.018 ID x .260 Deep in 360 Brass

[chipmakes]

Trying to drill this hole on a production basis (30,000) parts on a Tsugami S206 Swiss lathe. Started using jobber length twist drills because I knew I'd break a few.

The plan is to drill .0173", then ream .0180", print calls for .0180" +/- .0004"

Spot drilling with 1/8" spotting drill
7500 rpm
first peck at .001ipr, .042 deep
succeeding pecks at .0024ipr, .010deep
pull out to Z0.0
feed back in to .020 short of previous depth at .01ipr

A drill will make 0 to 20 holes. I have varied spindle speed from 5000 to 10000, 5000 was the worst. Adjusted X position by .0001 increments to fine tune the alignment ( produce the least tapered hole). It appears that the flat at the bottom of the spot drill hole from the spotting drill's chisel point is larger than the diameter of the .0173 drill. I tried a carbide drill when things appeared to be going better, but it disappeared on the first hole. Using neat cutting oil.

Questions, thought, ideas, experience, knowledge all are welcome with appreciation!

Make it a great day,
Chip

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[mactec54]

Trying to drill this hole on a production basis (30,000) parts on a Tsugami S206 Swiss lathe. Started using jobber length twist drills because I knew I'd break a few.

The plan is to drill .0173", then ream .0180", print calls for .0180" +/- .0004"

Spot drilling with 1/8" spotting drill
7500 rpm
first peck at .001ipr, .042 deep
succeeding pecks at .0024ipr, .010deep
pull out to Z0.0
feed back in to .020 short of previous depth at .01ipr

A drill will make 0 to 20 holes. I have varied spindle speed from 5000 to 10000, 5000 was the worst. Adjusted X position by .0001 increments to fine tune the alignment ( produce the least tapered hole). It appears that the flat at the bottom of the spot drill hole from the spotting drill's chisel point is larger than the diameter of the .0173 drill. I tried a carbide drill when things appeared to be going better, but it disappeared on the first hole. Using neat cutting oil.

Questions, thought, ideas, experience, knowledge all are welcome with appreciation!

Make it a great day,
Chip

Grind or buy a carbide D-Bit it will hold a .005 point for spot drilling