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When designing physical objects (mostly for 3D-printing), it is a usual scenario that I create an object with a hole and try it and then resize the hole if it doesn't fit.

I use boolean modifier for hole making, but it is very inconvenient to resize holes made this way since I have to undo the boolean modifier and removing of the cutter mesh (usually a cube or a cylinder), resize it and make the hole again. At times I just don't want to keep hole cutting as the latest action.

What can you suggest a better approach so that I can easily apply trial-and-error method for doing holes (or, in other words, resize them)?

Edit: For example, in the following file there's a piece with 3 holes, the big one is supposed to get an aluminum tube of 8 mm diameter inside it so I've made a 8.1 mm hole (ok, 8.1 cm in the default scale) but it may happen that it's not large enough and I will need, say, a 8.2 mm hole. I kept the hole-cutting cylinder and the painful part is: I applied the boolean (difference) modifier thrice (to the big cylinder and to 2 smaller parts) so changing the hole diameter will be long and annoying. Increasing the diameter is easier: actually, I don't have to undo hole cutting, but to reduce hole diameter, it is required.

enter image description here

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  • $\begingroup$ Could you post some example in edit? $\endgroup$ – cgslav Aug 25 '16 at 22:39
  • $\begingroup$ Well, there are many kinds of holes, I suppose. And then the Boolean Modifier tends to create ngons, which aren't good for printing. How about some screenies? $\endgroup$ – metaphor_set Aug 25 '16 at 22:44
  • $\begingroup$ Right, I've added the latest example as both .blend file and a screenshot. I surely would like to hear suggestions about better ways for printing, although I'm not sure why ngons aren't good for it. $\endgroup$ – YakovL Aug 25 '16 at 22:57
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Constraint Axis Scale

If your holes shapes are made by subtraction of extruded profiles along a single axis, you may consider the option to simply scale the faces in the 2D space of the plane perpendicular to that axis.

enter image description here

This can be done by pressing Shift just after the Scale shortcut (S) and before picking the normal axis (Z in the shown example), or by using the operator panel options.

If you need to use a different orientation than Global (e.g., local, custom, etc.), you'll have to press the keyboard combination (S -> Shift+Z) twice.

The animation above has Edge Length checkbox enabled in order to make the diameter length visible during the transformation.

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  • $\begingroup$ Could you clarify how do you select all the inner faces of the hole at once? $\endgroup$ – YakovL Aug 26 '16 at 13:03
  • $\begingroup$ Also, could you point how can I apply that to my detail from the example (try it, the big hole is cut in 3 parts, not one, and scaling the hole for the 2 others seems problematic). Should I group them or smth else? $\endgroup$ – YakovL Aug 26 '16 at 13:15
  • $\begingroup$ If the internal faces are defining a Face Loop you can select them by pressing the "Alt" key while right-clicking the edge between two faces. (See for example blender.stackexchange.com/questions/22916/…) $\endgroup$ – Carlo Aug 26 '16 at 15:28
  • $\begingroup$ About the big hole, you must join the three object in one in order to edit them simultaneously (just select the interested faces from all objects and perform the scaling) i.stack.imgur.com/lficm.gif. The two tiny holes are correctly scaling i.stack.imgur.com/dsnhz.gif, they just don't have flatten ends. Btw, I would not easily abandon the Boolean workflow...it allow a more flexible workflow in my opinion. Also beware that if you would like to print the objects in single piece, you should model that way, without intersections. $\endgroup$ – Carlo Aug 26 '16 at 15:46
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  1. Make Cylinder with Cap Fill Type > Nothing.
  2. Go to Edit mode Tab.
  3. Select all faces A.
  4. E + S then Shift + Z resize it and apply.

Now you can select inner or outer faces and with the same key combination make hole bigger/smaller.

gif

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In my opinion, while boolean operations have great utility in some cases, this is not one of them. I'd approach this issue by using a different workflow, creating the three interior holes in the piece first, and then extruding from the inner holes to make the outer shape.

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