Starrett Indicator Repair
My Dad gave me this nice old Starrett indicator a while back which wouldn't repeat 0 very well. Have been wanting to put it to use so took it apart to give it a clean and find anything else which could be wrong.
Sorry for the lack of disassembly pictures but it's fairly straightforward. Unscrew the plunger button from the back and carefully pry the glass/bezel off with a screwdriver. There will be a circlip type of ring holding the dial mechanics into the case. The circlip has four tabs which fit into slots in the case. Squeeze the tabs out of the slots and remove the circlip.
Under the dial will be two sets of brass shim washers (sorry again for lack of photos). The first will have a slot in it so this washer can be slid out around the gauge's leadscrew (correct term?). The other brass shim is a wavy spring washer which creates pressure against the back of the dial face, leave that one there.
Maneuver the dial face and spring washer and you will see two screws which connect the dial to the bottom of the case. Remove these two screws and remove the face. Carefully remove the brass spring shim washer.
The front and back of the dial will now be in two parts.
This is a close up of the bottom case. Notice the plunger which is the shaft in the middle and the spring which returns the plunger to its start position. Also notice the little post which comes out perpendicularly from the plunger and the locator holes in the bottom of the case. Notice the two notches in the rim of the case, this where the dial locates and screws into. You can see the two brass washers and circlip in the blurry background.
This is a close up of the back of the dial. Notice the leadscrew, at the end of the leadscrew is a point which seats into the locater hole in the dial base. Also notice the small coil spring, this is used to tension the dial and is the thing which allows it to repeat 0 correctly. If this spring is not tight when the dial is assembled it will not repeat. Notice the strip of metal everything is mounted to, there are screw holes at either end of the strip (finger is covering one up). You can see notches in the strip around the screwhole which fit into the corresponding notches in the case.
I gave the mechanism a good clean out as there was noticeable stickiness in the plunger movement. Then I wound up the watch spring while holding the needle so it would not unwind. A folded up piece of paper carefully wedged between the needle and dial face can be helpful here to hold the needle in place as outward pressure on the needle is necessary.
Remember to put your brass spring washer behind the dial now. Situate the dial leadscrew and little post on the plunger so that the two will mesh easily. If they are not close to the right spot you might end up trying to force the dial back into the base and bend something. You're actually trying to align three things when putting the dial back together. The pointy end of the leadscrew into the locator hole in the base, the plunger post into the leadscrew and the dial face notches into the notches in the case. All while trying to keep outward tension on the needle. After a bit of fiddling hopefully it locates and you can return the two small screws which hold the dial into the case. Add your slotted brass washer now on top of the spring washer. Push the assembly down into the case and fit the circlip on top of the face.
Test the indicator and if everything is working properly return the glass bezel. Looks like someone had broken the glass in this dial and replaced it with some gunky plastic. Will try to fix that someday.
Hope this is helpful if anyone has any "shot" indicators around.
