Slot milling insight

Same basic technique is used on CNC mills. Referred to as ramping in or helixing in, depending on whether its a straight line or a helical entry.

It allows you to plunge with a non center cutting end mill, as long as you go sideways enough that you keep the center of the end of the mill clear of material.

Cheers Trevor Jones

If you lived in a cave, you wouldn't have to worry about tracking in chips!

GWE

Although I have been doing that for years, I never knew this technique had a name. The rate of plunge is a factor of edge clearance at the bottom of the tool. The bigger problem I find when milling slots like that is chip removal. How do others solve this problem? My solution is to use compressed air. Is there a better one? Steve

I won't say it's better, but I like the micro coolant system that utilizes compressed air to deposit a microscopic flow of oil based coolant onto the cutter and does a fair job of clearing chips.

I hate cutting the same chips over and over and over again.

AC

Yeah, but if you cut them *often* enough, there won't be *any* cleanup..... Ken.

This piece had through holes at the ends of the slot.

Keeping the down feed small enough that the end mill won't pull to the side very much. The down side of it is that the tool will need re-sharpening much more quickly because it's doing all of the work on the corner of the teeth instead of the flanks.

Mark Rand RTFM