Problem with constrain tool and offset from plane

[Anonymous]

I am having students use the offset from plane tool to make holes in the sides of cylinders. The holes are placed completely through the cylinder (rounded sides).  When my students try to use the constrain tool (insert button) the holes in the cylinder will not highlight to place a peg into it.  If I barely make the holes touch the side of the cylinder, I cna insert the pole into the hole.  What am I doing wrong that the holes will not highlight?

I can use the mate tool in constrain, but that allows the pole to keep moving.

[mrattray]

Is it really a problem if the poles can rotate? If not, then I would just leave it be. If they have something coming off of them or whatever, then I would add a second angular constraint to one of the origin planes, or otherwise constrain some other part of the pole.
I may be lying because I don't use it much, but I believe that the insert tool will only accept circular edges as input. A hole through a cylinder is a 3 dimensional spline, even though it will look like a circle when viewed along its axis.

[graemev · Accepted solution]

The insert constraint needs a circle or arc to attach to.  A circular cut through the cylindrical surface of the pole does not generate either.  For "peg through side of pole" like I suspect you're doing, you'll need to Mate the axes and either Tangent the face to the cylindrical surface or Mate an end (or origin plane/axis/point) to the pole's axis.  Which you choose to use would depend on the design intent, I suppose.