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nopriors
07-01-2011, 06:34 PM
Can I drill with a 90 1/8 spotting drill right through 1/8 6061. I'm drilling about 48 holes every 1/4" for an indexing bar? I'll be chucking the spotting drill right in an 1/8 R8 collet. All comments appreciated except the ones about my hairline.

Bob Ford
07-01-2011, 06:40 PM
If the flute length is long enough I see no problem.

Bob

Toolguy
07-01-2011, 07:02 PM
You will need some kind of cutting fluid or the drill will seize up and snap off.

macona
07-01-2011, 09:16 PM
I use spotting drills for thin stuff quite often.

mochinist
07-01-2011, 09:17 PM
it will probably work, but the better way in my opinion would be to use a stub drill or make your own stub drill out of regular length drill bit, and just forget about using the spot drill to start the hole, the shortened drill will hold location fine for a drilled hole.

smalltime
07-01-2011, 09:23 PM
Should be just fine.

Just back off on the feedrate, spotters have a very thin chisel point, and this can be chipped easily.

bobw53
07-01-2011, 10:38 PM
Check the flutes on a spot drill and compare them to a "regular" drill.

There is no relief, so once you get past the point, you're rubbing.

Can you, yes... Should you, No. Have I? Of course, I've also twisted off a
5/8" spotter that seized in an aluminum hole, not even very deep.

I'm more comfortable using a spot drill improperly in steel than aluminum, it melts at a much higher temperature.

If you're looking at 1/8", check out the carbide circuit board drills, you'll be able to just slam through it, and they are pretty reasonable priced.

If its a need to do it now and this is what you have on hand, just make sure you are lubed up, surface speed is going to be pretty low with such a small drill anyway, 98% chance you'll be OK.

BadDog
07-01-2011, 10:48 PM
it will probably work, but the better way in my opinion would be to use a stub drill or make your own stub drill out of regular length drill bit, and just forget about using the spot drill to start the hole, the shortened drill will hold location fine for a drilled hole.
I agree. In aluminum, I usually just use 4 facet web-thinned "stubbies" or split point "screw length" with no spot needed. I wouldn't want to use a spot drill with any thickness more than something like 16 ga. as it's got no clearance and no chip handling ability.

Frank Ford
07-01-2011, 10:53 PM
I have an occasion to drill holes like that, and I've had great success with the
"body drills" from McMaster-Carr. 1/8" ones are less than two bucks each for double ended drills. I like the double end because the flutes are shorter so it's a bit stiffer. Split point means they don't wander, and max hole depth is around 1/2 inch.

McMaster-Carr # 3163A54

Boucher
07-01-2011, 11:37 PM
Enco has some carbide mill/drills that have worked well for me in a similar situation.