Introduction: Cross Hole Drilling in Round Rod Stock

Picture of Cross Hole Drilling in Round Rod Stock

Repeatedly bore accurate holes through metal, wood, plastics or other round shapes with this simple method and a drill press. The principal is quite straightforward; easily find the top dead center (T.D.C.) of a round rod, usually a difficult task without specialized tooling. This tip readily 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. To clearly demonstrate the principal I used a shop made "V" block which would suffice by itself for this task.

Step 1: How to Setup

Picture of How to Setup

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 against the setup and observe the flat for parallelism to the fixture.

Step 2: Finding T.D.C.

Picture of Finding T.D.C.

Adjust work and fence to make the flat parallel, thus top dead center is found. To complete, spot drill, bore to desired diameter, repeat as described below if needed.

Step 3: How to Do Serial Drilling

Picture of How to Do Serial Drilling

Fasten a deadweight- I used a handscrew- through a previous bore, let free hang to ensure a vertical lineup of sequential holes for boring.

Step 4: Why Do This?

Picture of Why Do This?

Cross drilling the end of a shaft is commonly used for economically retaining bearings, wheels, spacers, etc with cotter pins. A more demanding use is to insert a roll or dowel pin to transfer rotary motion such as driving a wheel, engaging a clutch, cam, or other mechanical connection.

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Comments

pfred2 (author)2014-08-19

What you call a "centering tool" I call a spud, which is vaguely related to a bull pin although it should never be confused with a bull pen!

technovative (author)2014-08-19

I like these techniques. Thanks for sharing. A thought, a small bubble level such as a torpedo level could be used as the indicator. Then you'd have a dual calibration gauge. Adjust until the straight edge looks parallel to the top of the v-block, then check the bubble for fine tuning.

The legendary Starrett Tool Co. made a highly precise bubble level for accurate installation of metalworking lathes that must maintain super low tolerances. A good thought, building on a sound idea never hurts and thanks for submitting this.

seamster (author)2014-08-19

Excellent tip. This is something I will definitely use in future projects. Thank you for sharing this!

rimar2000 (author)2014-08-18

I do this often.

I do first a flat shallow groove with the grinder in the desired site. After that, is relatively easy to drill the rod / tube. If the centering of the hole is important (not always it is so) you must be careful seeing the drill bit from the end of the piece to keep it in position.

BeachsideHank (author)rimar20002014-08-18

Grinding or filing a flat is a very good way to prevent a drill bit
from skating about the apex of a round. This method gets you inline with true
center simply and very quickly.

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