Sa-Ro,
Assuming your part is fully defined, it does not matter where you place your basic dimensions. So both methods would be correct. However, Method 2 should be preferred.
Please see the following video: https://www.youtube.com/watch?v=AfgBF0VKpbs&t=13s
MattEdwards,
On a different note, you should consider |A|B|C⯈| as your DRF if you are using 2009 or 2018 version of the standard. This also usually indicates that the datum features are not "selected" correctly.
Burunduk,
Yes, the line there is also an axis. That's my point, there is no difference. Maybe I can re-formulate the question:
Could we call "line-in-plane" "axis-in-plane", and "point-on-line-in-plane" "point-on-axis-in-plane" instead? What does the term "line" add to the definition of a...
Burunduk,
Thank you for the explanation.
In that 'line-in-plane' example with the wedge, I would still call it an axis, rather than a line, because it is the intersection axis of the the 2 planes (actually 3 planes: 2 wedge planes and the symmetry plane).
So to me, all datums come down to...
Burunduk,
I am having difficulty understanding what a datum line is. Is the term `line` used for curve, like in `median line`? To me, the difference between a datum axis and a datum line would be that the line would have 2 end points (fixed length), where the axis would have an infinite...
Garland23,
Datum Reference System = Coordinate System (cartesian), which consists of 3 datum planes, 3 datum axes, and 1 datum point. So a datum plane for instance is just a part of the Datum Reference System.
3DDave,
If you think a datum point as intersection of 2 mutually perpendicular planes, those planes do not have to be fixed, they can freely rotate around the intersection axis, until the secondary, and tertiary datums come into play.
Even if you have just a cylindrical feature (datum...
Garland23,
A datum axis is a single datum, but can be thought as the intersection of the 2 mutually perpendicular planes.
Same thing as a datum point, thought as the intersection point of 3 mutually perpendicular planes.
Burunduk,
1. What is the difference between a datum axis and a datum line?
2. For a conical feature (identified as a primary datum feature), would we have 2 datums (1 datum axis, and 1 datum point) or 1 datum (datum axis and datum point counted as 1 datum)?
ETUDEN,
- Datum feature B is missing.
- I think 0.15 flatness should be a Profile of a Surface, unless you do not care about coplanarity. Also, add 3X to the FCF. I would also remove the datum feature flag for A (no need since the 3 datum targets are very clear).
- It would be much better if...
Hi all,
Referring to the image showing 6 possible datums:
There are only 3 possible datums: point, axis, and plane.
It is important not to mix datums with datum features and/or simulators.
Woosang,
It looks like your question is about a theoretical part, which is perfectly fine. I want to point out that next time please include the standard the part should comply to, like ASME Y14.5-2009 for instance.
Looking at the part, the full DRF should be | A | B | C> |, where `>` stands...
Please note the difference between
A | B(M)
and
A [BSC] | B(M)
and
A (M) | B(M)
You may want to consider the last two.
Please also note that the primary datum will be a plane, not an axis. So you will have to show your plane on the drawing!
Thanks.
ANBU SARAVANAN,
Probably, the designer intended for more stability. I hope this video will shed some light:
https://www.youtube.com/watch?v=zRLwzfg9Q1Q
cr7,
Coaxiality is a location control. Orientation (parallelism, etc.) does not control location. In order to control the coaxiality between these two cylindrical features, you will need a POS, or a PROFILE of a SURFACE, or a RUNOUT (circular or total), or a CONCENTRICITY (note: concentricity...
Hi all,
In the drawing posted by OP (which is a new tip from Tec-Ease), the datum is apparently the tangent plane (based on ASME Y14.5M-1994, Y14.5-2009, and Y14.5-2018). I do not understand why the datum is not the axis of the cylinder, which is the datum feature. Can someone please explain...
