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Thread: How to Measure Engraving Depth

  1. #1

    How to Measure Engraving Depth

    When you get a spec from a customer specifying a depth to the engraving is there a tool or technique that can be used to measure accurately? I have a micrometer with a pretty small anvil but itís not small enough to fit into the characters.

    Any help would be appreciated.

  2. #2
    Join Date
    Dec 2012
    Bedford, NH
    How close must your depth measurement be?

    Is your micrometer similar to this style!537572250427! ?

    Do you have a dial drop indicator, or similar, that you could use? Or, could you use the micrometer with a fine point pin to measure to overall dimension (pin length & groove depth) & then subtract the length of the pin.
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  3. #3
    Join Date
    Aug 2006
    Suwanee, GA
    Over the years I received various RFQ's that included a specific depth for engraving. 100% of the time when I questioned them about it they said don't worry about it, just some engineer that overthought things. Whenever a random customer asked for a specific depth their reply to "why" was always "I don't know, it just sounded about right". In 14 years the only thing I engraved that truly needed a specific depth was serial numbers on firearms and that was .003" - but even then the local ATF agent said their "official measurement" is their fingernail - if it catches on the mark then it's deep enough...

    Bottom line - ask they why they need it and you are likely to find out that it's not that critical and they will likely take whatever you provide.

    Quote Originally Posted by Chris Thomason View Post
    When you get a spec from a customer specifying a depth to the engraving is there a tool or technique that can be used to measure accurately? I have a micrometer with a pretty small anvil but itís not small enough to fit into the characters.

    Any help would be appreciated.
    I have done so much with so little for so long, that I can do almost anything with practically nothing...

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  4. #4
    Thanks Gary. Good advice. I’m quite certain the specs are from an overzealous engineer 40 years ago and no one has bothered to change them.

    I think it would also be a good thing to be able to have accurate measurements just for my own QAQC as well as optimizing engraving settings on the fiber.

  5. #5
    Over the years I've probably called engineers over 1000 times to explain that .020" is WAAYYYY too deep for 1/8" high characters. Nearly always it's just a number the engineer thought sounded good.

    There are good reasons for depth callouts, main reasons are to show up on injection molded parts, and to hold paint, but we've never needed more than .006-.008" deep for painting, and injection molds I typically engrave .008" to .012" deep. One of my long-term customers hold me to whatever they call out because it's what THEIR customer called out, and if they get NCR'd, then I'd get NCR'd. So unless the depth callouts are ridiculous, I conform

    There's an easy way to visually measure depth, but you need to make yourself one of these:
    --if you have a tool engraver, it's easy, and accurate using a depth gauge while engraving the thing. The letters on my gauge are 3/16" / 4.77mm tall, and all engraving was done with the same tool (good eyes will notice I had a loose stepper coupler when I made this ) -As you can see, by .020" the engraving is much deeper than necessary, and at .030" is ludicrous deep.

    If you're using only a fiber laser, then do the same thing, but instead I suggest just engrave "TESTING" or some other word rather than the actual depth (yet). followed by a cut out circle or square that's just big enough for your caliper's or dial micrometer's depth post to fit into so you can measure the actual depth. With a fiber you'll need to keep running and testing until you're at or close to the depth you're going for. Once you're there, now engrave the actual depth to the right of the circle/square. Then move to the next line, repeat... With a fiber you'll want to just work in .003 increments to about .015" deep- unless you're more adept than I am at getting deeper than that!

    That's Part one of your depth gauge 'tool'...

    This is Part 2: Silly Putty!
    Carefully push it into the engraving and you'll get a reasonably accurate 'mold' of the engraving, like this:
    This wasn't a great 'push' as the bottoms of some of the numbers didn't fill in well, but it's plenty good enough to see that the engraving is around .010"-.012" deep, and will show up quite nicely in the rubber seal that mold is going to eventually make. So to measure the depth accurately, you take a second piece of silly putty and press it into the appropriate numbers on your gauge plate, then simply compare the two putty molds using a magnifying glass. It's quite accurate, .003" is quite a noticeable difference under magnification

    In really, just showing the customer a silly putty impression so they can see the actual engraving depth is *usually* sufficient, especially for the guys wanting to make sure it's deep enough that Cerakoting and other coatings don't fill the engraving on their firearms. Great visual aid for YOU too, for that matter - but a plate with known engraving depths is nice to have around...
    Last edited by Kev Williams; 08-16-2019 at 4:07 PM.
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  6. #6
    Mitutoyo 7210 with needle point works really well, just make sure the burr on engraving edge isn’t throwing off the measurement.

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