Deep Drilling Small Diameter Hole

I need to manually drill a 0.125 diameter hole 2 inches deep in 304 free machining stainless...... I then used a jobber length solid carbide drill, peck drilling roughly 0.100 per peck with cutting oil. I withdrew the drill every two or three pecks and added oil into the hole.The drill snapped at the top of the flutes at the same depth of the flutes.

Am I reading it right that the the top of the flutes are even with the top of the hole when the bit broke? I'm guessing about 1-1/2" deep? If so, would a bit with longer flutes help? Or maybe a gun drill if the project is worth the money to buy one? Or shorter pecks with a standard bit and blow the hole out with air or coolant between pecks?

Tom
 
At 200 feet per minute the spindle speed at .125" diameter is 6000 Rpm's.
Place an indicator on the drill shank when it is in the holder, if there is runout at the 2" depth this will cause problems with a carbide drill, if the 2" depth is very close to the holder very little runout will break the drill, carbide does not flex.
 
For deep holes, I use high helix cobalt bright drills. McMaster Carr has them. They pull chips out of the hole as your drilling.
They also have long drills with the spiral cutting flutes only on the first 3rd of the drill. Cobalt. Very strong, stiff shank.
You can also find Guhring long drills with reduced diameter tips to start the hole, cobalt. Very inexpensive. Ebay.
Not sure if they have them in .125 or less.? Excellent drills for deep holes. I have several in various diameters.
 
Sorry, but a 1/8” carbide drill bit trying to go 2” into 304 stainless, has major problems with failure written all over it. And then to compound the problem using a mini mill. You would need a very rigid machine with a flood of coolant and have fluid like translating axis’s. And preferably CNC so you can woodpecker easily and accurately. A 1/8” solid carbide drill bit will break like glass. As others have said, try cobalt.
 
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Sorry, but a 1/8” carbide drill bit trying to go 2” into 304 stainless, has major problems with failure written all over it. And then to compound the problem using a mini mill. You would need a very rigid machine with a flood of coolant and have fluid like translating axis’s. And preferably CNC so you can woodpecker easily and accurately. A 1/8” solid carbide drill bit will break like glass. As others have said, try cobalt.

I successfully drilled the hole with a cobalt drill. I used smaller pecks, completely withdrew the drill between pecks and used lots of cutting oil.
 
Glad it worked out. I drilled a 5/32" hole through 1" square 304 yesterday with a plain old HSS drill, some Anchorlube and it went through just fine. If the drill talks (squeals/squeaks) to you, increase pressure to shut it up.
 
Like the Anchorlube
 
Anchorlube works well on stainless, and most anything else. Still, I do not seem to use it unless its viscosity is needed. And that is silly, because it is easily thinned with water as needed for any job. Good product.
 
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