Awl--

So ahm drilling holes w/ a drill/chuck/tailstock in a lathe/5C collet, in
1/4" brass, 1.75" long.

Sequence 1: center drill both ends, 3/16 drill both ends, about 1/2" in,
then 1/8" drill thru.
Awful results; very poor concentricity of 1/8" hole at the exit end.
Drove me crazy.

Sequence 2: center drill both ends, 1/8" drill (thru, or halfway from both
ends), then the 3/16" drill.
Excellent concentricity.
Sanity restored.

I endeavored in seq. 1 because I thought the thicker drill would have
inherently less drift, and that with less resultant material for the 1/8"
drill to go thru, less drift/better concentricity.
But not so.
Others experience this?

A friend says that poor results of seq 1 is likely exacerbated by the brass
material itself, and that custom sharpening of the drills would help--sumpn
like split point, but diff, he says--hasn't shown me yet.
And also that my assumption, that the cone left by the 3/16 bit is centering
the 1/8 bit, is proly not valid.
Altho it seems to me a 3/16 drill would be an adequate spot drill for a 1/8
drill.

Any idears on this?
----------------------------
Mr. P.V.'d
formerly Droll Troll