3 Basic Dimensions (3D true position)

[Big Red]

How do I report the True Position using 3 Basic Dimensions?

I have 3 Basic Dimensions and I do not know how to report the True Position for this scenario. I've always only had 2 Basic Dimensions. Shall I anticipate problems with PC-DMIS reporting correctly or is the use of 3 Basic's a normal thing?

Thanks again.

[Lee Johnson]

Not sure how to do it in PCDMIS but it is 2x the √of x²+y²+z² . I used to have a lot of items like this on some Wing struts that I used to check.

[Roberto]

How do I report the True Position using 3 Basic Dimensions?

I have 3 Basic Dimensions and I do not know how to report the True Position for this scenario. I've always only had 2 Basic Dimensions. Shall I anticipate problems with PC-DMIS reporting correctly or is the use of 3 Basic's a normal thing?

Thanks again.

Check your feature with sample hits. That way you can include X,Y and Z as part of your true position.

[Matthew D. Hoedeman]

Check your feature with sample hits. That way you can include X,Y and Z as part of your true position.

A minimum of 3 sample hits.

[Farmer]

Sounds as though you have a spherical tolerance. Its the same as with 2 basic dimensions but the 3rd one takes you into the third dimension. If you have ever seen the film Explorers then this will help you visualize it.

[kbotta]

Sounds as though you have a spherical tolerance. Its the same as with 2 basic dimensions but the 3rd one takes you into the third dimension. If you have ever seen the film Explorers then this will help you visualize it.

Right on...

[Matthew D. Hoedeman]

In days of old, before Wilcox/B&S screwed the software up, you COULD use the S axis when dimensioning a hole that had 3 or more sample hits and report the theo surface deviation at the center of the hole to help people keep straight what was what, and the TP perp to CL gave you the remaining answer to the puzzle. I am not sure if the S still works for a hole or not, I haven't tried it in a long time. Those 2 options gave you the surfaec deviation and the stab-pin answer for a hole, this was very helpful for sheet metal, probably not so much for milled parts that don't have surface variation (movement, off-nominal, whatever) that you see in sheet metal.

Doing TP with all 3 axis CAN start getting confusing real quick. You might want to report the TP-perp-cl as well, as a seperate dimension so YOU and your people can see what you actually have for 2-axis hole deviation, the perp-cl will give you a strictly 2-D look at the hole, even if it is on a 3-D surface.

[Farmer]

Right on...

Uh huh...

[Big Red]

But, but, but...

My 3 Basics are to an angled hole at the break out on it's spotface. I would measure the spotface, rotate alignment, measure the hole, project to the spotface, rotate the alignment back and then I would report. Stay with me here...

1 basic is in "X" from a plane.
1 basic is in "Y" from a plane.
1 basic is in "Z" from center of a bore.

If this is the case, do I still need 'Sample Points' as stated earlier?

Again, I bow to your expertice.

[Matthew D. Hoedeman]

YEP, you need to have the hole located EXACTLY on the part surface, and correctly orientated, so 3 sample hits, minimum, required.

[R2ah1ze1l]

Why not build an alignment based on all of your basics and report its deviation while in that "basic" alignment? would it not produce the same thing?

[dph51]

Why not build an alignment based on all of your basics and report its deviation while in that "basic" alignment? would it not produce the same thing?

Thread is over 5 years old.

[John Riggins]

Thread is over 5 years old.

Got a problem with necromancy?

[R2ah1ze1l]

Yea, stubled on this and shouldn't have bothered posting. Sorry, didn't check dates

[Jimmy Hirsch]

3 basic dimensions for a true position ?
never of heard of such a thang ........................