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I'm new to Blender. I'm using it for 3D printing. and I'm trying to do something I thought would be easy but cannot figure out how.

The basis for the thing I'm trying to print is a sandwich board. I cannot figure out how to move vertices to precisely where I want them. I want to extend the one face so that the two vertices reach the ground. (I added a plane to represent the ground for clarity in the picture below.) Moving these vertices will also result in the bottom of this side of the sandwich board resting fully on the ground.

In non-Blender lingo, I want base of the sandwich board to lie entirely on the plane defined by z=0.

The vertex slide seems really close, but it's missing two things. If you can slide it off the end of the edge it's on, I can't figure out how. And if you can tell it to slide no further than a given plane, I can't figure that out either.

I tried doing this with BoolTool and creating sacrificial cubes to cut the bottoms off the sandwich board. I found that the more I used BoolTool, the more I ended up with erroneous or superfluous vertices.

I know I could get out a pencil and paper and a trig table and manually calculate the vertex positions, but it seems there ought to be a way to do this.

(Another way of looking at this is that I want an extruded parallelogram, though I see myself having the same problem, just with one vertex instead of two.)

I'm open to alternative ways of doing this, too.

edit: I'm on Blender 3.2.0.

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edit: This is what my Snapping settings look like.

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Becca
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    You might find Transform Orientations -> Normal useful with some playing around it allows to move parallel to the face. And to put edge at exactly z=0 you could use trick with scaling on Z axis with respect to 3d cursor which is at your wanted Z height by setting scale to 0. You might also find custom orientation useful: https://youtu.be/ABayYXu7OfI?t=456 – Combinacijus Dec 27 '22 at 03:34

2 Answers2

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This looks like a job for Snap > Project Individual Elements.

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It's not incredibly well documented, but seems to work best projecting down an orthographic view, in line (on the left, below). You can achieve the view, looking through the back of the face to be projected, by selecting the face, and hitting ShiftCtrlNumpad 7.

Once there, just tap G once in the aligned view, and the face will project:

enter image description here

Robin Betts
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  • Thank you so much. I think this is going to be the answer, but I can't figure out all the steps.

    So I can open up the Snap thing by pressing Ctrl-Shift-Tab. When I do that, I don't get any "Target Selection" area. Any thoughts?

     – Becca Dec 28 '22 at 01:47
  • I think a remarkably facile step-by-step instruction list would be perfect for where I'm at with Blender. Thanks again :) – Becca Dec 28 '22 at 01:50
  • Oh, I added my Blender version to the question: 3.2.0. – Becca Dec 28 '22 at 01:55
  • Okay. I just found https://www.youtube.com/watch?v=4cehZJkW7MU and saw that there's a menu-thing in the header AND a toggle button that looks like a magnet to turn snapping on! – Becca Dec 28 '22 at 02:07
  • Okay. I have it, though my Snap To settings are different from yours. I'm going to edit my question to include what my settings look like. But then I used GG from @Henrik's answer. – Becca Dec 28 '22 at 02:11
  • Hi @BeccaDee,, yes the tool is not the easiest to use.. Blender's snap system could still do with improvement, IMO.. we really need some way to constrain target and direction. – Robin Betts Dec 28 '22 at 08:48
  • Thanks @RobinBetts. For what my specific task, the way to constrain direction was edge sliding, but I do see how that may not be a general solution. – Becca Dec 28 '22 at 15:26
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Short answer

G,G and drag back, then hold ALT and drag forward while pressing CTR to snap to the underlying surface*.

Long answer

  1. Press G, G to initiate Edge Sliding.
  2. Slide the verts back (or up in this pic).
  3. Press and hold ALT to extend the sliding path along the normals.
  4. Drag the verts to where you want. They'll be aligned with the normal of the edge.
  5. If you want to snap to another surface, press and hold CTR to initiate momentary snapping.

*Prior to pressing CTR, make sure to set Edge and Face Project in the Snap To settings.

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Henrik
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  • Hi hi. Just wanted to let you know I recreated the mesh and I'm not getting the extra vertices, so I'd done something else wrong prior that got me the extra vertices. It's still unclear to me how I can get the vertices to stop sliding precisely, though. – Becca Dec 28 '22 at 01:59
  • So! I discovered GG works with snapping as described in @Robin Betts' answer. – Becca Dec 28 '22 at 02:11
  • @BeccaDee I included a gif that shows more in detail how I'd do it. What's been added in the gif is some notes on how to snap correctly to the surface, which I forgot to mention in my original reply. (The C key while moving things means you don't have to permanently check the Snap button; it instead works a momentary snapping while you hold the C key, which is what I personally use to prefer.) – Henrik Dec 29 '22 at 03:31
  • @HarryMcKenzie Gosh! How good you brought that up. I actually mistakenly used the wrong key (C) which is the equivalent momentary snapping key in Maya! I've corrected both the gif and the text description to reflect the right key, which is the Control key. – Henrik Jan 05 '23 at 11:11
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    @Henrik nice! but how did you know u had to press Ctrl? hahaha kidding. awesome man! thanks alot for your updates! much appreciated! – Harry McKenzie Jan 05 '23 at 11:29
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    @HarryMcKenzie To answer your question, though, about where the momentary snapping key can be found. This operation – what I call 'momentary snapping' – is actually called Snap Invert in Blender and it means you invert whatever snapping state you're in. So if snapping is turned Off, it'll be turned on, momentarily. It appears this feature is undocumented in the current manual as well as not visible when searched for ("Snap Invert") in Preferences > Keymap. But it can actually be seen in the bottom sub-header of the viewport, as shown here: https://i.imgur.com/tfhkMFm.png – Henrik Jan 05 '23 at 11:31