Optical Centrepunch Is An Easy Build If You Need One

Tired of getting his centerpunches thereabouts but not quite there, [Uri] decided something had to be done. A common tool to solve this problem is the optical centerpunch, but models on sale were just a little too pricy for something so basic. Instead, [Uri] elected to build his own.

An optical centerpunch is a simple tool that helps machinists hit a centerpunch dead on target, time after time. A guide is used that holds a clear plastic rod with a dot in the center. This dot is lined up over the spot to be centerpunched. The plastic rod is then removed and replaced with the actual punch that does the work. Not content to build something utilitarian, [Uri] instead sculpted the tool into a likeness of Sgt Pepper (of Yellow Submarine fame). Seeing the hunk of bare brass quickly become a recognisable figure on camera is a testament to [Uri’s] skill as a sculptor.

It’s a tool that can be readily built by anyone with a lathe, or, at the very least, a decent drill press. We imagine it would be particularly useful for those without perfect vision, making it easier to get punches on the mark on a regular basis. [Uri] has graced these pages before, too — he previously built an ornate tool to make all the other hammers jealous. Video after the break.

27 thoughts on “Optical Centrepunch Is An Easy Build If You Need One

    1. I have a Skidmore optical center punch and I just never used it, maybe once or twice after I got it. It uses an alinco magnet base to keep it from moving at least when you use it with steel and a magnified eye piece with a reticle at tbe bottom. Someone has the same one here: https://www.youtube.com/watch?v=vXm31SRCGaA

      Honestly they are kind of pointless, high precision center marking for one of the least precise machining operations. Especially since if you are doing this you are probably drilling it by hand or on a drill press.

      I do have a nice Starrett automatic center punch which I use for about everything.

      1. I have an automatic centre punch as well, but a couple years ago I was watching a Youtube video on warbird restoration where this bloke was centrepunching the rivet holes in a large sheet of aluminium held against the side of the aircraft (might have been a B-17 from memory?) before drilling for the Cleco’s.
        The automatic punch he used though, was most intriguing – the point part was held against the metal, the middle was a tension spring. The back was pulled back and let go to form the punch.
        I thought it might have been an old WW2-era tool but after investigating, found it was a thing called a “two bit snapper”.
        My wife got me one for Christmas that year (had to import it from the US, not cheap) and I must say it leaves my traditional automatic centre punch for dead. I love it!

      2. There are still people who do high precision work by starting off with extremely carefully scribed lines that intersect, and do indeed use this to establish accuracy- clock and watchmakers, tool and die makers too. Both me, for example.

        You can actually move a centerpiece prick mark if you’re careful with one of these, but only if its well made.

        Not everything is done with cnc. I made a clock by hand this way, punching over scribed arcs, stepping up drills, and hand reaming to fit.

        These still have plenty use, just not for you.

    1. some brass alloys are partially lead, I imagine that’s what oiegj is going on about. not really a significant issue unless you are heating it past melting point in an enclosed area. Even as a drinking vessel, it wouldn’t a significant issue for an adult, I think.

    2. Gloves are an over-reaction. Brass is mostly copper. Copper itself is somewhat toxic. The green corrosion often seen on brass is copper sulfate. Also somewhat poisonous. Common free-machining brass has around 3% lead in it. Sometimes other metals like arsenic are in the mix. Lead is toxic and causes neurological problems. California (naturally) has restrictions on leaded brass. But, I’ve spent a lifetime up to my armpits in copper, lead, arsenic, and other stuff regarded as toxic. I’ve always lived in houses with copper pipe soldered with lead-based solder. I’m apparently not dead yet and possibly not unreasonably crazy. Wash your hands before you eat. Don’t breathe solder fumes or machining dust. Don’t don’t worry about it. Everything is toxic in sufficient quantity, including water., oxygen, bacon, etc.

      Optical center punches are great. I use mine often. You can get within 5 thousandths without precision machinery. With a little care, your drill bit will cut pretty much exactly on the mark.

      1. Most of what California calls toxic, a human would have to ingest so much of in such a short time to have any effect, it would be physically impossible to achieve. Apparently the State thinks lab mice and rats = humans.

      2. The green patina on brass is basic copper(II) carbonate, Cu2(CO3)(OH)2, and yes, it’s toxic. And gloves are something of an overreaction. Copper metal is pretty much innocuous, the vapor pressure is far below the level that might be considered a problem. Soluble copper compounds are not innocuous…but AFAIK basic copper carbonate is not absorbed through the skin; in fact it’s solubility in water is quite low, on the order of a few parts per million or so. Wash hands after using.

        Brass/bronze doorknobs are great for those who are concerned about COVID19 or other microorganisms. Their lifespan on copper alloys is quite short.

        Username relevant.

  1. I love Uri´s work and his tongue-in-cheek-understatement humour as well as his makeshift approach. He combines a fair amount of skills and aethetics. A gifted person and I am sure meeting him in person would be a very pleasant experience.

  2. I love this man’s work. While obviously intended to be functional, his handmade tools are also beautifully artistic.

    I still have some wood planes belonging to my grandfather, including a few that he made himself. In his day, you couldn’t go down to Home Depot to purchase complex wood moldings, you’d make them yourself. To make them, you needed a suitable plane.

    So, first you’d hand-carve a plane body (from hardwood) that reflected the desired molding profile. Then you’d re-purpose some harden-able steel (like an old file) , grinding it into a blade with that same shape. The blade was affixed to the plane block with a wooden wedge. With the tool finished, you could then plane away at some square stock to make your molding.

    In an age of mass-produced, inferior (and largely disposable) tools from places like China, the idea that a craftsman’s tools are an extension of himself has been largely forgotten/abandoned.

    Bravo, Uri.

  3. It was 20 hacks ago today, that Uris brass man began to take shape, so let me introduce to you today, Uris making punch line fame….

    Love, love the way you punched out that tune.
    This is art…..
    Thank you

  4. The video is a joy to watch and i wish i had the skills to make such a brass figure. I watched a couple of other video’s abut making an optical centerpunch and they make the acrylic part that’s sticking out on top a larger diameter, so it catches more light and you can keep te center dot on the workpiece to get optimal precision.

  5. This is a hyperbolic nanny statement if ever I heard one.

    Yes, 360 has lead added, but so does 12L14 steel, which is extremely common.

    Amalgams in your mouth for fillings use mercury. They are stable and chemically inert because they form an amalgam.

    If you are breathing dust from cutting- not good for you.

    But to just touch brass bare handed?

    There is no danger. You don’t grasp how alloys work.

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