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Precision Marking

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  • Precision Marking

    If I'm not mistaken, 0.5mm is greater than 1/64". Even if it isn't my question still stands.

    For really fine work, how do you mark?

    I'm not yet using a knife, but I did get out the drafting leads and holders and a sharpener.

    Thanks for your thoughts, Curt

  • #2
    1/64 inch is .015625 inches
    0.5 mm is .019685 inches
    1 sheet of office copy paper is roughly .004 inches thick, or 1/256 inch, or 0.1 mm

    Yes, .5 mm is larger than 1/64 inch

    The common feeling is to ignore the measuring tape on a table saw, but I routinely use the tape on my TS3612 to measure to 1/4 of a division on the tape, or to 1/128 inch. To get it calibrated, I measure a completed cut with my digital calipers, and adjust the saw's crosshair to match actual. When using a jig or something else that will throw it off, I cut slightly proud, measure with the digital caliber, then use a chart I made to translate the difference back to fractions I can use to adjust the saw. Since I got the good caliper and started using this technique, my mortise and tenon joints have improved immensely.

    For larger cross-cuts, I use a very sharp pencil, although some use a knife, measuring off the mate rather than off a ruler. In either case, after making the mark, I decide whether the edge of the cut needs to split the mark, take most of the mark but leave a little, etc. These cross cuts are done on the Radial Arm Saw so that I can look at the mark, and adjust, as the blade approaches. (I occasionally use a drafting pencil as you suggest, but when the line is fine enough to use directly, it breaks the grain of the wood just as a knife would - just as the pencil point breaks - so this isn't the ideal solution to me. I mainly use an ordinary #2 pencil, sharpened, and then compensate for where I want to cut on the line)

    For larger rip cuts, I just use the tape to adjust the fence on the table saw. Remember that wood expands and contracts in that axis, so you probably shouldn't be building to extremely tight tolerances in that axis. I have traditionally allowed for 1/8 inch or more expansion/contraction across the grain of the usual 12-20 inch wide piece, but recently saw an article that suggested allowing 3/8 inch per foot.

    My eyes are not good enough to accurately read 1/64 inch on a ruler, so critical dimensions are always taken off the workpiece (such as fitting a moulding) or measured with a caliper (such as a tenon).