Dial Caliper

[custard]

I just got a new metric dial caliper to replace my old vernier imperial caliper, I can't recall the name but it's a decent brand. It arrived with no instructions and when I close it the dial reads about 0.04mm rather than zero.

Couple of questions,

1. Is it a pup?
2. If not, how to adjust?
3. Underneath the dial there's a knob, but the function isn't immediately apparent, any suggestions?

Thanks

 

[OLD]

The knob could be a lock as you usually move the scale to bring the reading to zero (rotate the housing)then fix with lock knob

 

[custard]

Thanks Old, that's sorted it!

Incidentally, I like the look of the garden bench in your avatar. Are plans available for it?

 

[OLD]

Its a childs bench plans provided by this forum.
http://www.stapeley1.plus.com/childs bench Adjusted.jpg