"X" marks the spot for lifting a pyramid roof


So, it seems simple in the instruction. Make a rectangle. Draw an “X” through the center. Select the move tool with nothing on the model selected. Click the center of the X. Hold down “up” arrow to lock up/down axis movement and pull up.

Here’s what actually happens to me often (one of several things).

  1. I am firmly holding the “up” arrow, but movement is not constrained to that axis.
  2. The point doesn’t move and I see a message such as "constrained to intersect plane."
  3. Sometimes I have seen the instruction to move the point a little in the desired axis, then press the UP key, but getting that initial movement in the up axis often doesn’t work and wanders off on another axis, so that there is no point now in constraining it to that axis (the point is no longer centered on the plane).

I don’t get it.


What’s not mentioned as much is how the angle of view influences things. Depending upon how you’ve rotated your model, and from what angle you’ll be working towards – any one of the approaches you’ve outlined might work better than the others.

I typically go with option 3 most of the time, and when it gets a little tricky to find and lock onto an axis, I rotate the model a little bit and try again.

When I really need to work in a constrained way, with tight precision I setup guidelines, and/or relocate the axis position… and that practically guarantees good results.

As far as your description of outcome 1: I don’t see the benefit of holding down on the up arrow key. Pressing it briefly when you’re in the neighborhood of tracking the correct axis will help it lock onto it. But to keep it constrained on that axis while you’re pulling up, so that you can refer to some other point in the drawing, I alway hold down on the ‘SHIFT’ key for that purpose.

Ultimately, it’s a feel thing and you’ll develop a kind of muscle memory for how this works over practice. Timing is also part of it. . . there is a moment when pressing the up arrow key a little too early, or too late, doesn’t work so well.

Also, sometimes it’s easier to lock onto an axis by initially going in the opposite direction than the one you want to pull your model in. This has been the case for me on more than a few occasions.


The trick is to click and release on the endpoint at the cross to start the action, this attaches the point to the mouse and it will follow it anywhere. Tap the up arrow once and it will now be constrained on blue. Move to where you want it and click and release to end the action.


Thanks for the replies. What is the “constrained on plane” message though?


It’s had to know what it was referring to without seeing it in context.
It’s probably just registering the inference of a face nearby.