Angle measurements

[DaveR]

Hi All,

As a relatively new user, and with a physics rather than an engineering background, I have been trying to understand the angles reported by PCDMIS and have become rather confused.

To keep things simple, I started off by creating a generic line in the XY plane at +5 degrees to the +ve x axis and then report its angle to the x axis and to another generic line also along the +ve x axis. My confusion comes when I have 4 measurements of essentially the same thing, but 3 different answers of -5, +85 and +5 (see the code below). I understand that -5 and +85 are essentially the same number (give or take 90 degrees) although I cannot see why what looks like the same measurement gives two different answers. What really troubles me is the +5 degrees where I expected -5 degrees! Surely PCDMIS recognises the sign of the angle?

Has anyone out there experienced similar problems and have any solutions to offer?

I am using PCDMIS 3.7 MR2

Dave

*********Sample code********

LINE_X =GENERIC/LINE,DEPENDENT,RECT,$
NOM/XYZ,0,0,0,$
MEAS/XYZ,0,0,0,$
NOM/IJK,1,0,0,$
MEAS/IJK,1,0,0,$
DISTANCE/11,12
COMMENT/DOC,NO,
,Generic line in xy plane at ~+5 degrees to x axis
LINE_P5F =GENERIC/LINE,DEPENDENT,RECT,$
NOM/XYZ,0,0,0,$
MEAS/XYZ,0,0,0,$
NOM/IJK,0.995,0.1,0,$
MEAS/IJK,0.996,0.088,0,$
DISTANCE/12,10

COMMENT/REPT,********************************************* *********************
,Workplane ZPLUS...
,************************************************* *****************
DIM ANGL13= 2D ANGLE (TRUE) FROM LINE LINE_P5F TO XAXIS ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
A -5.739 0.010 0.010 -5.059 0.680 0.670 -------->
DIM ANGL19= 2D ANGLE (TRUE) FROM LINE LINE_P5F TO XAXIS ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
A 84.261 0.010 0.010 84.941 0.680 0.670 -------->
DIM ANGL5= 2D ANGLE (TRUE) FROM LINE LINE_P5F TO LINE LINE_X ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
A 5.739 0.010 0.010 5.059 -0.680 0.670 <--------
DIM ANGL14= 2D ANGLE (TRUE) FROM LINE LINE_P5F TO LINE LINE_X ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
A -5.739 0.010 0.010 -5.059 0.680 0.670 -------->

[#2#]

Greetings fellow student of physics. I too came from schooling in physics.

As for PC-DMIS and angles... I have never sat down to figure out how the vectors and order of feature selection influence the results. All of your results mean the same thing execpt for the 84.9º one. I don't know where that came from. It should either report 5º or the complimentary angle (175º) or positive/negative of either of those.

Here is my trick for getting to report what I want. When you dimension the angle, I assume you have the little angle window open. Select your feature(s) and/or your axis. Then, before you click on "create" input your nominal (5º in this case) in the field provided. I have found without fail that it will then spit out the correct angle and not a complimentary one.

[DaveR]

Goodluck,

Thanks for your reply.

My real worry was that all the measurements were from my line to the x axis, so should all be -5 degrees (or maybe +85 or +175, although I can't really see an excuse for those here).
What I cannot see is how PCDMIS can report +5 degrees - it looks as if it is losing the sign of the angle which from my reading of the help files it shouldn't do.

Dave

[sdvannoy]

Are you sure ? If you will look at my new post , maybe you can answer my question .

[dwade]

Dimensioning angles has been one my hardest to figure out with PC-DMIS. Sometimes it works like should and other times I can't can't get it straight if my like depended on it so I work around it.

I use trig for most of my unless it is so basic I can't screw it up.

For instance, ASSIGN/V1 = RAD2DEG(ATAN(featurename.I/featurename.J)) will give you angle of your feature working in Z plus/minus. then create a gebric feature using "None" as these are the only 2 that allow me to input the angle. Then tolerance the feature.

Duane