Iterative alignment and using XactMeasure

Alright here is my problem/question.
I have a part where Datum -A- (Z axis) is not prismatic, however datum -B- (X axis) and -C- (Y axis) are.

I do not have much experience with Iterative alignments other than that I have been to the Level 2 Hexagon class (Just don't use them or have the need too).

My thoughts were, this is a good time, to try an Iterative alignment.
I believe I have that part of the program correct:
I created 6 auto vector points on top (Datum -A-),
then 5 auto vector points on left side (Datum -B-)
then finally 5 auto vector points on the front of the part (Datum -C-).

When I create the Iterative alignment I pick top 6 points as level (Datum -A-),
5 points on left rotate (Datum -B-),
then 5 points on front as origin (Datum -C-).

After completing this Iterative alignment my trihedron doesn't move from before the alignment.
So I constructed planes out of the five points for datum -B- and -C- respectively.
I then origin my "X" to Datum -B- and my "Y" to datum -C-.
How do I origin my "Z", and how do I assign my datum -A- for exact measure? Where did I go wrong? Please any help would be greatly appreciated.

Parents

BWIZZLE over 9 years ago

How can you report out from datum A when it's not a prismatic feature? Where about on this irregular feature do you want your zero/origin to be exactly?

Iterative is the only way to align a part like this.

Now once you've aligned using iterative you could translate your origin by a given value so the zero moves where you want it. i.e. if your two holes are perpendicular to datum A (or should I say they are square to the axis controlled by Datum A) then you could move it by the theo values of datum B so you're origined over this hole, but how much you move it up or down to the datum A surface is anyone's guess!

Not sure if that's clear, but it would be like aligning to the corner of a 1-2-3- block, then measuring a hole and reporting the deviations. Your nominals would come from the corner.

You could then offset the alignment by the nominal values so the hole's theoretical location would be 0,0. If you report the location again the deviations would be identical, but the Noms would be 0,0. The edges you aligned to are still the datums (i.e. They are right/have zero deviation) even though their nominal values are no longer zero!

Yes, this was my original question/problem. How do you translate (origin) to my datum "A" for the Iterative alignment (if you can't determine the value), or define this irregular shape for Exactmeasure so that my dimensions for my true positions are the basic dimensions from the print. This is what my customer wants, and since the customer is always right, I came here for advice. It seems a lot of people want to give me answers not totally understanding what i'm up against. Maybe people jumped in before reading everything on this thread, I don't know. What I've done (I've stated this in a prior post) is put three auto vector points on approximately the three high spots of datum "A" (like if you set it down on a datum simulator surface i.e.surface plate) then constructed a plane out of those three points. Called that plane datum "A" and measured it in Exactmeasure. Voila, I didn't have to use an Iterative alignment, because that wouldn't work for my situation. I understand everything everyone is telling me, and I really do appreciate that,(except the few people that want to criticize and belittle people) I just don't think they understand what I'm telling them or trying to explain to them.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel

Reply

BWIZZLE over 9 years ago

How can you report out from datum A when it's not a prismatic feature? Where about on this irregular feature do you want your zero/origin to be exactly?

Iterative is the only way to align a part like this.

Now once you've aligned using iterative you could translate your origin by a given value so the zero moves where you want it. i.e. if your two holes are perpendicular to datum A (or should I say they are square to the axis controlled by Datum A) then you could move it by the theo values of datum B so you're origined over this hole, but how much you move it up or down to the datum A surface is anyone's guess!

Not sure if that's clear, but it would be like aligning to the corner of a 1-2-3- block, then measuring a hole and reporting the deviations. Your nominals would come from the corner.

You could then offset the alignment by the nominal values so the hole's theoretical location would be 0,0. If you report the location again the deviations would be identical, but the Noms would be 0,0. The edges you aligned to are still the datums (i.e. They are right/have zero deviation) even though their nominal values are no longer zero!

Yes, this was my original question/problem. How do you translate (origin) to my datum "A" for the Iterative alignment (if you can't determine the value), or define this irregular shape for Exactmeasure so that my dimensions for my true positions are the basic dimensions from the print. This is what my customer wants, and since the customer is always right, I came here for advice. It seems a lot of people want to give me answers not totally understanding what i'm up against. Maybe people jumped in before reading everything on this thread, I don't know. What I've done (I've stated this in a prior post) is put three auto vector points on approximately the three high spots of datum "A" (like if you set it down on a datum simulator surface i.e.surface plate) then constructed a plane out of those three points. Called that plane datum "A" and measured it in Exactmeasure. Voila, I didn't have to use an Iterative alignment, because that wouldn't work for my situation. I understand everything everyone is telling me, and I really do appreciate that,(except the few people that want to criticize and belittle people) I just don't think they understand what I'm telling them or trying to explain to them.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel

Children

No Data