Starrett 120A-6 dial calipers
This is the dial caliper to buy if you love "made in USA" tools and are thinking of keeping jobs at home.
You would think that Starrett could supply a suitable photo of this dial caliper. This is unfortunately the only image available at this time. We will work on getting a better shot.
Starrett Dial Caliper Features
(Rather fanciful product description provided by the manufacturer. You are welcome to ignore any or all of this mumbo-jumbo.)
The Starrett dial caliper has sharp black graduations every 0.100" on the no-glare, satin-finished stainless steel bar, and graduations on the dial every 0.001". One full revolution of the dial is equivalent to 0.100".
These calipers have knife-edge contacts for measuring both inside dimensions (ID) and outside dimensions (OD). The knife-edge contacts can be used to scribe parallel lines on the workpiece.
This caliper can be used with one hand by operating the fine adjustment roll with the thumb.
The lock screw locks the dial bezel and holds the sliding jaw in position.
The depth rod is integrated into the rack of the caliper, unlike many calipers which offer a detachable depth rod, or none at all.(*)
"The hardened stainless steel components, including the bar, measuring surfaces, rack, gears, and depth rod, offer corrosion resistance, increased accuracy, and long life. Positive split gear anti-backlash control offers increased accuracy over standard gear configurations. Backlash is the amount of clearance between mated gear teeth in the caliper controls, which prevents the gear teeth from jamming. It is undesirable to have much backlash due to the lack of precision offered by the increased amount of play between gears. Certain gear designs can minimize or eliminate backlash; split gear systems actually split the gear into two gears, each half as thick as the original gear. One of these gears is then fixed to the shaft while the other gear is allowed to turn. The free-turning gear is connected to coil springs that rotate it until all of the backlash in the control system has been eliminated. The rack teeth point down to keep foreign matter from clogging the gear operations. This prevents measurement errors where metal chips could interfere with proper caliper operation."
(*) This sentence makes no sense to us. All calipers come with depth rods. The Starrett depth rod is not "integrated into the rack". How could that work? [Editor's note.]
Note: Model 120A is an older, discontinued version of this current caliper. Some repair parts will be different and may in fact be obsolete. There are also Starrett dial calipers which are made in China. They have different part numbers and the much lower price will give them away. If you want to be sure to get the real American made calipers then insist on model 120A-6 (for the 6" version).
Additional information on dial calipers
Zero setting the Starrett dial caliper
If the hand is no longer set on zero then the gear jumped a tooth because the gage was dropped or hit. It doesn't necessarily mean that there's internal damage. If the caliper still moves smoothly then everything's probably okay. Resetting the hand is a bit tricky but it can be done. Remove the bezel clamp and then tilt the bezel off carefully like the plastic lid on a take-out cup of coffee. (Pretend the coffee's hot.) The hand can then be pried off using a hand lifter or two smallish screwdrivers, one on either side of the pinion. Do this with caution so that you don't break the center pinion in the process. Now realign the hand to zero and tap it back on, gently but securely. Reassemble and you're all set. Don't attempt to play with the movement or to remove it. The gears are preloaded and you'll have a heck-of-a-time trying to get things to work again. If you're squeamish about all of this, send the gage to a repair shop (we no longer repair Starrett calipers). For additional instructions on dial caliper repair, refer to page 44.