Cross Hole Drilling In Rod Stock

[HANK METZ]

While the method depicts metal as the material being drilled, it is the same means of boring serial holes in wood or other round products, this just happens to be parts of a DIY CNC machine tool I’m making and thought I’d share it after a very successful and accurate outcome. The principal is quite straightforward; find the top dead center of a round using a simple shopmade “V” block. Spot drill, bore to desired diameter, repeat as described below.

Step 1 is to obtain a short piece of flat metal to serve as the indicator, and a centered pointer of appropriate size to act as a fulcrum. Apply slight downward pressure of the quill and observe the flat for parallelism to the fixture.
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Adjust work and fence to make the flat parallel, thus top dead center is found.
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Fasten a deadweight through a previous bore, let free hang to ensure a vertical lineup of sequential holes for boring.
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Just a note in closing, this method resulted in my aligning a pair steel rails for the “X” axis of my machine with about a 3 thousandths (.003) deviation over the 24” length.

[Terry Beadle]

Niffty!

There's also a video on youtube that demonstrates using a washer on a piece of wire that helps you drill long or deep holes
by keeping the dangling washer on the wire from moving in either direction on the shaft of the bit. Your post reminded me of it.
Simple, but works !

[johnny means]

You could simply center the bit in the v-block.

[Myk Rian]

You could simply center the bit in the v-block.
That's too easy.

[Mike Heidrick]

I am more interested to know why you are drilling your rails?

[HANK METZ]

I am more interested to know why you are drilling your rails?

Johnny,
The method also allows the use of a common rectangular drill press vise, hand screw, or simply wedging the round work between two parallels to hold it fast while finding and boring T.D.C.

Mike, the original plans called for a somewhat complicated method of strapping to secure the rails to the base ends, calling for tedious adjustments to get decent parallelism. By simplifying the mounting, final adjustment was a quick and easy process that just needed a few paper shims and now I have a rail system that will probably hold true over the life of the build;


1st step was to brad nail front and back boards together and saw a “V” groove, ensuring perfect spacing:
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Next was to install the aforementioned rails with a single countersunk screw at each end:

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I can now remove and replace the rails with no further need to recalibrate all over again.