I've been picking up more eBay and Harbor Freight stuff lately, as I segue into retirement. I feel like a squirrel getting ready for winter. I don't want to run out of tools before I die and I'm afraid I won't be able to afford them after I retire.
I ordered a pair of these 6" digital calipers for $15.99 from the Harbor Freight website, figuring I couldn't go too far wrong for that price. I received them in the mail today and eagerly opened the package. Disappointment.
They powered up but the LCD was reading random digits, unrelated to the slide movement. I changed the battery (they come with a spare) but that made no difference. I removed the battery for 30 seconds to "reset the circuit" as recommended by the manual. No change.
Just before I pitched them into the trash, I became curious. They must have been designed to function - how hard could it be to fix them? I peeled off the label covering the screws on the back and ignoring the warning label, "Do not disassemble the Dial Caliper," I tore into them.
There wasn't much inside, just a "reader" board inside the plastic shell. I noticed two pieces of plastic tape between the plastic shell and the metal frame of the slide. It appeared to be a rudimentary shim, but I reasoned it might be elevating the reader from the scale far enough that it wasn't able to "read" it (also, the stationary scale is black on dark blue background which might also make it difficult).
I removed the questionable "shim tape" and reassembled the calipers, inserted the battery, and they worked perfectly. These are actually a pretty fair knock-off of the Mitutoyo digital caliper. They have a thumb wheel, metric/inch reading, zero button, and auto on/off. I'll check them tomorrow with my gauge blocks and see how accurate they are but so far they look pretty good and they feel just as smooth as my old Mitutoyo dial caliper.