Wild_Bill wrote:
A commomly practiced method for lining up a small pilot drill with the
center punch mark, before clamping the workpiece, is to:

-have the clamp set slightly loose on the workpiece (or vise),
drillpress motor off
-bring the quill down so the drill point sets into the punch mark
-move workpiece to the location where the drill point enters the
punch divot without deflecting
-set the clamp
-bring the drill point to the punch mark once more, to see that there
is no deflection
-then, with power on, drill the hole

These steps insure that the quill will push the drill straight into
the punch mark. An X-Y table won't necessarily align the punch mark
any faster or more accurately.

A basic set of layout tools and a little experience will prepare the
workpiece for accurately placed holes. The final accuracy is up to the
operator.

Hi Bill, and thank you for bringing up an issue which has been plaguing my
attempts to layout square work pieces for quite some time.

I have a small combination square, and it constructed along the lines of the
type "A" in the following figure (looking down the long axis of the base):

http://img717.imageshack.us/img717/5493/squaree.jpg

Does a proper machinist's square use a similar method of attaching the blade
along the centerline of the base? For instance, this one I am looking at
from MSC (SPI 13-626-7):

http://tinyurl.com/2cyrbvc

The issue I am getting at, is that I have trouble scribing a continuous line
around the circumference of a piece of square tubing, because a scribe line
along the edge of the blade will not line up with a scribe line along the
edge of the base (it will, of course, be parallel to it).

It would seem to me that square "B" from the first figure would facilitate
scribing a continuous line around a square piece of stock.

Are machinist's squares, like the SPI one I linked to, constructed along the
lines of drawing "B", or if not, what is the technique to use a square of
type "A" to do so?

Thanks for your help on this issue; this has been a thorn in my side for
some time now.

Jon