Having trouble rigging a drafting compass

Hi Everyone

First time posting here. I’m having some trouble rigging a drafting compass.
Basically, I’d like to be able to rotate the whole compass without any of the
other parts screwing up. I’d also like to be able to rotate the legs open and
close while rotating the whole compass. The wheel and black parts next to
it should move up and down as the legs open close without screwing up it’s
own rotation or position.

I’ve tried a few things with constraints, but so far every time I use constraints,
something, like position, messes up. Or when rotating the whole compass, the
legs rotate at a slower speed. I suspect I’m doing something wrong.

Any help with this would be greatly appreciated.

Attachments

compass.blend (2.77 MB)

Welcome to BA!

Me, I would do it with an armature:


Blend file: compass.blend (2.58 MB)

Just press Play - I have added some keyframes to animate it. :slight_smile:

The values in the Transform constraint for the screw bone are approximate to get it to look right, you may tinker with this…

Cheers, Clock.

Here’s one way to get the compass parts to rotate around while drawing a Circle…
not sure if that’s what you are wanting…

Set a Root bone as the Base of the point for the whole compass to rotate around then build from there…

like this…

compass_NorvMod_001.blend (2.86 MB)

set copy rotation constraints and set the spaces to ‘local’ the Leg.L will need to be set to copy rotation in ‘invert’ mode…

you should be able to parent the adjustment screw parts to the center ‘assembly’ bone and use the info that clockmender is showing you in his example…

Thank you very much to both of you. I have it sorted now and learned something new :smiley: