vector question

[Rob Knoerlein]

In relation to my post a few posts down........Rob Knoerlein-circular part with 8 legs.. If I am rotated 90/135 and tracking to hit a feature ( in this case a leg), that is at approximately 2:00 , would not my vector be -.7071,-.7071,0 ? The whole part is programmed in z plus but I thought vectors are directionals of the probe coming off the feature???? This is what they taught at training???The probe is tracking towards the leg but seems take to point at the last minute by sweeping left to right and not just taking it head on. Someone suggested my workplane was incorrect but I have always pretty much stayed in Zplus when working with large diameter rings. I admit I usually am using cad and the machine picks the vectors, but Im still unsure why changing these do not get me good hits???

[pniven]

If you are taking a circle from the z+ work plane the the circle vector will be 0,0,1 z+
The points it is takeing around the circle to get that center location will each have different vectors. the angle of the tip will not change the approach vectors to those points. The vector for the tip only helps define the angle and direction of the tip and nothing more. I hope I said this so you understand it.

[JamesMannes]

In relation to my post a few posts down........Rob Knoerlein-circular part with 8 legs.. If I am rotated 90/135 and tracking to hit a feature ( in this case a leg), that is at approximately 2:00 , would not my vector be -.7071,-.7071,0 ? The whole part is programmed in z plus but I thought vectors are directionals of the probe coming off the feature???? This is what they taught at training???The probe is tracking towards the leg but seems take to point at the last minute by sweeping left to right and not just taking it head on. Someone suggested my workplane was incorrect but I have always pretty much stayed in Zplus when working with large diameter rings. I admit I usually am using cad and the machine picks the vectors, but Im still unsure why changing these do not get me good hits???

Are you using learned hits vs auto-vector points? If so, then what you are seeing is why most people don't use measured hits. If you try to vector in ona surface other than a straight on vector, DMIS interprets your hit as straight on. Try the same thing with an auto-vector point and se what happens.

[cmmguy]

The vector for the hits at the 45's should be 0.7071... each. The sign should be negative for both when the hit is halfway between X+ and Y+.

So yes, your vectors are correct (as long as this is an ID)

[Pat Ahern]

In relation to my post a few posts down........Rob Knoerlein-circular part with 8 legs.. If I am rotated 90/135 and tracking to hit a feature ( in this case a leg), that is at approximately 2:00 , would not my vector be -.7071,-.7071,0 ? The whole part is programmed in z plus but I thought vectors are directionals of the probe coming off the feature???? This is what they taught at training???The probe is tracking towards the leg but seems take to point at the last minute by sweeping left to right and not just taking it head on. Someone suggested my workplane was incorrect but I have always pretty much stayed in Zplus when working with large diameter rings. I admit I usually am using cad and the machine picks the vectors, but Im still unsure why changing these do not get me good hits???

No. Rotate +45 degrees from Y+ (1:30/2:00 o'clock) would be +.7071,+.7071,0. Vectors always point away from the surface.

Comments anyone

[Pat Ahern]

Sorry, I assumed outside dia of ring. If measuring the inside, the -.7071,-.7071,0 is correct. But why does your vector on the other thread read 0,-1,0?

[Rob Knoerlein]

That was before I changed them...After changing, the probe crashes into the wall so the issue really isn't resolved yet.

[Rob Knoerlein]

And yes, I am going completely insane. What I ended up doing yesterday was to simply clock the part 1/8 a turn so the hits checked the other four legs straight on. I was able to get the part out the door on time and felt comfortable with it, but while lying in bed last night, the reality that I almost had the guys skim .010 off the inner diameter of a $40,000 dollar part made me almost throw up. No wonder I have sleep apnea. I am going to work on this today time permitting as I really need to get it for future jobs. Im wondering now if this circular tracking probe vector stuff is not what was causing all the trouble I had sometime back with wacked out TP measures using polar angle and polar radius to calculate???

[vpt.se]

What version of PC-DMIS do you have?

I know some version had a bug affecting TP with polar angle and radius...

[Rob Knoerlein]

4.2..................................could This Possibly Be The Answer??????????????

[cmmguy]

Can you post this code section?

[djayne]

There's no bug - your point vector directions are according to your part alignment. The only way your vectors should be .7071 is if you are taking a point 45° to one of your datum planes.

[pniven]

Are you using learned hits vs auto-vector points? If so, then what you are seeing is why most people don't use measured hits. If you try to vector in ona surface other than a straight on vector, DMIS interprets your hit as straight on. Try the same thing with an auto-vector point and se what happens.

James gave you a good answer. Use your Auto vector point, it should work.

[pniven]

there's No Bug - Your Point Vector Directions Are According To Your Part Alignment. The Only Way Your Vectors Should Be .7071 Is If You Are Taking A Point 45° To One Of Your Datum Planes.

++1

[vpt.se]

4.2..................................could This Possibly Be The Answer??????????????

MR1? If not, you should really think about getting that installed.

If I'm not wrong, the PAng/PRad TP bug affected features not measured while in Z+ workplane. If the features you have are measured in Z+, then you should check your alignment again, to see that it is correct.

But then again, this might not be related either...