Tuning pin drilling? followup

[Erwinspiano at aol.com]

If it's not too much trouble could you please explain step  drill.  I didn't 
see this one.  Are we talking about a single drill  bit with two diameters to 
it?
  Dale

Ron,

A while back you asked if I would try the step drill I am  using
(.271 with 1/2" LONG 1/4" diam step) for drilling Delignit  blocks,  
omitting
the usual cooling.

I had some time, and  fooled around with it...as I expected, uncooled,
in delignit, the bit was  cooking...uh...that would be too hot (not  
way cool in
teenage  parlance).

In the uncooled condition (and unguided) the torque results  were  
erratic, with a
40inch/lb variation.

Cooled guided  and timed, I have, in-fact, ditched the 2 step drilling  
in  favor
of the the step drill.In my set-up, it's producing very  consistent  
holes in full
thickness Delignit,
with a variation  of only 5lbs or so throughout the block (with mic'd   
pins).

For general info, I've included a couple photos of the  guiding  
rig...a very
simple idea provided by my machinist. It  drastically improves the  
accuracy of my
marginal
drill press,  when accuracy is important.

Jim I







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