How to align 2 parts that lock together

I have managed to align parts by there centerline

now I want to align these 2 parts by there center line axis.
then rotate these 2 parts together.
not sure what to do next.

I’d use the Orient command for this. It lets you select two reference points which would be center points on each end of the part that looks like an ear plug and then two target points along the axis of the bent wire.

Post your file if you need more help.

I couldn’t find the center of the hook"
I found the center of the colar but no point to choose on the hook
hook colar.3dm (508.4 KB)

Hi Kevin - if you TweenCurves the two opposite edges you can get a pretty good centerline:



Thanks, I got that to work!, now if I can remember what I did.
I had just about gave up

Screenshot (252)


i spoke too soon, it didn’t work
hook colar.3dm (541.4 KB)

Hi Kevin - is this more or less what you are shooting for?
hook colar_maybe3dm.3dm (814.6 KB)


this is what I was trying to do.
I used rotate but was trying to snap to centelrine

Yes, sorry, I meant the general construction of the wire object - yours seemed ‘approximate’ and I was curious if the goal was something more exact, which would make alignment easier.

Here it is, aligned -

hook colar_maybe3dm.3dm (440.1 KB)


I was looking for exact, the 1st time I tried I thought it worked but now I can’t get it to work. I can see your example is lined up both axis of both parts, that is what I was wanting to do. I will just have to try some more. thanks for your help.

Hi Kevin - if you look at the centerline in my file you’ll see that the straight bits are actually straight lines, the big arc is a true arc - etc. If the design is meant to have specific geometry, it usually pays to draw it that way - then, for instance, matching the second part up to the centerline with Orient becomes a more precise operation.