alignment help needed

[d.evans]

print attached.

This will probably seem awfully elementary to most of you here, but this is messing with me head.

The primary datum A is a stud cylinder.
The secondary datum B is a plane.
The tertiary datum C is a line.

I've measured all the features, now to what do I 'level', 'rotate' TO and ABOUT? and which features should I use as origins?

It seems yo me that on the drawing, that the basic dimensions are all zeroed and centered on the datum A cylinder. So it would seem to follow that I'd need to level to A and origin on A, right? but the rotate thing has me perplexed. If I level to A, and then try to use B as a rotate, then aren't those basically the same features? I mean if I make cyl A the level to Z plus, then choose B as my rotate feature, it is also a Z plus feature. Can you rotate TO Z plus ABOUT Z plus, after I've already leveled Z plus? That seems illogical. Then C is sitting down there as a Y origin feature, but none of the basic dimensions reference that line.
I am confused. help.

[#2#]

Measure A as a cylinder, B as a plane and C as a line.

Just follow the FCF. Fix as many DOF's as possible with the primary datum. Then fix as many DOF's as possible with the secondary datum. Then fix the remaining DOF's (hopefully) with the tertiary datum.

This one is going to be a little different because of the way PC-DMIS works.

Level A to z-plus (assuming back side is on the table)
Rotate C to x-plus
translate z orgin to B
translate x and y orgins to A

I know that isn't exactly as they are called in the FCF but you should always rotate before you translate.

[Matthew D. Hoedeman]

print attached.

This will probably seem awfully elementary to most of you here, but this is messing with me head.

The primary datum A is a stud cylinder.
The secondary datum B is a plane.
The tertiary datum C is a line.

I've measured all the features, now to what do I 'level', 'rotate' TO and ABOUT? and which features should I use as origins?

It seems yo me that on the drawing, that the basic dimensions are all zeroed and centered on the datum A cylinder. So it would seem to follow that I'd need to level to A and origin on A, right? but the rotate thing has me perplexed. If I level to A, and then try to use B as a rotate, then aren't those basically the same features? I mean if I make cyl A the level to Z plus, then choose B as my rotate feature, it is also a Z plus feature. Can you rotate TO Z plus ABOUT Z plus, after I've already leveled Z plus? That seems illogical. Then C is sitting down there as a Y origin feature, but none of the basic dimensions reference that line.
I am confused. help.

Looking at what you have for a print, this is what I see:

Datum A is the cylinder
Datum B is the face of the raised portion
Datum C is the flat edge of the part

I do not think this print is correct and I would 'fight' it.

Level to A datum
Rotate to C datum
Set 2 axis origin to A datum cylinder (making it 0,0), set the third to the B datum.

This is what I think they were trying to say with the print, they were just unable to do it correctly.

[d.evans]

thanks

Measure A as a cylinder, B as a plane and C as a line.

Just follow the FCF. Fix as many DOF's as possible with the primary datum. Then fix as many DOF's as possible with the secondary datum. Then fix the remaining DOF's (hopefully) with the tertiary datum.

This one is going to be a little different because of the way PC-DMIS works.

Level A to z-plus (assuming back side is on the table)
Rotate C to x-plus
translate z orgin to B
translate x and y orgins to A

I know that isn't exactly as they are called in the FCF but you should always rotate before you translate.

I actually wrote a program to measure this part a while back, and we just got some newly made parts in again that must be inspected. I always make a point to go back and check myself on how I interpreted at the time the program was written. The way you described is the way I wrote it originally, but today, I stopped and realized that the print was a little different. I appreciate all of the responses. It confirms that I was not out on a limb on this one when I originally wrote the program.

[d.evans]

Measure A as a cylinder, B as a plane and C as a line.

Just follow the FCF. Fix as many DOF's as possible with the primary datum. Then fix as many DOF's as possible with the secondary datum. Then fix the remaining DOF's (hopefully) with the tertiary datum.

This one is going to be a little different because of the way PC-DMIS works.

Level A to z-plus (assuming back side is on the table)
Rotate C to x-plus
translate z orgin to B
translate x and y orgins to A

I know that isn't exactly as they are called in the FCF but you should always rotate before you translate.

what is a DOF?

[#2#]

Degree Of Freedom.

3 rotational and 3 translational = 6 total

[d.evans]

Degree Of Freedom.

3 rotational and 3 translational = 6 total

DOH!!!!

thankyaverymuch.

[#2#]

DOH!!!!

thankyaverymuch.

No, DOH belongs in the beer thread.

Degree
Of
Hammeredness

There are only four of those:

Hammered
Not Hammered
Hammered but claims to be Not Hammered
Not Hammered but claims to be Hammered