First, I apologize for asking how to cut metal here. I know its normally not done, but didn't know where else to ask.
I've never used a center drill in my CNC mill, but have an application where it would save a lot of time. What speed feed and peck would you use on a #3 center drill. The drill part measures about 0.105".
MAJOR penalty for breaking drill in part.
I'm thinking you should treat it based on the minor drill size and ignore the larger portion. Possibly it would be better to use one of the stubby single dia center drills rather the the combined?
Yes! (the voice of sad experience here...)
Many people use too high of a feedrate. That snaps the small portion of center drills more than anything.
If you can, it's safer.
OP lost
While center drills are extensively used for spotting these are not the correct tool for the job as the small drill on the end is prone to snapping off. Not only do you break a tool, frequently the "tit" is embeded/jammed in the work piece entailing yet more work to remove.
Proper tool is a spotting drill. Most any good mill supply should stock. URLs are for illustration/example. Unless you are machining some special alloy or are in volume production HSS should prove adequate. Cobalt and carbide are more wear resistant but are also more brittle and prone to chipping (and cost much more)
also see
Excessive runout greatly exacerbates this problem
What kind of metal? Is the working part steel, brass, aluminum, titanium, or.....
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I've never used a center drill in my CNC mill, but have an application where it would save a lot of time. What speed feed and peck would you use on a #3 center drill. The drill part measures about 0.105".
MAJOR penalty for breaking drill in part.
Its a medium carbon steel 8744??? or HSLA. (my son's term) It falls off his laser at work and lands in his pickup. Happens to be cut just to the shape I need :)
ME consultant teels me 2500 (I imposed speed limit) and 11.8 IPM on a .105 drill. This gives a chip load of .0048 (IPR) Like Ed says ain't no way I'll run the feed that fast. ME doesn't say a thing about peck length.
I think I'll play in the manual mill and just get a feel for it. I use a center drill in the lathe fairly often, I don't turn the speed up and feed it real slow.
Karl
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