Jeff Wisnia wrote:
Wooding wrote:


Here's a very simple, but surprisingly accurate method.
Place a small pointed rod in the drill chuck, a countersink bit will
do at a pinch as long as it comes to a point. Place the bar in
position as close as you can by eye and lay a flat metal strip
horizontally across it - a 12" steel rule will do nicely. Lower the
drill chuck so that the pointed end of the rod gently pinches the rule
between it and the bar. The chances are that this pushes the rule off
the horizontal because the point is not on the highest part of the
bar. Move the bar so as to get the rule as horizontal as you can get
it. Replace the pointed rod with a slocome and start the hole.

If you do the maths you will find that the rule being off-horizontal
by 1/2 degree translates into an accuracy of approx. 0.004 x the
diameter of the bar. Half a degree from horizontal is very easy to
spot when you compare it to other horizontal things around, so this
method can easily give an accuracy better than 2 thou on an inch diam.
bar.
I hope this helps.


To avoid confusing the poor OP, I gotta stick my .02 in and point out
that you've just given him a good way of drilling a hole through the
SIDE of a round bar so that it comes out close to being exactly on a
diameter of the bar.

But the OP said he wanted to drill the hole in the center of a "face" on
the bar, which most machinists would read as being the "round" end of
the bar.

Jeff


Whoops, mea culpa - I must learn to read posts properly.
I must learn to read posts properly.
I must learn to read posts properly.
I must learn to read posts properly.
--

Regards, Gary Wooding
(To reply by email, change feet to foot in my address)