Thanks for finding this, maybe it applies to ISO. It is fairly clear, but I still think my notation is clearer, even if it's not technically correct. And at the end of the day we're trying to convey information, so I'm tempted to go off book in this case.
0.01mm would be lovely but unfortunately we're nowhere near achieving that. I've gone through an assessment and found ±0.15 mm is just about acceptable.
Burunduk - thanks for confirming that. I wish there was someone who knew more about GD&T here.
The spacing spec seems like over constraining but it is needed.
For example, if it wasn't included the spacing could be as bad as 1 ±0.6 mm, with absolute position of one line at USL and the next at...
Hi,
First up I'm an ISO guy.
I have a shaft and I want it's axis to define my datum A. The caveat is that I only want a section of the surface be used to define the datum - the first 110mm from on end.
see this image:
So I've got two locations defined already, K and L for another feature. I...
So I think I'll go with this for defining the absolute position of each mark.
My question is whether I need the datum A? or would B be sufficient?
I only included A to orientate the datum, but is that making it more confusing?
The other dimensions are taken care of here.
ctopher:
Laser...
That does make sense, but it is also quite confusing and sounds like a source of problems.
If I spec it as a position instead would it be the same?
Does this mean all outputs are positive and agnostic of direction?
I'd quite like to know which way the marks are out by, so perhaps, for once...
I guess inspecting this should give a list of measurements like so:
"61" Line | 0.02
"62" Line | 0.21
"63" Line | -0.10
"64" Line | -0.35
... etc for all lines.
I'm guessing the reported value would be the larger deviation from the nominal in either direction...
shamed... I have done it properly elsewhere on the drawing I promise! :) we all know what I mean tho.
ahh so I should really be putting a datum on the end face too, though it is the the axis (A) that defines the orientation, so maybe the position should be to A B like: |pos|Ø0.6|A|B| ?
Hi, thanks for the speedy response.
I had a go putting position on it, see below.
I'm not sure if this is very clear though as I think it could be interpreted as inspecting all the 1mm increments, rather than all the absolute positions.
Also:
- this part is a round bar
- the spacing and...
Hi,
So I've found one of those "sounds simple at first" problems.
I have a part with a laser marked scale, imagine a glorified ruler.
I need to specify the tolerance of the laser marks, specifically three things:
- Absolute position of each mark from end face
- Line Spacing between adjacent...
Yes, I think you're right, got the wrong idea there for some reason.
My part is a little outside of the descriptions in 8888 being a rod bent into an S shape, but I think if you squint real hard, it's sort of a plane, and the spirit is there regardless of the feature.
I work in ISO but am making a part I wish to inspect with a gauge.
I want to describe the primary datum plane, and I want it to match the simulated datum plane of the gauge. So the granite table top so to speak.
However, I believe that in ISO a datum would be defined by the derived median...
Now I think I'm getting a grasp of orientation planes, I guess the top 8 +2 (E) dimensions could also be described with position, but just with a parallel orientation plane. (slight change to the tolerance due the the MMR but this can be modified with the pos tol)
so this is identical:
Only...
Okay,
So I've got this now, which I admit, find a bit disgusting, but I do think it's accurately describing the situation:
So the top 8 +2 (E) dimension is there to check the bends are done in the same plane (for a part with 2+ bends). Could be easily checked by placing a parallel on a couple...
yeah I see what you mean, and I actually cropped out the top one by mistake which I had set to (8), so a reference, none diameter, to help try and distinguish the datum plane, and the bent axis of the part to which the position applies. see what I mean below:
Is the a symbol I could apply to...
So perhaps this then?
So to me this is implying the axis of the bar is to be confined by the blue tolerance planes shown.
Not having the diameter symbols on the position tolerance makes sense, but I don't see what's wrong with having it on the 8.
Couldn't you also tie it to Datum A like so...
Hi jassco,
The only ASME I've got is GeoTol Pro but I can seem to find any reference to bidirectional positional tolerancing.
This is what I think I need to do in the ISO:
I don't think I really want to control orientation, just the form.
Could I do it by controlling the axis instead like so?
I think it's the same, it's basically straightness applied to a non flat surface right. But in my case I don't actually care about one side.
I see what you mean about it being 13mm not 18mm now as it describes the tolerance width. Maybe there's a better way to define this...
Hi Jassco, ISO is a bit of a pain due to how dense the language is and lack of clear examples.
You've misinterpreted the intention of the drawing which means it's probably not correct. At least we're learning.
I think the problem is the orientation I want the profile of a line to control is...
