Question about tolerance

Hi dears i have two questions about tolerances:
When i use this unit :(Units: Millimeters -Absolute tolerance: .001 mm)

**1.**When i draw two side by side plane and move one of them 0.002 unit , and then if i want to join this two plane there is no problem but .002 is out of tolerance.why this happen?

**2.**As you see in this two picture below :
in picture.1 Maximum deviation is 0.000836217(in tolerance) and intersection object is not complete but in picture.2 Maximum deviation is 0.00471085 (out of tolerance) and intersection is complete.why?

                                                                                 picture.1

picrure.2

Hi Shayan - each edge can move .001 to find a joined edge location.

-Pascal

Hi dear pascal
i did not understand your intention.can you more explanation ?

Here’s a link to an FAQ which should prove helpful:
http://wiki.mcneel.com/rhino/faqtolerances

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Hi Shayan - ‘Join’ can move a surface edge away from the surface - generally this should be minimal, hence the Join tolerance ( you can override the tolerance with JoinEdge (generally a bad idea) and join surfaces that have edges that are far apart - you’ll see the edge move) So, Join will not do this- it will not move an edge more than tolerance away from it’s ‘natural’ location. .At 001, join allows each edge to move that distance. Does that make sense?

-Pascal

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Appreciate John Brock and pascal for your attention
your answers was very useful

Hi dears i have a problem
last 5 month i started a modeling in (Units: Millimeters Absolute tolerance: .001 mm) but now i realize that i made a mistake and my unit is in (Units: Millimeters Absolute tolerance: .01 mm) is there any way to dissolve this problem?
-thanks

I wouldn’t necessarily call that a problem.
How big is the smallest feature of the model?

You could just tighten the tolerance now and keep modelling. If you start running into naked edges you will have to resolve them at that point.

The other alternative is to explode everything into individual surfaces and use the RebuildEdge command to rebuild them to the new tolerance. Then join things back together and see if you are getting naked edges.

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Hi dear wim
appreciate for your attention and .excuse me for my very long time delay .
Before i create this topic i didn’t have enough information about tolerance but now after reading your answer ,other friend’s reply , Mcneel Wiki ( Understanding Tolerancesto ) and online help of Rhino site i know tolerance very better but i have some question.
1. i read in Rhino online help :
In general, Rhino works best if you choose a unit system whose absolute tolerance is around 0.01 to 0.001, the
"size" of a small feature (like a tiny fillet or small curve offset distance) is >= 10 x tolerance, and the “size” of the model is<= 100000.
In addition to tiny fillet or small curve offset distance ,which command have small size feature?

**2.**i read in Mcneel Wiki :The relative tolerance is used on a few commands and can generally be left alone
witch command use relative tolerance and what is the different between relative tolerance and approximate tolerance,?and what does it mean “can generally be left alone”?

**3.**You said use join,explode and rebuilt edge for changing the tolerance.is there another command that be useful for changing tolerance ?

-Thanks a lot

Basically any command can have a small size feature. You can e.g. draw a line that is 0.0001 units long.

I don’t know which commands use this and what the difference is. In the next version of Rhino, Relative tolerance is removed from the Document Properties - a user cannot change this setting anymore. [quote=“shayan, post:10, topic:34754”]
is there another command that be useful for changing tolerance ?
[/quote]
Not that I can think of right now.

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Thanks a lot dear wim for your useful answer