Burunduk, thank you for the explanation. I understand the function of each datum in terms of constraining the degree of freedom.
3 datums can set up a datum reference frame with 6 degrees constrained.
My confusion is about the necessity to relate the all types of features to 3 datums.
Actually...
Thank you so much! You related datum C to datum B for the 4±0.1 dimension, that's a good practice. I did see lots of drawing specifying 3 datums for all features. But I'm confusing when it is applied to features like mid-plane. I can't figure out the process of relating the features to the 3...
Thank you! I'm not familiar with the measure instrument. Could you introduce a bit more about vision system. To me, a vision system cannot handle 3D feature, while the features are constrained with more than two datums, they are 3D feature perpendicular to to datum feature A.
For the original...
Thank you drawoh!
1. For the original design, do you think it is problematic to apply 3 datums for the positions.
We are constraining the mid-plane of the pins and mid-plane of the bock. To me, the mid-planes can only be constrained with two datums, the 3rd one make no sense.
Especially...
Thank you Drawoh for continuously following up this topic. I understand the design intent but don't know what would be the test way the tolerance this part.
Will edit the original post and explain the design intent for all to better understand.
Hello!
I've posted this in a wrong group.
Now I'm reposting it here wondering professional answers and suggestions from this group.
Thank you in advance!
I got confused if the drawing attached is correct or not, actually the 1st drawing was from my customer and probably their drawing follow ISO...
Thank you!
I also prefer the proposed drawing 2.
However I don't understand you statement about LMC.
The two tabs are external features, I apply MMC to the 0.25 positional tolerance so when the actual tab size departs from MMC state, they would gain more position tolerance.
When the tab size is...
Thank you! Yes the tangs are two flat pins actually. They will fit into two PCB holes.
The design intent is to position two tangs to each other.
Do you think the 2nd drawing or the 3rd drawing is better?
Thank you drawoh! I also believe the tolerancing in the 1st drawing is wrong. I agree datum should be applied on feature of size. In terms of function,.the two tabs act as interface to PCB and the distance between them are supposed to controlled. As a group, they can shift. So I would like to...
Thank you! In this case it is not a machined hole. Actually the two rectangular tabs are flat wires. We understand the design intent, just wondering what is the best way to tolerance it. The initial drawing seems to be wrong.
Thank you! It's not a CNC machined part.
It's an assembled electronic component with an upper block and two rectangular pins.
Need to to control the relative postion of the two pins and the alignment between the upper block and the two pins.
Thank you! Yes it is really a simple part. Actually it is an electronic component with two rectangular pins.(two tabs as you described)
What is confusing me is the way how we should define the postions.
Here is the design intent.
This component will be mounted on a PCB so the two rectangular...
Hi I'm a new user of GD&T and recently I got confused about a partner's drawing and I would like to propose some change.
However, I got no confidence about my proposed change.
I googled a lot about positional tolerance trying to find some explanation of similar case.
But, all the posts...
