# Today's small project-fix my Starrett 120A-6 dial caliper



## John Conroy (Mar 11, 2021)

I've had this caliper for over 20 years and a while back it skipped the pinion gear over the rack due to some chips. I took it apart to clean it but after re-assembly it was inconsistent in returning to 0 so I put it aside and used a KBC house brand dial caliper which works just fine. Today I decided to have another go at the Starrett but I was nervous prying the dial needle off last time so I ordered a watch hand puller on Amazon. I didn't take any pictures of the process but I found that this model caliper has a split anti-backlash gear driven by the main pinion with a spring that forces the 2 halves of the split gear to spread . Last time I didn't realize that and the spring was out of position between the 2 gear halves. I found out about the split gear system on this model by watching an Abom79 video. He never takes it apart but does mention it. It was pretty simple to pry off the cover and pop the needle off with the new puller then remove the 2 screws that hold the bridge and case in place. I couldn't find information anywhere telling how much to turn the front half of the split gear in relation to the rear so I guessed at 1/4 turn. That was the fix it needed,  removing that little bit of backlash was the answer. Now I can go back to using my favorite caliper.


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## ShawnR (Mar 11, 2021)

Nice work John. I have a Dial indicator on which the dial does not turn to align zero. I have been wondering about tackling it, but it is useful now, albeit not ideal. I don't want to ruin that. Maybe one day.


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