Question to machinists about dial calipers.

[VaniB]

I don't use calipers for work, so pardon if this question exposes my ignorance;

For over 25 years I've been using a Mitutoyo 6" dial caliper for reloading. In recent years, I've purchased a couple of Harbor freight $10 dial calipers as inexpensive addtional spares. What puzzles me when comparing the two different dial faces, is that the Mitutoyo was designed to show 1/10 of an inch with the needle making a 180° revolution, traveling only half way around the dial face.......while the Harbor freight needle makes a full 360° trip around the dial to indicate the same 1/10 inch. Especially as my eyes get older, it is much easier for me to read the larger calibration markings and numbers on the Harbor freight caliper's dial face.

Is there a reason for designing the two differently?....or an advantage or disadvantage of the 180° rotation over the 360° to get the same readings?

 

[mks]

I have an old Craftsman that is 180, and a newer Starrett that is 360. I think you have identified the only important difference - 360 is easier to read. Just an improved design that has been widely adopted.

Keith

 

[VaniB]

thanks.

I literally have to use a magnifying glass in conjunction with my reading glasses to read the tiny Mitutoyo tick-marks.

Because of this, I have pretty much retired this caliper to mainly occassional double checking duties. I also find the Mitutoyo is great for double checking which Harbor Freight $10 LED caliper or $10 dial caliper works accurately as its replacement. The truth is, if you initially hand pick a $10 Harbor Freight caliper inside the store before you buy it, it's every bit as accurate as the $150 Mitutoyo.....and I can read the H.F. without using a microscope. LOL

 

[RWO]

Mitutoyo makes dial calipers both ways; either .1 or .2 " per revolution. For my aging eyes, I switched to their digital calipers years ago and never looked back. They have digital caliper technology absolutely perfected and the versatility of incremental or absolute measurement , instant metric conversion, no rack to get dirty, resistance to shock, large display, etc. makes them a no brainer for me.

RWO