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When working on projects, proper measurement can be one of the most enigmatic and frustrating skills to master. Mistakes can be time-consuming and costly, especially when removing material. Makers often learn the hard way how to measure properly. As they say, good judgement comes from experience, and experience comes from bad judgement.

Here are some helpful pointers to make sure you measure correctly, and use the right tool for the job.

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Michael Colombo

In addition to being an online editor for MAKE Magazine, Michael Colombo works in fabrication, electronics, sound design, music production and performance (Yes. All that.) In the past he has also been a childrens’ educator and entertainer, and holds a Masters degree from NYU’s Interactive Telecommunications Program.


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Comments

  1. trkemp says:

    “Stick to one tape measure to keep your measurements accurate.” I think you mean to keep your measurements consistent. It’s hard to know if a particular tape measure is more accurate that another without a proper calibration standard, but by using a single reference your measurements will be consistent.

    It’s the same principle as using a single reference model when duplicating a lot of pieces. It’s usually not so important that the copies be an exact size as that they all be the same size.

  2. Dave says:

    For a ruler for the workbench, saw table, etc., if you’re lucky enough to have an IKEA store near by, grab a few of the paper & vinyl give-aways they have in the furniture section. I’ve found them to be accurate, and they can easily be stuck down and evn overcoated for durability.

  3. caitlinsdad says:

    Sometimes the most accurate measurement is not to measure at all. If transferring measurements, just place side by side to tick off or use a story stick. Learn how to bisect angles or find centerlines by drawing diagonals. All of those geometry proofs you learned in high school that you thought were useless can be applied in creating parallel lines, angles, and figuring out measurements. A sharp pencil, knowing where to cut on your line, a pair of dividers all add to the precision of what you want to do.

  4. terrefirma says:

    And most important…practice. If you want to be a maker, you gotta keep making!

  5. Alan S. Blue says:

    I don’t think there should be any slop at all in the butt of a tape measure. And I wouldn’t use cloth tape for anything but clothing-type crafts.

    I’ll second the idea that ‘transferring the measurement’ can be mighty useful, which brings up an entirely different set of measuring tools. Outer calipers, inner calipers, or just a good two-point compass or ‘divider’.

    Using exactly the same measuring widget is slightly preferred … but what you actually want to be doing is checking incoming instruments and chucking or fixing the defective ones. This is kind of the entire point of NIST and standardizing in the first place. Just because your widgets all assemble when your (defective) measuring device is used doesn’t mean it’s going to (a) work properly, (b) pass inspection, (c) fit into the larger device, (d) avoid lawsuits.

    Measuring Tricks

    1. chuck says:

      The slop in the hook end of a tape measure is to compensate for the thickness of the hook edge when hooking over the end of what you are measuring or butting up to it. Imagine measuring a table top and then measuring the inside dimension of a box. If it doesn’t move slightly, your measurements will be off.

  6. David says:

    “Measure twice. Cut once.”
    Not all factory edges are true especially plywood edges and lumber ends.
    Knife tip or needle-as-scribe gives a very fine mark.
    To mark smooth surfaces like metal, ink the area with a felt-tip, then scribe.
    Broken metal tape measures can be used for short lengths; bend sharp at whatever foot mark to break.

  7. Nicholas says:

    And the little tip of metal sticking out the “other” end of (digital) calipers? The depth gauge.

  8. Ian Bullock says:

    If you’re doing CAD or shopping for parts, it’s great to have a ruler and calipers within arm’s reach at your desk. I keep my ruler in a slot on top of my monitor, and calipers on the monitor stand.

    If you’re buying cheap calipers (~$20), I actually prefer analog – the batteries don’t die, and you don’t have to keep re-zeroing all the time. (Nicer digital calipers may not have either of these problems, though.)

  9. Max Corrigan says:

    Being a bit pedantic in the UK a “ruler” is used in schools and offices, in an engineering environment where i was employed for more than fifty years, it was referred to simply as a “rule” if you asked for a “ruler” you would get strange looks!
    Never the less a good article, keep em coming!
    Maxc London

  10. A handy tip if you need to cut at for instance 123cm and you only a one meter long measuring stick, mark at 23cm from start, then add the meter and mark the cut, this way it is more obvious that you are about to cut at the wrong mark :)

  11. Georgia3 says:

    I cut it 3 times and it’s still too short….

  12. Bryan says:

    If your tape or scale (rule/r) is banged up, use the first major mark as the new “zero” (e.g., measure 6″ by spanning from the 1″ mark to the 7″ marks). Just be sure to subtract whatever that mark was from the overall measurement. The ends of a tape or scale often get dinged up, and on some models the original zero was actually a mark instead of the physical edge, and the leading marks somehow tend to wear away quicker than the rest in my experience.

  13. BC says:

    Can anyone give me tips on how to make inside measurements? Example: measuring the distance from side-wall to side-wall inside a cupboard. I find it tricky to find the measurement where I’ve bent the tape to fit it inside the cupboard. Am I doing something wrong? Are tape measures a standard size? Or do people just measure their tape measure, rest the tape measure against the side-wall, and add the length of the tape measure to the length shown by the tape?

    I have a feeling I’m being an idiot here and missed this basic thing in shop class.

    -BC

    1. Nicholas says:

      I always assumed you added the length of the tape measure. Mine is clearly labeled on the side as to being 3″.

      1. BC says:

        Great. Thanks. I’ll see how long my measuring tape is. If it’s not a whole number (like 3″) then I’ll buy one that is.

    2. trkemp says:

      If you want a little more accuracy, measure from both sides to a point between. For example, if you are measuring a cupboard, measure from one side and make a pencil mark. Then measure from the other side to the mark and add the distances together.

      1. BC says:

        Thanks trkemp. That’s a good tip. I didn’t think of that.

    3. fotoflojoe says:

      A simplified version of trkemp’s idea: Cut a small block to a known size, say 6in/15cm. Place the block tight against one inside corner, and make a small tick mark. Measure from the opposite corner to that tick mark. Add 6in/15cm to your measurement. Mark the size on the block and keep it in your toolbox, alongside your tape measure.

      1. David says:

        Inside Measure:
        Two square / rectangular sticks each longer than half-way. Working ends should be “pointy” for easier removal of assembly. Place pointy working ends at sides of cabinet, overlap sticks in middle. Clamp overlap. Remove clamped sticks and measure overall length.
        Or: “Inside Dividers”. Make-your-own big enough..

  14. BC says:

    I feel like this should be built into tape measures:

    http://www.leevalley.com/en/wood/page.aspx?p=70093&cat=1,43513