[XL650 Owner]

I have been calibrating calipers for several years working with all brands and styles and yes, if its a dial then it has a track with a pinion and spring loaded back lash gear and digital that use and encoder and an inductive track located behind the graduation scale. All calipers have gib screws to adjust out any slop in the slide. They are normally located on the top and at each end of the slide. They press against a brass plate which in turn presses against the frame. have these as tight as you can, and still be able to slide the read head back and forth. Too tight and it wont move, too loose and you get variations in your readings. The most common I see are the Mitutoyo Digital, then their dial version. Starrett is another good one but I don't see as many of those. After that come Fowler which is an import from china and from there all the others. Harbor Freight sells some of the cheapest and least expensive. That's not to say they don't work. They aren't in the same class as the Mitutoyo's or Starrett's, though clearly here, you get what you pay for. All dials have a graduation of .001 and almost all digitals have a graduation of .0005. Vernier calipers or either .001 or .0001. They only have a scale but no display or dial and are the hardest to read for for those not familiar to them. (I would think). For those looking at buying a first caliper get what you feel most comfortable with. Digitals are easier to read than dial and dial are easier than vernier. Just stay away from an all plastic framed caliper, they are worthless. .... my two cents....