bandolin posted at 7:25PM Wed, 14 October 2015 - #4233624

I just finished your tutorial on this. I am going through your YouTube channel one-by-one just to get some basic experience with blender. What I really love about your tutorials is that they are short and designed to accomplished a single task, yet within that task you are exposed to a wealth of features. I can tell this is your teaching background seeping through (either by design or by habit). There are a lot of tutorials out there by many self-professed industry experts (ie: blenderguru: great knowledge, poor teacher) but their tutorials fall short as a learning experience because they do not know the principles of knowledge acquisition.

Sorry, that was my preamble. My real comment here is about blender units. You stated the tutorial by describing that this project could be used for 3d printing, however, you were not aware what "Blender Units" equated to in the real world. I guess blender units are similar to Max units in that they are just a proportional relationship to objects within the app itself. However, Blender offers this unique experience that I believe Max does not. The ability to use different measurement in the same scene for different objects.

So, I experimented and each mesh object garnered different results. My hope was to place a cube at 1 blender unit and then add a sphere, let's say at 10 cm to see what it equated to. Each time I performed that action with different mesh objects I got different results. As an example cube and sphere seem to be added consistently at the same ratio in size. But a cylinder changes drastically when unit convention is changed. This makes it very difficult to estimate what a blender unit is compared to real world measurements.

The problem I am faced with real world measurements in relation to your tutorial, if I truly wanted to send it to 3d printing, is that will conventional units actually apply and when you used real world unit (imperial or metric) the objects are so small that the blender zoom feature can only get close enough if in orthogonal mode.

Hi, Bandolin. I'll try to address a few things here, but first I'd like to express my sincere thanks and gratitude for the kind words, and taking the time to go through the tutorials, as you have. I will state up front that my experience with Blender's Unit system has been less than productive so far, and my experience is that some things simply can not be modeled to the same level of precision, in all creation parameters, in the Blender environment as we might be used to in 3dsmax. I feel that this is a relatively minor issue, which will soon be addressed in a future release of the software, but such is the case as it stands now. I have not personally used Blender to 3d print the models in my tutorials, but there have been several people over at Shapeways who have, and sent me photos of the results. Here's one example: Floral Star Ball 3d Print. So evidently, Blender's real world units can be used successfully in the production of real world objects from the tutorials, and a single file (according to documentation) can indeed contain multiple scenes of different units of measure, using the visible layers system. However, I have absolutely no knowledge of creating objects using different units of measure together in one scene, and I'm honestly not sure how it's possible. I know you are correct in that it isn't possible in 3dsmax; and while an object's linear units in 3dsmax can be accurate down to 6 decimals (engineering precision), scene/system units need to be chosen wisely prior to embarking on scene construction.

Again, I have not fully wrapped my head around the way Blender handles scale across the software (I won't get into inconsistencies I've encountered in some parameters), but I do understand that, by default, switching between Metric and Imperial units in Blender can result in some very drastic changes in the scene grid. Of course, this is because when using Metric, the system grid units are set to "Meters", but switching to Imperial, you will be working in "Feet". If a model is created in a 1x1 grid cell under Metric, changing it to Imperial will change the unit to a square Foot, which is of course dramatically smaller, and suddenly your model could be unintentionally scaled down to oblivion. Now, if you place another new object into the current scene, after units have been switched, it will conform to the currently selected unit of measure in the grid space, while the previous object may still occupy the previously proportionate scale from it's own original creation.

I'm not sure if this is the issue you were experiencing when switching scale in a scene?

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