Re: Good Calipers?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: The Shottist</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lumpy grits</div><div class="ubbcode-body">I'm old school and use dial type.
Won't own a digital.....to many problems with'em. </div></div>
The digital is accurate to .0005
Dials are accurate to .001
The magnetic media is permanently embedded in epoxy.
Digital allows re-zero at any point.
The digital units don't jump when going from zero to 4.xxx when there is a spec of debris in the rack and pinion because there is no rack and pinion. That was always my pet peeve with my Starret dial caliper. I just ordered the Mitutoyo from Amazon (best prices and free shipping) and am looking forward to retiring my dial caliper. </div></div>
Calipers are rulers with a speedometer.
If your thinking it'll actually qualify a dimension 4 places to the right of the decimal I encourage you to go look at any metrology laboratory in the US or any ISO certified job shop. I'll bet my FFL you won't find machinists or QC techs using a caliper for anything less than +/- .005" on a print. The shops that I worked in wouldn't even allow a set on the work bench in most cases. If it were the case why would anyone (like me) drop 1800 bucks on a full set of Mitutoyo micrometers or $7500 bucks for a Brown/Sharp Digital Height Stand? let alone inside mics, pin gauges, etc.
Use any cliper (and I mean ANY) longer than a month and you'll likely need to calibrate. Wipe off the blades, clam them together, and hold up to a light source. If you see a ribbon of light between the two they aren't right. ANY LIGHT means they are junk. Drop them once on anything harder than the pillow you rest your head on and they should go to one of two places: the trash can or to a service center.
A healthy human eye has about a 2 micron resolution. So if you see light that means they are at least that far out of calibration/parallelism. Rotating the dial to zero or hitting the reset button in an effort to compensate is only fooling the person using them. This is because the dimensioning will vary depending on the amount of pressure used on the thumb wheel and by the location along the blades that makes contact with the part. (since they aren't parallel your introducing a sine error)
Digital anything that depends on a battery for a power source has no business in a shop IMO. 12 years ago I used a set that had a low battery condition. The low battery indicator failed and as a result about $3500 worth of material was scrapped at the saw before the job even made it to the 1st op.
Calipers are very handy tools and I own several pairs of good ones, just don't fool yourself into thinking they are more than what they really are.
Good luck.
C </div></div>
Beat me to it. Thank you! It always makes me chuckle when someone tells me that calipers are accurate to x.xxxx" because the display said so. If it really was true then there would be no reason for micrometers or optical comparators or the litany of other methods for making true 4+ decimal place precise measurements.
Well said