BEST general procedure for drilling holes?

[Mike C.]

Sea Farmer, the reason the two flute works best is the clearance between the flutes tends to guide it less than a multi flute endmil. The reason you can cut the hole within a hole with an endmill is the reason you can't do it with a drill.

The margin of a drill has zero rake. It does not cut, does not try to cut and will not cut unless forced to (by some monkey wobbling or cranking on it with a hand drill). As soon as the margin of the drill hits something, it pushes the drill away so the point cuts instead of the sides. That is why drills make holes very close to their outer diameter (if properly sharpened) and why they cannot be used as a side mill. The margin will only rub, not cut.

The endmill HAS rake on the outer edges, which is why you can side mill with one and create those wonderful needles that embed in your fingers so readily. Instead of pushing away from the side of the work, the endmill just cuts it, making a hole within a hole. With a bunch of flutes, there will be a smaller bite taken with each cutting edge, so the cutter is likely to try to push back towards the other hole, path of least resistance.

 

[Robert Campbell Jr.]

Very funny Mike but making the leap from my: "Your machine says, "max drill size 3/4", to your: "Bob, yeah, you can worry your way through the work with a 3/4hp HF drill press," skips a few able machines, the ones I have or would have and jumps down the machinery hole to an HF anything .... not something I'd even recommend to anyone.

Example: A J-head Bridgeport,
Table:
Overall Size: 42" x 9"
T-slots: 3 @ 2.5" centers
T-slot Size: 0.625"
Table Load: 750 lbs.
Height Above Floor: 47-1/4"
Travels:
Table Travel (X-Axis): 30"
Saddle Travel (Y-Axis): 12"
Knee Travel (Z-Axis): 16"
Quill Travel: 5"
Ram Travel: 12"
Spindle:
Throat Distance: 6.75"(min.) / 18.75" (max.)
Table to Spindle Nose: 2.5" (min.) / 18.25" (max.)
Spindle Diameter: 1.875"
Quill Diameter: 3.375"
Quill Feed: 0.0015 / 0.003 / 0.006 in./rev
Taper: R8
Speed Range:
Low (infinitely variable): 60-500 rpm
High (infinitely variable): 500-4,200 rpm
Head Adjustments:
Head Cant (forward/back): 45 degrees
Head Tilt (side to side): 90 degrees
Head Swivel (side to side): 360 degrees
Capacities:
Drilling Capacity (Manual): 3/4"
Drilling Capacity (Power): 3/8"
Milling Capacity (mild steel): 2 cu. in./min.
Boring Range (mild steel): 6" dia
Milling Feed Rate:
Standard: 3/4-35 ipm
General:
Motor: 2 Horsepower, 1,385 / 1,710 rpm, 220 / 440-480 Volt, 50 / 60 Hz
Electrical: 480 Volt, Three Phase
Overall Dimensions: 64" x 60" x 84" tall

OK, that ain't a Fosdick, but we already discussed those guys. (though I hear there's one who might not be too bad, might do a 1" hole or two for free....)

Show of hands: How many have Bridgeports? How many need to drill holes? OK, now how many have Fosdicks? That many? whoa.....more snobs than I thought!

Bob

 

[kartracer55]

Thanks for all the input guys. I plan on placing an order from MSC in the near future, and I was considering center drills, but I will pick up a few spotting drills instead.

Also think I am going to pick up a Generic USA made Bright finish HSS bit set for around 50$. They have a set of thunderbits for 100, but at 2X as much, I can't swallow that just yet.

 

[Mike C.]

Bob, problem with drilling big holes with the mill is the risk of blowing out the backgears going down to the lower speeds. Also, the powerfeed is more of a milling or boring powerfeed, not stout enough for pushing a large diam drill. Of course, drilling a 3/4" hole and then boring out to 1" with a Chandler or similar boring head can be pretty quick, too. I like the Chandler and Universal boring/facing heads because you can step out your cut without having to stop the spindle. You'll play hell with a boring head in a drill press, so that's out, but it'll work in a mill and should give a nice finish.

Reason I use the HF drill press as an example is that is what 90% of folks probably have on hand. It may have a Craftsman, Delta, Jet or whatever badge on it, but they are all the same machine. Point being, a 1" hole in a material more resilient than white pine with anything like that is a royal PITA.

 

[Robert Campbell Jr.]

No problem with your reasoning Mike but my point was that most can not justify so do not have a radial drill and must use a work-a-round for the occasional large hole. For them, (us), punching a large, full diameter drill through in one pass, is not an option.

I lust after a big radial drill, regularly check them out on ebay but can't house or justify one, yet.

As to the ratio of asian drill presses to American made, I can't speak for others but I have an Atlas/Craftsman, (my first). a Rockwell Delta and my favorite, maybe my oldest, a very heavy Clausing with a 3Ph motor.

Oh yeah, I didn't say all radial drill owners were smart-assed snobs, can't, I wants to be one...... hope it doesn't change me....

Bob

 

[Mike C.]

Oh, it'll ruin you for life the first time you hit that powerfeed, lol.

I have drilled many a hole with an undersize press. I have drilled many a hole with a mill. Last set was 12 1" holes through 3 1/2" thick steel to make a motor adapter for a pump. Took the better part of two days to get it all done. Now I have a 5hp radial. Last 12 bolt pattern I did was 1 1/4" steel. From laying the part on the table to deburring was about 2hrs.

Seriously. If you have a huge hole to drill and have somebody close by with a big radial or similar, you may find it cheaper to pay a few dollars and just have the holes drilled quickly, easily and safely than to try to do them in house with the improper machine. If it's home shop government projects, time may not be a factor, but blowing the backgears on a nice mill because a 1 1/2" drill bit hung up may not be such a bargain in the long run.