Protractor calibration

[Hitch]

I have a vernier style protractor. Got dropped hard yesterday, and now its just over half a degree out. I'd like to have it right again.

Taken the top off, and it reveals 4 small screws, i have tried looseing them, and rotating the measuring ring, but it just goes back to being half a degree out.

I notice there is two 'pads' where the rule part seats against the body....should i be trying to use them to calibrate it? Can't see any adjustment though, without knocking them in, or filing one back a bit.

 

[zxr400]

Under risk of stating the obvious, I would have said that the outer ring would have to move independently of the inner ring to carry out adjustment.

The pads sound like a form of support, rather than a means of adjustment.

It's hard to see the detail from a piccy, but one thought would be to try and loosen off the centre bezel, and see if it is somehow clamping down the outer scale to the inner hub?

Can you post a detail shot of what you have?

Hope this helps,

Cheers,

Mark

 

[Hitch]

Ill have to bring it home next time im in work to get a shot.

 

[graffian]

On mine the vernier scale is held on with 2 screws and you can loosen it and move it maybe half a degree, I set the protractor to 90º with a block then if the protractor is out I loosen the vernier scale and move it.

Mine is an old M+W looks just like the picture, except it's not pretty and doesn't have a magnifier;-)
Look at the vernier scale I think you will find it is screwed on.

 

[Hitch]

yes, the vernier scale is screwed on, with 4 screws, but they are countersunk iirc, so everytime i move it, then re tighten the screws it moves back again.

 

[Welderpaul]

Can the csk screws be swapped for round heads?

 

[graffian]

drop it again.

 

[brightspark]

drop it again.

:laughing if all else fails :clamp it and give it a gentle tap