Could someone please explain what the "SNAP" feature under measurement properties in the Auto Feature dialgog box means and when it would be used? Thanks in advance!
All that snap does is put the actual measured point on the nominal vector of the point. Think of it THIS way:
Nominal XYZ along with the nominal IJK will make a 3-D line in space that goes on forever. Now, you measure a point. That point exists in 3D space. Now, make a plane, perpendicular to that 3-D line that goes through the actual measure point. SNAP=ON will give you the point where that 3D line instersects that plane. That's all it does.
SNAP has no effect at all on the "T" axis of a point, it will be exactly the same, ON or OFF.
If you have a point @ X0, Y0, Z0, with a vector of 0,0,1......
NO machine is perfect, ALL machines have SOME amount of drift.
So, that point @ 0,0,0,0,0,1 won't actually get measured at X0Y0, but at some 'real close' location, perhaps X0.011, Y-0.009, and Z 0.351. In either case (ON or OFF) the T axis will report +0.351. However, with SNAP=ON, the report will show it checked at X0 Y0 not at X0.011 Y-0.009. But the "T" is the same, no matter ON/OFF. So, it will also have no effect on 'profile' since 'profile' is based on the "T" axis deviations.
Never use SNAP=ON when doing an ITERATIVE alignment, don't do it, never, not at all, since the TARGET diameter is part of the iterative alignment, using SNAP=ON will screw it up.
You can check a point with SNAP=ON, then you can turn it back off, without re-measuring the point, and you can then see how much drift your machine has. And, it will be different for each and every possible check direction you can think of. the drift will not be the same for vectors of 0,0,1, 0,1,0, 1,0,0, .7071,.7071,0, etc., etc., etc.
All that snap does is put the actual measured point on the nominal vector of the point. Think of it THIS way:
Nominal XYZ along with the nominal IJK will make a 3-D line in space that goes on forever. Now, you measure a point. That point exists in 3D space. Now, make a plane, perpendicular to that 3-D line that goes through the actual measure point. SNAP=ON will give you the point where that 3D line instersects that plane. That's all it does.
SNAP has no effect at all on the "T" axis of a point, it will be exactly the same, ON or OFF.
If you have a point @ X0, Y0, Z0, with a vector of 0,0,1......
NO machine is perfect, ALL machines have SOME amount of drift.
So, that point @ 0,0,0,0,0,1 won't actually get measured at X0Y0, but at some 'real close' location, perhaps X0.011, Y-0.009, and Z 0.351. In either case (ON or OFF) the T axis will report +0.351. However, with SNAP=ON, the report will show it checked at X0 Y0 not at X0.011 Y-0.009. But the "T" is the same, no matter ON/OFF. So, it will also have no effect on 'profile' since 'profile' is based on the "T" axis deviations.
Never use SNAP=ON when doing an ITERATIVE alignment, don't do it, never, not at all, since the TARGET diameter is part of the iterative alignment, using SNAP=ON will screw it up.
You can check a point with SNAP=ON, then you can turn it back off, without re-measuring the point, and you can then see how much drift your machine has. And, it will be different for each and every possible check direction you can think of. the drift will not be the same for vectors of 0,0,1, 0,1,0, 1,0,0, .7071,.7071,0, etc., etc., etc.
