Aliexpress measuring tools

[Sonic EscapeParticipant @sonicescape38234]

A few years ago I bought a digital indicator from Aliexpress. Although I have a lot of analog indicators, this one immediately became my favorite. It has the advantage that it measures 25mm and obviously you can set it to 0 anywhere.
Today I thought I would check it together with a Shahe micrometer (also from Aliexpress) and some Soviet gage blocks. And horror! The digital indicator has a constant offset of more than 0.5mm! The battery is new. It seems more like a software bug than a real lack of precision. On the other hand, the Shahe micrometer turned out to be excellent!

……………………………………………….

Half an hour later. I just realized I made a major error. The indicator was not touching the milling table. I raised it a little and forgot to lower it. I discovered it now when I wanted to remove it. This was the cause of the offset. I made again the measurements with the same gauge blocks. The offset is ~ 8 microns over most of the range.

 

[HuubParticipant @huub]

I use the cheap Chinese tools for daily measurements and the expensive Mitutoyo’s only when accuracy is tight. Can’t say the results are far more accurate but just more reliable. The operator error is more likely the largest uncertainty.

[cedric 1Participant @cedric]

The indicator is a comparator tool, not a measuring tool. So it will do just fine for home workshop use.

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