I've come across this:-

enter image description here

from https://www.amazon.co.uk/dp/B08WXFDRBX/.

It says it's is for woodworking, but the vernier is marked into 2' segments. That seems a little too accurate for wood, and of course the description could very well be wrong. I could envisage this in a machinist's shop. And the associated photos suggest an engineering use, not carpentry.

So what's it do and how could it be used..?

  • 1
    $\begingroup$ works like a micrometer ... it measures the angle of the wedge shaped opening at bottom right ... right now it is showing an angle of 3 degrees 6 minutes $\endgroup$
    – jsotola
    Commented Jan 13, 2022 at 18:07
  • 1
    $\begingroup$ Def. looks like a machinist's tool. Looks like a sort of vernier protractor, with the addition of the adjustable offset, which allows precise measurements of "trapezoidal" shapes $\endgroup$
    – Pete W
    Commented Jan 13, 2022 at 20:33

1 Answer 1


I've never seen one but it looks fairly intuitive.

enter image description here

Figure 1.

  1. The base.
  2. Vertical adjust thumb screw. Release to move the measuring arc away from the base edge to accommodate the thickness of the article to be measured.
  3. Angle adjust thumb screw. Release to allow adjustment of the arc to accommodate the slope of the item being measured.
  4. The zero mark gives the whole number of degrees.
  5. The Vernier scale gives the number of minutes. See Figure 2.
  6. Horizontal adjustment if the base needs to be retracted.

enter image description here

Figure 2. Reading the Vernier scale.

  1. The zero line on the Vernier is indicating a reading of just over 3°.
  2. The closest alignment between the main arc degrees scale and the Vernier minute scale is at 6'.

The readout is 3° 6'.

  • $\begingroup$ Thanks, but I know what the bits are ;-) I'm wondering though how it could be used, especially given the x and y offset legs. And of course part 6 fouls part 1 so you can't stand it on anything, thus you can only measure external angles. Also a resolution of 0.033 degrees seems too accurate for bits of wood. $\endgroup$
    – Paul Uszak
    Commented Jan 14, 2022 at 14:23
  • $\begingroup$ @PaulUszak What about setting up machines for wood? And not the wood itself? And excessive resolution isn't really an issue for woodworking tools if it's easy to accomplish. Like calipers that easily read 0.001" when no woodworker ever works that. $\endgroup$
    – DKNguyen
    Commented Jan 14, 2022 at 21:20

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