On 19 Jun 2010 04:27:48 GMT, "DoN. Nichols"
wrote:
On 2010-06-19, Don Foreman wrote:
On Fri, 18 Jun 2010 14:40:33 -0500, Ignoramus13320
wrote:
Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?
[ ... ]
Look at
http://www.use-enco.com/CGI/INPDFF?P...MITEM=319-6567
tap guide, 325-5179. The pin is spring-loaded and reversable, the
other end is pointed.
I've got one -- and was just using it downstairs in the shop
within about the past hour. It was on the lathe with the bed turret in
place, so I swapped it into the drill chuck on one station which had
just drilled the hole to be tapped.
It says for #10 thru 1" taps but I've used mine
with taps down to 00-80. I use it both at the mill and at the lathe.
I about never tap a hole without it.
It is very nice as long as you have not shifted the workpiece
with respect to the spindle since drilling the tap hole.
I never do it in a drillpress, always in the BP. The DRO makes it
easy to return to a hole for tapping if it isn't tapped immediately
after drilling. If the holes are close together it's quicker to drill
them all, then go back and tap them all. If they're further apart
it's quicker to change from drill to tap at each location.
But for multiple threaded holes on the drill press I am more
likely to use a TapMatic tapping head with gun taps. It (the larger of
my two) was a lifesaver when I had to drill and tap 24 holes for 1/4-20
in 1/4" thick steel plate. I also had to be creative in supporting the
fairly long (24") workpiece when drilling and tapping the holes near the
ends.
I once watched a machinist tapping hundreds of holes in what I think
was a prototype Mark 46 torpedo. He did it with a pneumatic hand
drill. Zoop zoop, slick as snot. I suspected that he'd done this
before.
A pneumatic drill isn't nearly as likely to snap a tap as an electric
drill. If the tap gets in trouble the pneumatic drill will stall,
saving both the tap and the job. It still takes a steady hand, though.
I've done it with #10 and 1/4" but I wouldn't try it with 6-32 or
smaller.