create point at intersection of 2 circles

[dtmtim]

I have 2 circles constructed as generic features. The circles are coplanar and intersect each other at 2 locations. I am confident the circles intersect because they both have the same normal vector of 0,0,1 and the Z values of the circles match exactly because I used a fixed value for that when the circles were constructed as generic features. Only the X and Y values differ and are based on measured variables. I have to create a point at one of the intersections of these 2 circles. Any ideas?

Thanks!
t.

[craiger_ny]

Check this thread out. Having the same normal vector is no assurance that they intersect. If the distance between them is less than the sum of thier radii then they intersect but being 0, 0, 1 does not mean that they do it only means it is possible.

Craig

[dtmtim]

Thanks Craig, The solution posted there looks good but the wheels come off the cart when the perpendicular line is constructed at the mid point between the circles. The next step would be to const a pierce point using the perp line and one of the circles. At this point the math fails.

F1 =GENERIC/CIRCLE,DEPENDENT,RECT,OUT,$
NOM/XYZ,PTA2.X,PTA2.Y,-0.2697,$
MEAS/XYZ,PTA2.X,PTA2.Y,-0.2697,$
NOM/IJK,0,0,1,$
MEAS/IJK,0,0,1,$
RADIUS/0,0.1181
F2 =GENERIC/CIRCLE,DEPENDENT,RECT,OUT,$
NOM/XYZ,PTA4.X,PTA4.Y,-0.2697,$
MEAS/XYZ,PTA4.X,PTA4.Y,-0.2697,$
NOM/IJK,0,0,1,$
MEAS/IJK,0,0,1,$
RADIUS/0,0.1181
F3 =GENERIC/CIRCLE,DEPENDENT,RECT,OUT,$
NOM/XYZ,PTA1.X,PTA1.Y,-0.5453,$
MEAS/XYZ,PTA1.X,PTA1.Y,-0.5453,$
NOM/IJK,0,0,1,$
MEAS/IJK,0,0,1,$
RADIUS/0,0.1181
F4 =GENERIC/CIRCLE,DEPENDENT,RECT,OUT,$
NOM/XYZ,PTA3.X,PTA3.Y,-0.5453,$
MEAS/XYZ,PTA3.X,PTA3.Y,-0.5453,$
NOM/IJK,0,0,1,$
MEAS/IJK,0,0,1,$
RADIUS/0,0.1181
L-2 =FEAT/LINE,RECT,UNBND
THEO/-0.08534,0.08525,-0.2697,-0.0059282,-0.9999824,0
ACTL/-0.08534,0.08525,-0.2697,-0.0059282,-0.9999824,0
CONSTR/LINE,BF,2D,F1,F2,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,WAVELENGTH=0
PT-3 =FEAT/POINT,RECT
THEO/-0.08636,-0.08654,-0.2697,-0.0059282,-0.9999824,0
ACTL/-0.08566,0.03156,-0.2697,-0.0059282,-0.9999824,0
CONSTR/POINT,PIERCE,L-2,F2
L-3 =FEAT/LINE,RECT,UNBND
THEO/-0.08636,-0.08654,-0.2697,0.0059282,0.9999824,0
ACTL/-0.08636,-0.08654,-0.2697,0.0059282,0.9999824,0
CONSTR/LINE,BF,2D,F2,F1,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,WAVELENGTH=0
PT-2 =FEAT/POINT,RECT
THEO/-0.08534,0.08525,-0.2697,0.0059282,0.9999824,0
ACTL/-0.08604,-0.03285,-0.2697,0.0059282,0.9999824,0
CONSTR/POINT,PIERCE,L-3,F1
PT-4 =FEAT/POINT,RECT
THEO/-0.08585,-0.00064,-0.2697,0,0,1
ACTL/-0.08585,-0.00064,-0.2697,0,0,1
CONSTR/POINT,MID,PT-2,PT-3
L-4 =FEAT/LINE,RECT,UNBND
THEO/-0.08585,-0.00064,-0.2697,0.9999824,-0.0059284,0
ACTL/-0.08585,-0.00064,-0.2697,-0.999983,0.005823,-0.0003263
CONSTR/LINE,PRTO,L-2,PT-4,0

[craiger_ny]

Oh man, I think I steared you wrong. I see you are constructing the circles that intersect rather than they being measured. I do not know for sure but I am thinking you can not pierce a constructed circle perhaps. I do not know for sure but I know you do lose flexability with constructed features (can't intersect a constructed cylider and a plane). Maybe that is happening in your case. I'm a little stumped for a workaround right now. Perhaps more ideas will roll in. Mathematically it can be done but it is not anything I've done before.

Craig

[craiger_ny]

I'll append internet serch results here if anyone cares to run with any of them

math

more math

and some more (in case they intersect on the other side of the circle's origin)

[dtmtim]

Actually the pierce function was working. See pt-3 and pt-2 in the source code I pasted into my previous post. They both successfully pierced the constructed circles F1 and F2. I believe the problem is with the last line that was created (L-4).

L-4 =FEAT/LINE,RECT,UNBND
THEO/-0.08585,-0.00064,-0.2697,0.9999824,-0.0059284,0
ACTL/-0.08585,-0.00064,-0.2697,-0.999983,0.005823,-0.0003263
CONSTR/LINE,PRTO,L-2,PT-4,0

It looks like the normal vector goes out of wack and I think that's why I can't pierce the circle with it in the next step. I tried projecting it to fix the normal vector but it still didn't work.

t.

[Tested]

I woulds think like many features if you cast the same circle on top of these 2 circles you should be able to use pierce or drop points on them.

[craiger_ny]

This may or may not be it but can you change your naming convention to not use a minus sign. Try that and I'll look a little closer at your code too.

Also what is your workplane situation?

[cmmguy]

Craig, I thought just a simple construct intersection point - use two circles - would do this.

This is out of the manual:

You can intersect two circle features and as long as they have the same (or very
similar) vectors, PC-DMIS will generate a constructed point feature at one of the
intersection points. If you switch the order of the selected input features in the
Construct Point Mode dialog box, PC-DMIS will construct a point at the other
intersection point.

Or am I misunderstanding what is requested...

[craiger_ny]

Craig, I thought just a straight construct point - use two circles - would do this

Put it on the wish list. edit: OK that is new to me.

Looking at the code I am seeing the circles lined up in the Y axis so the vector of the last line is with the X so that seems right so I have to be missing something here.

[cmmguy]

Put it on the wish list. edit: OK that is new to me.

It was on page 727 of the manual.

[dtmtim]

I'm not sure why it won't work. The PC-DMIS error indicates that it can't figure out the math. I have this programmed in V4.0. I will try it in V3.7 to see if it used to work.

[dtmtim]

Well - after closing pc-dmis and restarting it the software finally was able to create points at the intersections of the circles. It will only work if I let pc-dmis construct a point in "auto" mode which results in a point at the midpoint. Then if I change the code manually to "INT" it will create the point where I need it. Strange ... now I have a new problem. For some reason PC-DMIS will not create a line between the 2 intersection points that I created. See my new post if you are interested.

Thanks!
t.

[Underspec]

Try this and see if it helps,

http://www.selectsmart.com/darex/cir_cir.html

[[email protected]]

Creating points at intersection of two circles

Hi need some help. I'm trying to create a points at intersection of two circles and them dimensioning the distance.