Cross Hole Drilling in Round Rod Stock




About: Was it you or I who stumbled first? It does not matter, the one of us who soonest finds the strength to rise must help the other. - Vera Nazarian, The Perpetual Calendar of Inspiration

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.

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Step 1: 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.

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

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?

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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    6 Discussions


    5 years ago on Introduction

    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!


    5 years ago on Introduction

    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.

    1 reply

    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.


    5 years ago on Introduction

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


    5 years ago on Introduction

    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.

    1 reply

    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.