How to calculate the Y PLUS rotation angle about X PLUS?

Hello all.

I tried to read an old program, and got lost about -1.91 rotation angle. Anyone could explain to me how to calculate it?

The stud is Datum B, the round slot is datum C, A1 plane around B is 7 mm high than A2 around C. The program starts with 2 readpoints: PTR_B and PRT_C. I could calculate the first rotation angle 11.508 degree, which is around arctan(30.54/150.096). Then I thought the second angle should be arctan(7/150), around 2.58 degree, but it was not right and -1.91 was perfect. My question is how to calculate it? One more thing, there was -0.425 offset on Y axis when construct the PNT_PTRB_OFF, Where it comes from?

Thank you for any help , clue...

0 louisd 7 months ago

Considering Cir_B has non-normal vectors, the -1.91 might still be "perfect" because you didn't square up the features (after the alignment) to the mathematically correct angle.

I'd try replicating the original routine to test (without screwing up existing one) rotate about the angles you've deemed correct then see if the cad for later features (like CIR_B) aligns to your normal vectors.

In my opinion readpoints like that are a waste. Your actual readpoint online (when executing) will never be accurate enough for those to reproduce. You're much better off doing ONE readpoint to find the part, align xyz then immediately start probing datums/aligning to each.
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0 RobOntario 7 months ago in reply to louisd

Cir_B and C both are normal vectors, should be 0,0,1. I do not know why he did not care about it. :(
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0 RobOntario 7 months ago in reply to louisd

I believe after one rotate, the angle was squeezed, wonder how to calculate it ..
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