Help needed with understanding accuracy in measuring tools. I want to go straight :-)

[Boyan Silyavski]

Thanks for the info. They would ship it together with flat wood piece for protection, i believe.

You were right. I get what i pay for :-)

The Igaging digital protractors came. Hughghghgh. Checked against my new supersquares and even against my ordinary squares, when zeroed on flatish surface and then measured 90 degrees, they show 89.75 or 90.25, depends if you take the measures from inside or outside. Ha ha ha. for 11 euros each, that's all folks. However i played around with them and noticed that the electronics and the dro discs are extremely accurate. The problem comes because they did not drill the axle hole on the right place.

I thought of throwing them to the bin. Then decided to think deeper. Measured the plates, each is perfect. Then what? Opened them to 180 degrees so both corners touch a flat plane. Zeroed. Closed so again both corners touch a flat plane. Spot on 180 degrees.

So, i invented a cure. Open them flat to 180 degrees until they are dead flat. Zero. Close them untill shows 180. One edge is not at the same plane compared to the other. Scrape it and repeat until they are spot on. In other words file untill the bolt is where it should be- at the center.


PS. I couldn't do it. At least for educational purpose opened it to see whats making it tick. Now i get it. Wasnt the problem in the steel axle hole placement. Encoder disc attached to the axle which enters a cavity, like a bearing entering its place. So , plastic in plastic. That means the screws and the plastic construction of the device is the problem. The encoder disc not being in perfect center makes the problem. And as its not a tight fit, it could never be centered.
Bottom line: You get what you pay for