Re: [CAD_CAM_EDM_DRO] CNC drilling

Hi Ron

I always use a G73 peck cycle when drilling a large number of holes like ex.below:

G73 X? Y? Z-? R.1 F5 Q.2 a G99 on the end of this string will retract Z to R plane each peck, Q is the peck depth.
X? Y?
each hole location thereafter then
G80 cancels it

It seems that a feedrate of 5 is a good place to start for any size drill in steel and aluminum, then adjust feed over ride to suit. If I have 20 holes or less to drill, I just single cycle and pull the quill. And for any hole in aluminum deeper than an inch, always drill them manually. Theres always a sweetspot for drilling, RPM too fast or feed too slow (same as lathe)it makes long shavings that ball up on the drill. Keep upping feed and dropping RPM until they break and expel.

It's one of those things where a chart with hard numbers wouldn't really apply. The way the drill bit is sharpened, depth, coolant and of course, material all have effect on how the drilling operation goes. Start with F5 and turn the Feedover to 20% and adjust from there.

Ron





Ron Ginger <ronginger@...> wrote:
I just finished a new Jet mill conversion. In the past I have always
been afraid to drill under CNC control- Ive let the program single step
to location, then I operate the quill by hand.

What feed rates are used for CNC drilling? Do you calculate chip load
like you would for an end-mill? What is a reasonable chip load for a
drill? I suppose that varies by drill diameter?

ron ginger






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