Author Options:

How does one ensure the feed speed does not exceed the milling speed of the cutter? Answered

When milling any material, if the speed of the axis drive exceeds the capability of the cutter/stock capability rate, the stock will deform or the cutter will overheat, or the axis will jam. Conversely, if the axis is driven too slow,well, that's too slow!
 One more, all of the designs I've perused thus far are utilising phase counting to determine where the cutter is, in other words, there seems to be a lack of tracking feedback. So, how does one ensure a 4" circle is a 4" circle and not a 3.5"x3.75" ellipse?



Amateur machines rarely have position feedback, unlike the big boys, but even the big guys jam up, if you program them wrong wrt feeds/speed, and or snap the cutter. You'd have to measure the spindle current and establish how hard that was working as some measure of cutting effort.

In cam systems, the optimal and maximum feed speeds can be calculated using the spindle speed, end mill size, and material thickness.

As I recall from when I was doing it, there are tables that will assist you, but I can't remember where any of that is any more.

In simple open-loop systems: Limit speed in software, based on knowledge of how fast that bit can cut. Ideally, also factor in how many hours the bit's been in use, to allow for it getting dull. Yes, this means you cut at less than optimal speed, but that's the trade-off you accept in doing a low-cost system.

If you're doing a serious professional CNC mill, you run closed-loop with appropriate sensors.