Perpendicularity Plane to Plane - Straightness included?

[[Ca...]]

Hello,

perhaps somebody has an idea or even a source of knowledge. If i have a recangular steel paar .. for example L = 100mm, B / H = 20mm (the part is heavily bended - like 0.5mm for example).. on the top of my 20mm is my Datum A and i want to check the Perpendicularity to one of the other 20mm planes. (i know sounds confusing, but im not sure how to descirbe it better).

If i have a perpendicularity tolerance of 0.01mm and a straightness of 0.1mm ..

When i use know the perpendicularity reference frame and check my "bended" plane to my surface A, my perpendiularity will be out because of the heavy bending, as we checked it plane to plane and not plane to line (which could be in).

So can we say in the end, perpedicularity plane to plane includes flatness, straightness, form of the desired plane?

Would be really nice if somebody would had the same struggle,

thank you..

[[Mi...]]

This is the type of question where it likely matters ISO or ASME.

I'm pretty sure I know the answer for ASME, but it wouldn't surprise me if it's different for ISO

So which is your drawing?

[[DW...]]

Isn't perpendicularity a form and location control and straightness is just a form control?

[[Ca...]]

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In this case ASME is correct, to be honest is there a big difference in this time with the evaluation?

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This is also my understanding, so when i would have a 0.5mm straightness then i couldnt archive a 0.01 perp with this plane or?

[[Ma...]]

If you are measuring planes, then indeed flatness plays a role, because you are placing two perpendicular planes to base with a distant from each other as tolerance band.

If you have only one base, then it will rotate and move to get best result, but flatness will talk then.

[[Mi...]]

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Then the Form tolerance being higher than the Orientation tolerance makes no sense to me, because Straightness/Flatness are components of Orientation. You can test this by changing the evaluation method of the toleranced plane in the characteristic, your result shouldn't change because it's from the points... not the calculated plane.

Unless Tangent Plane Modifier is used, which can be done in Calypso.

[[Ca...]]

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Thank you for your reply, this is correct,. the form tolerance (straightness) is higher then the perpendicularity.. from my point of this is a drawing error, or double tolerated, the 0.01 perp should be enough to judge (for sure you could ask flatness on all planes to see which has an error)..

at least, thank you to know that im know wrong hehe.

So, after a bit more deep diving i can say that yes, it is something like a double tolerance or drawing error.

If you have 0.01 Perp on your drawing and 0.1mm straightness, your perpendicularity can not be in, if your straighness is already out. As Perpedicularity is evaluated between 2 planes, which means flatness is also included and in flatness is also straightness included (and there the circle is closed hehe.)

Thank you all for your support.

[[Ma...]]

Here is an article I wrote on flatness
https://cmm-quarterly.squarespace.com/a ... rev-3-book

Flatness (form tolerance): the tolerance zone is limited by two parallel planes a distance t apart.
Implies: Straightness of the surface or Straightness of the derived median line