Math question.

[[Er...]]

How do you mathematically determing if a deviation from nominal is positive or negative?

You have nominal xyz and a vector direction, and of course actual xyz.

Does any one have a solution?

[[Ja...]]

Eric,

You can have smaller than nominal X but larger than nominal Y, larger than nominal Z but smaller than nominal Y, etc....

I'm not sure exactly what you are looking for. To combine all three you could find the length of the radius vector to nominal point and to actual point and then compare. I'm just not sure what that would even tell you, practically speaking.



For example,
Imagine we are measuring the unit sphere. (0.5774, 0.5774, 0.5774) will be an approximate nominal point (sqrt(0.5774^2 + 0.5774^2 + 0.5774^2) ~ 1). Now we measure an actual point of (0.5752, 0.5785, 0.5779). This point will be at a distance from the origin of sqrt(0.5772^2 + 0.5785^2 + 0.5779^2) ~ 1.0009.

Now, would we say that this point is greater than nominal (or, deviation is positive) because it falls outside of the unit sphere?

[[Me...]]

(devX*nx)+(devY*ny)+(devZ*nz)

Enjoy!!

dist=getParameterNamed((getActual("Pnt1").vector-getNominal("Pnt1").vector)*getNominal("Pnt1").normVector.asStandardVector
display(dist.x+dist.y+dist.z)

[[Ro...]]

i always think of + and - as in MIn & Max as max is outside the cad model and Min is inside the model.
Or saying max deviation would be material heavy condition.

But put that in a formula...... (If_Its_big_its_Max)+(If_Its_small_its_Min)???? my Ti85 wouldn't process that

[[An...]]

Please sign in to view this quote.

That's right!
See Excel-file.

Contribution_21_06_2019.xlsx

[[Er...]]

Thank you Phillip, thats exactly what I was thinking of. So simple, yet I could not figure it out.

May I ask if there is a relation between this and Pythoragos? I find it hard to explain what Im asking in english. But why does multiplying with the vector and sum up the values work? (If that question make any sense..) I get why it gives a positive or negative value, but not why its correct.

Again, thanks!

[[Me...]]

I'm no Matt Damon (Goodwill Hunting), but I would say that there is a relation 😉 . Here is a crude sketch that should help with the visualization. I've also included a couple of links that helped my understanding.

https://www.youtube.com/watch?v=LyGKycYT2v0

https://dpprog.wordpress.com/2017/07/09 ... evelopers/

[[He...]]

Please sign in to view this quote.

Thank you very much. I had to do this s few year back when I wanted to create a function to evaluate a curve with a non-uniform tolerance. Just to get the deviation was easy enough but to get the direction of the error was a son of a bitch. I ended up with a real shit-show where I used the biggest of the three vectors and a few if-conditions to determine of it was + or -. Needless to say it takes a long time to calculate a few 1000 points. (Like saying something in Old Entish).
With this and some other improvements I'm sure I will reduce the time with at least 80%

[[Me...]]

Please sign in to view this quote.

I feel your pain!! I had to evaluate a non-uniform wall thickness, and the curve distance characteristic was not going to work for my application. I ended up writing a ton of unnecessary code to get what I needed. Just as in your case, the first attempt was a complete mess and it took close to 20 minutes to crunch all of the numbers.

I bet you'll find yourself using some variant of this code more that you would initially think. It came in handy on a program I wrote to correct disk probe qualification values.

To Whom It May Concern:
How does one become a "Dear Friend of Benny" 😎

[[An...]]

Please sign in to view this quote.

Just want to support this sketch.

Contribution_25_06_2019.pdf

[[Er...]]

Very informative video, ones put in context the coin entered the slot.

And this linear abracadabra is the whole reason I like to have a matrix syntax. Then monkey doesnt need to think. Monkey only do.

Benny says to wait a couple of days, a new updated one is a day or two away. Then contact him again.