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How blue print tolerances being read and apply to 3D

Question asked by Ern More on Apr 25, 2018
Latest reply on Apr 25, 2018 by Ern More

There might be a lot of people already asked this , i've already watch several videos "self-learn"


"I am like a customer with absolute zero knowledge trying to understand this product, why,when,where do i use this product in my house"


I'm trying to learn how to make 3D object however i also need to consider the tolerance so now im trying to understand the language of mechanical drawing and trying understand on how to apply it in 3D like Solidworks
Now i have this "tolerances" problem since im not mech. engineer. As to what i understand about tolerance, it provide gap between two solid objects and combine it.
and it can't be perfectly 0.00 zero gap since we have to consider "bend" to avoid problem in fitting two solid objects not unless its (interference fit).

another is the datum tolerance which
any additional info about tolerance would be really great and appreciated.


I've circle in red those i want to ask/clarify/to understand.



In (Question no.1) as to what i understand, please correct me if i'm wrong


Dia .750 is the maximum material condition and the Dia .752 is our LMC 
my understanding is:
its up to me to make this hole with .750 "or" .752 diameter and it is still acceptable.


So if i choose .750 as my hole size
then my shaft possible nominal size would be lesser and then it would be around .747 +.002 -.000.

.747LMC size for shaft

.749MMC size of shaft


For the true position why is it .005? and how do i apply it to 3D model, i may have been understand it but due to too many info coming to my head i got lost/confuse to understand it clearly.
i've seen some videos that true position use datum to control/hold the movement/rotation of the side of the model especially if the sides are not perfectly straight line  or e.g. like corroded metal when you clean it became irregular so basically it has "Datum A(primary which it is the first to hold the object side), B(secondary hold fit so that the object won't move on the side of B), C(tertiary same as A and B purpose hold the side of  datum C)
but in overall how do i apply this true position .005(M) in my 3D model, im still blind on when will i use this 0.0005(M).


and regarding to Datum B which it has also Maximum on its side, does it mean that i have to make a clearance in my hole that allows Datum B to move up and down like i have to choose on my hole size with .752 LMC so that i can have a clearance tolerance.



for question 2 and 3


2. it has parallelism of .001 why does it have tolerance? does it mean that i have to make it 1.000 - .0005 or 1.000+ .005 , which should i choose 1.0005 or .9995? how will i choose?


same goes for Q3.
flatness .0005



i mean (1.000 +/-.001) - .0005 =?

I'm really confuse but determined to understand this language of drawing.
i only wanted to make 3D models but i have to consider tolerance too.


thank you so much in advance.
God Bless.