this post do their own testing to determine what works best for them.

For PCB’s - some tip’s:

V-Bits can make ragged edges and you cannot control the Trace & Pad widths in a manner that is consistent.

End-Mill bits (for me) do the best. I prefer Titanium Coated Carbide.

Feed-Speed and End-Mill quality do matter.
I use 0.6, 0.7 and 1.0 (mm) bits. (0.5 break too easily but are good for specific needs). I get bits from Amazon (generally cost is around, $8 to $15 for qty=10. I prefer the Hozly and HQMaster brands.

Direction, does matter when milling (especially face milling) but, it is NOT important for PCB milling as the depth is too shallow and the cutter’s Chip relief is too small.

I prefer CopperCam. It does take a few minutes to learn the best settings and the tricks to get great results.

Example (I prefer Large pads and wide traces…)
[EDIT: Added Video]


This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.