Alignment Rotation Question

I would think that you could measure a line on each side of the slot and then construct a mid line. then i would rotate to the mid line. If you rotate from the center of -A- you will not get accurate results as to where the actual location of the slot would be.

William, yes, that is the default approach. However, I'm concerned that this slot is a little too short to use as a sole rotation feature. Any slight measurement inaccuracy, for example, and the rotation of my coordinate system will be off. I think my program would be slightly more repeatable if I somehow connected the slot with the OD. Do you agree? I might be wrong on this, but this is the general approach I have taken over the years.

William, yes, that is the default approach. However, I'm concerned that this slot is a little too short to use as a sole rotation feature. Any slight measurement inaccuracy, for example, and the rotation of my coordinate system will be off. I think my program would be slightly more repeatable if I somehow connected the slot with the OD. Do you agree? I might be wrong on this, but this is the general approach I have taken over the years.

You need to make sure that the lines that you use for the midline are aligned to prior to measuring the lines. This way you ensure that the points taken are always in the same location on every part based on the actual location that they are at.

so I would measure those lines 2x aligning on the 1st ones and using the 2nd ones for midline construction and rotation.

yes it is a short line but it is all you have to use. You could also build a hard gage to check it.

also I want to add that your measurement might be more repeatable but it will be inaccurate.

You could also try to use 2 planes with a mid plane. That might help.

I agree, it would be inaccurate per the print. However, do you agree that most parts like this would actually assemble to a connection line? For example, lets say the OD would rest on a mating part, then the part would rotate relative to the both the OD and the slot.

Not sure how your assembly works. Lets say that you have a drive shaft with a break away key slot. if the slot is too far off center it will not work. you need to have the sides of the slot parallel to the center line of the shaft.

think of a trapazoid affect.