Newsgroups: rec.crafts.metalworking
Subject: Re: Getting a hole exactly center on roundstock question
From: Robert Bastow <"teenut"@ hotmail.com>
Date: Tue, 07 Mar 2000 03:09:13 GMT

That's as good a method as I have heard Gary..with one proviso. Use a ground
center point (Every tool box should have a few!) rather than the rather iffy
point of a drill. 

Given that, you "eyeball" method meets "teenut's exacting standards" (;^)..and
will get closer than any one has any right to expect in a drill press..Closer I
suspect than a lot of people can achieve in a mill with edge finder and DRO!!

teenut

Gary Wooding wrote:
> 
> Here's a quick and easy method that is surprisingly accurate.  Put a centre
> drill in the chuck, put the bar in the vice and line it up roughly by eye,
> then place a metal rule or strip of stiff lightweight metal across the bar
> at right angles to the axis (like a see-saw made of a plank across a log of
> wood)  and lower the drill to gently pinch the rule between it and the bar.
> Chances are the rule will be forced so that one side lifts and the other
> drops - this is because the centre of the drill is not on the highest part
> of the bar.  Adjust the vice so that the rule is as horizontal as you can
> get it - the drill is then accurately centred, so remove the rule and start
> the drill.
> If you use a 12" rule as the metal strip, when it is 1/2 degree out, one end
> will be 0.2" below the other and that translates into an accuracy of approx.
> .004 x  the
> diameter of the rod.  IE, 4 thou on a 1" diam. bar.  Since 0.2" is very easy
> to see, it is quite feasible to aim for a difference of 1/16", which
> corresponds to an accuracy of around .0015 x the diameter of the bar.   Is
> that accurate enough?
> 
> --
> 
> Gary Wooding
> 
> -
> foxeye <fox@NONE.COM> wrote in message
> news:38c3acea.46011278@news.ddyne.com...
> > How does one get the drill to go dead center through the diameter of
> > round stock when drilling on the drill press. What and how is it
> > setup. I usually clamp it in a dp vise, and then using a hermorpodite
> > cal, find center by scribing  on the top of the round stock using the
> > vise jaws for parralells  or by swinging an arc from detents that I
> > have  drilled on my on my dp vise  in line with each other but on each
> > jaw. Then prick punch this intersection mark, and drill. Is there an
> > easier way?
> > foxeye