How to make (mm) the default unit in properties inputs when the scale is set to 1/1000 (mm)?

Support Basics & Interface
1

I’m using Blender 3.6 right now. The following may be a known bug that’s been fixed in more recent versions or something, but I didn’t find anything on a Google search.

Is there a way to make “+ 10” in a Location (X, Y, Z) or Dimension (X, Y, Z) field automatically move by 10 LengthUnit instead of 10 LengthUnit × Scale?

So I’ve been working with 3D printing. The printer I’m using assumes the unit used is millimeters, and the models I’m printing are the right size that millimeters are a good unit in which to measure them. Also, many schematics are drawn in millimeters.

So I naturally set the base units in Blender to “metric, millimeter”. This allows me to type things like G, Z, 5, Enter and move an object up by 5 mm. Yay.

Of course, the actual base units are still meters. So certain things don’t work very well, like Voxel remesh having a minimum size that won’t let me go below 0.1 mm, or input fields on UV mapping nodes wanting to jump hundreds of mm per “tick”, requiring manual input of 1 mm incremental changes to match up textures to geometry, even before fine-tuned adjustment.

So I tried setting the unit scale to 1/1000. Now, the internal unit should truly be millimeters. Except now the object properties pane tries to scale my inputs to 1‰ unless I manually type “mm” each time.

  1. Create new Blender project.
  2. In the Scene Properties tab, open the Units tab.
  3. Set Length to millimeters and Scale to 1/1000.
  4. In the main view window, hit N to bring up the properties pane.
  5. Click the default Cube to select it.
  6. In the properties pane, select the Item tab.
  7. Click a field in either Location or Dimensions, such as Location, X.
  8. Press End or → to set the cursor to the end of the text.
  9. Type “+ 10”, press Enter.
  10. Location will change to 0.01 (we’ve moved by 10‰ of a mm).
  11. Hit Ctrl+Z to undo the change.
  12. Back in the Scene Properties, Units tab, set Scale back to 1.
  13. Keeping default Cube selected, again click the Location, X field.
  14. Again, hit End, type “+ 10”, press Enter.
  15. Location will change to 10mm (we’ve moved by 10mm).
  16. Change Length unit to “inches”, then set Scale to “1/100*2.54”, then enter “+ 10” into the Location, X field, the object will move by 10 (2.54/100) inches.
  17. Leave Scale at “1/100*2.54”, set Length unit to “millimeters”, then enter “+ 10” into the Location, X field, the object will move by 10 (2.54/100) millimeters.
  18. In any of the above cases, entering “+ 10 mm” will move by a properly scaled 10 mm. Weirdness only occurs when omitting the unit.

Clearly we’re moving by 10·Scale of a LengthUnit each time we type +10. But I want to move by 10·LengthUnit each time instead. Is there a way to fix this?

2

OK. I can reproduce.
Problem was not fixed.

You probably should post a bugreport.

The issue is due the fact to type +10, with typing cursor after mention of unit (mm).
If you erase mm letters before typing +10 or if you type +10mm ; there is no issue.

3

(You apparently edited while I was replying, so my reply looks weird after your edit, but the information still stands.)

I’m currently on version 3.6.1 release, dated 2023-07-17 12:50. It’s not the current LTS, but is generally pretty stable.

I disabled all addons to test, then restarted. It does the same thing.

I installed Blender via Steam, set it to 3.6 LTS and downloaded. It does the same thing.

With Blender on Steam, I set it to “none” (which gives me 4.3.2 release from 2024-12-16 21:10) and downloaded. I didn’t copy any preferences from previous versions. It does the same thing.

Note that this only seems to affect “+ 10” in the location field, not if I hit G, X, 10, or directly setting “10” in the location field.

4

Yes. Most of people will hit G, X, 10 or use increment snapping.
And if user is careful enough to type measure, too, issue is inexistent.

So if the bug was already posted ; it probably always had a low priority and maybe was lost.
In UI workboard, there is an uncategorized task about improving float precision behavior, but nothing specific to unit system.

So, you probably should contact a developer to learn more about that.

5

Okay, I added a bug report here. It’s nothing critical, but I thought maybe I was just doing something wrong that could be fixed with a simple setting somewhere.