How hard can I push a drill ?

[bigtoad170]

I have a bridgeport series II heidenhain cnc
I'm making parts with just clearance holes for bolts everything has been running great I was just wondering how much harder I can push the bit I'm new to cnc but experienced manual machinist so i'm used to going by feel and how tired my arm is, here are my conditions.
1. .400 drill (inches)
2. flood coolant
3. 1018 cold rolled steel .750 inch thick
4. peck drilling .060 peck feed rate 15 ipm
I think this maybe a little conservative but the chip looks good and it sounds good I guess there probably formulas in the machinist handbook but its Sunday and feeling pretty lazy. Plus just asking people with experience has proven more worthwhile ( most of the time)

[cam1]

Hi: Bump up the rates, and experiment a little. Worst you will do is spin the bit or break it!

regards

[g-codeguy]

.06 DOC is awfully shallow for a drill of that size. Pecking takes time. Can you increase the peck depth, and still have the chips clearing? Based on your drill size and what I would run the drill in IPR, I would say you are running a carbide drill. Otherwise I think you are already running a pretty hefty feedrate. On a lathe, I would be running a carbide drill of that size to that depth in one shot.

I've never run a mill. I am basing my comments on 23 years of programming/setting-up/running lathes. I would like to know what values you finally wind up with. Just for the sake of gaining a little more knowledge. Thanks.

[bigtoad170]

g-codeguy
No actually I'm just running a cobalt stub length drill but my feedrate calculation maybe wrong I have an old heidenhain and to be honest I'm not sure how the feed rate is measured ( sorry cnc newbie ) my number in the last post must be wrong because it almost seems painfully slow so I'll figure out the true feedrate I'm running
Yes I can bump up the pecking depth I'll try half way first (.375) and make sure the chips are clearing.
I'll keep you posted on what I figure out

[RMARCH]

Originally Posted by bigtoad170 g-codeguy No actually I'm just running a cobalt stub length drill but my feedrate calculation maybe wrong I have an old heidenhain and to be honest I'm not sure how the feed rate is measured ( sorry cnc newbie ) my number in the last post must be wrong because it almost seems painfully slow so I'll figure out the true feedrate I'm running Yes I can bump up the pecking depth I'll try half way first (.375) and make sure the chips are clearing. I'll keep you posted on what I figure out

When i peck drill i usually only peck the diameter of the drill and i never have problems.

[Mazaholic]

The depth of the peck depends on what type of peck cycle your using.
If you are cutting and retracting out of the hole,you need to take deeper cuts.
If you are just breaking chips..cutting 60 retracting 15 and cutting 60, you can ramp up the spindle speed quit a bit. and possibly the feed.
I'm assuming your drilling thru some kind of flange,if so,and it's not very thick,you can use the chip breaking cycle and get pretty extreme with it.

[g-codeguy]

Originally Posted by bigtoad170 g-codeguy No actually I'm just running a cobalt stub length drill but my feedrate calculation maybe wrong I have an old heidenhain and to be honest I'm not sure how the feed rate is measured ( sorry cnc newbie ) my number in the last post must be wrong because it almost seems painfully slow so I'll figure out the true feedrate I'm running Yes I can bump up the pecking depth I'll try half way first (.375) and make sure the chips are clearing. I'll keep you posted on what I figure out

What RPM are you running? Does your program really say F15.? Not trying to be smart here, but you do know the formula IPM=RPM*IPR...right? I hate asking such a simple question, but, when talking about computer knowledge, you have to ask me the simple ones. Figured I'd cover a couple bases this time.

[dertsap]

best thing to do is look at the drill manufacturer's recommended sfm for the specified materials your running , typically if you go beyond that you face premature wear , chipping or fatigue which will result in premature tool breakage

[bigtoad170]

I took Rmarch advice of pecking the Diameter of the drill That worked great I'll use it for a rule of thumb.
G-code guy
I'm green at gcode I'm just starting to figure out the feedrates right now am going by trial and error but want to know the correct way so I'm running 1000 rpm .397 drill then in the canned cycle it ask me for the feedrate so I typed in 150 to see what happens and it was moving in my mind at a good rate it was making a good chip not spinning in the holder and the surface walls don't look chewed up and scored. So my question is what is the 150 really telling me as far as feedrate? I originally said 15 because when milling I was told when putting in a feedrate of 200 in a linear interpolation that equates to 20ipm I realize that there is a difference between drilling and milling but the light switch in my head hasn't turned on for the feedrates.

[Mazaholic]

It depends on your machine,but most machine centers use IPM as a standard format for feed.
I believe G95 will put the machine into IPR.
RPM x IPR = IPM

[eKretz]

If you are running at 1000 rpm and 15 ipm, you have a feed rate of .015" fpr, which is adequate for a drill of that size. You COULD push it a little harder, if you are in a great big hurry, but tool life will probably suffer.

[KyleH2]

15IPM on an HSS drill seems pretty fast to me, but I only have a year experience or so.