Hi. I from iran . Sorry for my english
Check this pictures .
After move object to far of The world axis.
For example: cube move to 600M (X) (Y) or (Z). In edit mode extrute 1 Vertex .for make edge
D=1.2 (1 M 20 Cm)
After set . ( Measure tool ) . To lenght of edge .
Edge lenght changed to Ex:
1M 19955 cm
1.19955 M
In micrometer ex: 1.1978636
Inaccuracy of values
Please i want to fix it
Blender 2.81
Why ?
Sounds like floating point errors to me which pretty much canât be fixed other than by upping precision of every single distance to double, also doubling memory usage in the process and making it all less efficient on most graphics cards.
What should I do?
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You probably have to live with it. All 3d apps I know have have this issue.
If you really need that insane precision, youâll need some specialized CAD application which works with double precision. This is not a goal of Blender.
A thing you can do within Blender is to change the unit scale. If your project is like around a meter in size, you can make the base unit int decimeters or centimeters, meaning huge distances (kilometers) are gonna be less accurate but tiny ones (millimeters) are gonna be much better.
On the flip-side, if your project is gonna be HUGE (entire landscapes) but youâre never gonna be zoomed in all that much, you might even wanna go the other way, upping the unit scale but further sacrificing very fine detailsâ precision.
For what itâs worth, the errors youâre getting here are on the order of a hundredth of a millimeter (10 micrometer) which is also roughly an order of magnitude beyond the resolution limit of your eyes. Meaning for the vast majority of cases, this is entirely fine.
Aha . Ok ⌠Why canât it(blender) look like cad⌠aaaaa whyy
I already told you: Itâs less efficient and not a priority. CADs are very specialized software for high-precision work. They sacrifice some performance to accomplish this (requiring beefier hardware to run smoothly with reasonably sized projects)
3DsMax is beter then blender for precision modelin ?
I love blender . I cant go to 3dsmax
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Please send feedback to blender foundation for cad precision modeling feature . 
I donât think 3DSMax is better in this regard than Blender. Not sure about the tooling, but precision is likely gonna be the same.
AutoCAD is gonna have higher accuracy though, Iâd think. (I donât actually know but since itâs actually made for CAD, that seems likely)
And thereâs a free version of that.
This sort of confusion is common when dealing with computer math. Usually, it shows up as âWhy is this result 1.9999999 instead of 2.0 like it should be?â The answer is âcomputer numbersâ.
Computer numbers look and act like the Real numbers we know from math class, but they are not.
Real numbers are infinite (for any given number, there is always a bigger one).
Real numbers are continuous ( there is always another number between any two given numbers).
Blender numbers are Single Precision Floating Point. They are represented internally using 32 bits.
This means they have a maximum range of roughly 10**-38 to 10**38.
They are also âgrainyâ (not continuous) and have an accuracy of roughly 7 significant digits. Both of these properties come from the fact that only a fixed number of bits are used to represent the precision.
Please send feedback to blender foundation for cad precision modeling feature .
Donât bother. It is not going to happen. Blender is an artistic tool. The important thing is that stuff looks good. If you really need micrometer precision, you want software that uses double precision numbers, like a CAD tool or something scientific. AutoCAD, for example.
