Slot milling insight

I watched an old timer mill a 1/4" wide x 1" deep x 1" long slot in cold roll. Using a 4 flute 1/4" end mill, cranking the table across and up at the same time. Each traverse to 1/4" holes drilled at each end of the slot, he cranked the table up about .030". Kind of like a switchback. The result was excellent, the slot was smooth, straight and .003" oversized. I'd never known of this technique, do I live in a cave?

Reply to
Tom Gardner
Loading thread data ...

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

Reply to
Trevor Jones

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

GWE

Reply to
Grant Erwin

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

Reply to
Steve Lusardi

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

Reply to
AC

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

Reply to
Ken Sterling

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

Reply to
Tom Gardner

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

Reply to
Mark Rand

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.