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I am drawing a greenhouse and must create a 30 degree angle at one end a drawn 2 by 4.

Search to date has not produced an example of creating a precise angle. I grab and move two opposite vertices on the x axes and an angle is created but how to be precise?

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    $\begingroup$ Just create another object with the good angle, then snap this one to it (snap to edge). $\endgroup$
    – lemon
    Mar 10, 2020 at 19:22
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    $\begingroup$ can you not just rotate the face? $\endgroup$
    – Luciano
    Mar 11, 2020 at 11:25
  • $\begingroup$ @Luciano .. No. :) . Try it. $\endgroup$
    – Robin Betts
    Mar 11, 2020 at 12:06
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    $\begingroup$ @RobinBetts Would it be possible with the Shear tool? It seems perfect for the job, but I couldn't make it work :). $\endgroup$ Mar 12, 2020 at 21:37
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    $\begingroup$ @JachymMichal You certainly could use it.. but AFAIK it works only in screen space, so you have to line up the view, and then you have to do the same amount of mental arithmetic to figure out the offset.., so here, personally, I'd just go for the move. Actually, practically, as in the comment to my own answer, If it's that kind of job, I keep jig-objects lying around, just for snapping. $\endgroup$
    – Robin Betts
    Mar 12, 2020 at 21:52

5 Answers 5

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One way to do it numerically, assuming Y up, X across, and starting with the end of your bar square..

  • CtrlC Copy the height of your bar from its Y in the Dimensions panel
  • Select the top edge or point, (whatever will wind up where your arrow is..)
  • GX, and then in the Adjust Last Operation panel, type into the 'X' field: "CtrlV / tan(pi/6)"

You can stash expressions like this in a text-block to copy and paste from if you have to do this sort of thing often, but usually you only have to do this once, the rest is duplicates and snapping.

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    $\begingroup$ Or... just keep half an equilateral triangle hanging around to (uniformly) snap-scale and snap-to. $\endgroup$
    – Robin Betts
    Mar 11, 2020 at 12:07
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You can see the angles by turning on Face Angle in Viewport Overlay (shows all the angles on a face). I was wrestling with this problem a few weeks ago and wanted a certain angle where 2x2s met.

I went in and played around a bit today. Here's my method, more or less. The ones above are more elegant, but this one shows you the angle. :)

Click the Viewport Overlay near the top right corner of the viewport. Down towards the bottom, check Face Angle. This will show you all the angles on a face. Click the edge you want to manipulate (I took the upper right end, use shortcut keys G and Y to move it along the Y axis. (or whatever axis you are lined up with). I was not able to get closer than 30.006 using my mouse and sliding. After that, I had to type in GY 0.0001, check the angle, and try again with a different number until I finally got to 30 degrees.There's probably a better way to do this part. Now that I know how to use the Bool Tools addon, I would probably use the rotated cube with Boolean instead.

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  • $\begingroup$ Tried this method but there are so many numbers they overlap one another making the angle unreadable. May be a configuration problem? I will keep searching. Haven't tried the numbers approach. Next on my list. $\endgroup$
    – Liamdale
    Mar 12, 2020 at 23:03
  • $\begingroup$ Just found another way which is similar to yours using the addon measureit. I selected the vertices to get the current angle of the target corner. Showed it and it registed. Then selected the two vertices to grab (G - X) and drag the vertices to create the required angle. The measureit angle display will adjust its display to show the current angle. kept dragging until I reached a 30 degree angle. Not the best method but it works. $\endgroup$
    – Liamdale
    Mar 13, 2020 at 0:07
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Add another Cube and rotate it by 30° and move it to place. Then add a Boolean modifier to the object and apply it.

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Addendum. This can also be done with Bool tool addon. Enable Bool tool in preferences:

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Open sidepanel and its Edit tab. Select the cutting object first, then select the to-be-cut object. Click Difference.

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This method destroys the cutting object.

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  • $\begingroup$ Tried it and got it to work but there must be a better way. Thanks for the input. $\endgroup$
    – Liamdale
    Mar 12, 2020 at 22:56
  • $\begingroup$ @Liamdale It can be also done with Bool tool addon. Enable it in preferenses and you find it in sidepanel's Edit tab. You still need that extra object (which can be used many times, it doesn't get eaten in the process) but don't need add+apply any modifier. $\endgroup$ Mar 13, 2020 at 8:10
  • $\begingroup$ (Oh actually using Bool tool the cutting object vanishes, you can't reuse it.) $\endgroup$ Mar 13, 2020 at 8:20
  • $\begingroup$ I tried the add-on and found that it works well. True the template is destroyed but I created a permanent 60-30 template saved it and appended it as needed. $\endgroup$
    – Liamdale
    Mar 18, 2020 at 0:31
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You can shear using a formula: tan(radians(90-angle))

So for 30 degrees: tan(radians(60))

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    $\begingroup$ Cool. IMO this is easiest way to put in some arbitrary angle. For the case of 30 / 60 could stick in sqrt(3) $\endgroup$
    – batFINGER
    Mar 18, 2020 at 14:30
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    $\begingroup$ Tried it with both 30 and 60 degrees and it works ! A little vertices management but it works very well. Thank you lemon. $\endgroup$
    – Liamdale
    Mar 20, 2020 at 1:53
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Inspired by Robin Betts's answer, here's another numerical method. This is based on the fact that sin(30°) = ½ exactly. Note the starting dimensions, the 10 cm side is along z-axis in this example:

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Go to edit mode and make sure the Transform Pivot Point is set to Median Point and select the end face of the beam:

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Scale by 2 along z: S Z 2

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Rotate by 60° around y: R Y 6 0

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The horizontal edge stays horizontal:

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  • $\begingroup$ What If the angle was say 33.45634 degrees? Does it matter what order you do scale and rotate step? $\endgroup$
    – batFINGER
    Mar 13, 2020 at 12:05
  • $\begingroup$ I needed a 30 deg at one end and 60 deg at the other end. sin(30) gives 0.5 sin(60) is 0.866. I don't see how much scaling is necessary to compensate the rotation width reduction. Math is not my strong point. $\endgroup$
    – Liamdale
    Mar 14, 2020 at 6:07
  • $\begingroup$ Yes I understand. I mentioned because if its not 30 (just hypothetically) and a simple fraction then scale isn't 2 its 1.8138...(for example angle suggested above), rotate isn't 60 its 56.54366. Typing or pasting these values in is far more time consuming. See the new answer from @lemon that would entail crunching the angle once. $\endgroup$
    – batFINGER
    Mar 18, 2020 at 14:30

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