begineer still struggling with the basics

[joes64]

hi there,
When doing 321 alignment and looking at the cad graphics on screen i often find one axis arrow pointing the wrong way .I am trying to get the axis relative to the way the part is siting on the cmm table . Usually Y plus is pointing in the Y minus direction sometimes its Z plus pointing Z minus. when i try to fix this, it always alters the other axis as well . What am i doin wrong

[Darin Steiner]

Don't use 321 alignment. I never us it for that very reason. For example, if lining up a surface that has a normal vector of 1,0,0 you would want to level to X+ plane, and if you had a line with a normal vector of 0,-1,0 you would want to rotate to Y- about X+. In other words, align your datum feature positive & negative vectors to the positive & negative machine axis. Pay attention to your alignment feature vectors.

[Wes Cisco]

I use almost nothing but 3-2-1 alignments. However if you are trying to match you CAD trihedron to the way the part is aligned on the machine you may need to manipulate the CAD itself. The previous advice about paying strict attention to vectors is spot on. If you can set the part on the table and "see" the alignment as it is on the CAD, then you will not need to manipulate. I would go into how to manipulate but I don't know which version you are using and if you are using 4.x it is supposed to be easier but I am sticking with 3.7MR3 for the time being. HTH

P.S. Don't give up. This stuff can be done. Oh, and start drinking heavily!

[Matthew D. Hoedeman]

Or, just as easy (even easier, really) you can do the CAD to MACHINE setup, in F5.

1) Rotate the cad data, using the 3-D rotate until the cad matches the way YOU have the part setup on the table and leave the 3-D rotate window open
2) Hit <F5>
3) Go to Part/Machine
4) Look at the 3-D rotate icon and see which way the cad axis are pointing.
5) Make the PART SETUP axis match, tell it that the cad X+ axis matches the machine Y- axis, etc.
6) Set the correct workplane (probably one of the biggest problems you are having)
6) Now, leaving the 3-D window open, measure the alignment features, then do the 3-2-1 alignment.

It is a WHOLE lot easier than it sounds and if you are required to report the results to the CAD position in the file you were sent, then you CAN NOT manipulate the cad data orientation or origin, you must work with what you have (99% of automotive requires all data to be in CAR POSITION).

Once you have done it a few times, AND depending on how well YOU can visualize 3-D space (the better, the easier it will be), it will get to be second nature in no time at all. I don;t even have to think about it any more, just BANG! BANG! BANG! BANG! and it's done, and in less time than just about anyone can manipulate the cad data, even in Pcdmis!

(sounds like a gang-bang, don't it?)

[joes64]

I use almost nothing but 3-2-1 alignments. However if you are trying to match you CAD trihedron to the way the part is aligned on the machine you may need to manipulate the CAD itself. The previous advice about paying strict attention to vectors is spot on. If you can set the part on the table and "see" the alignment as it is on the CAD, then you will not need to manipulate. I would go into how to manipulate but I don't know which version you are using and if you are using 4.x it is supposed to be easier but I am sticking with 3.7MR3 for the time being. HTH

P.S. Don't give up. This stuff can be done. Oh, and start drinking heavily!

hi, im using v 4.1 can you give me some more info about vectors .... Im not grasping wot ur getting at ....bear with me .......

[rangerboat72]

hi, im using v 4.1 can you give me some more info about vectors .... Im not grasping wot ur getting at ....bear with me .......

I'd recommend looking @ this site: http://www.manufacturingcenter.com/t...03qmvector.asp

It gives a pretty decent explanation (probably better than I could explain them to you).

[Wes Cisco]

hi, im using v 4.1 can you give me some more info about vectors .... Im not grasping wot ur getting at ....bear with me .......

If Rangerboat's link does not help you, send me a PM or post here again and I will take a shot at explaining vectors to you. You must understand them to use pc-dmis well. Have you had any of the B&S classes?

[joes64]

If Rangerboat's link does not help you, send me a PM or post here again and I will take a shot at explaining vectors to you. You must understand them to use pc-dmis well. Have you had any of the B&S classes?

I have a basic understanding of vectors but I am not understanding how they are affecting alignment direction with 321 alignment .

[Matthew D. Hoedeman]

If you rotate your X+ axis to a line, then the X+ direction will point ALONG the vector of the line. It will not point backwards. If you measure the line with 2 hits, the first hit on the left side and the second on the right side, then the X+ axis will point from left to right. IF the first hit for the line is on the right and the second on the left, then X+ will point from right to left.

[Wes Cisco]

3 = plane
2 = line
1 = point

In it's simplest form. Now does your line "point"(vector 1,0,0) left or right? If it points right and you rotate X+ to it then you would have the alignment I use most often, but if your line "points"(vector -1,0,0) to the left and you rotate X+ to it you have "flipped" two axis of the alignment!!!

Maybe you should put a 1-2-3 block on the table and measure a plane a line and a circle then experiment with different alignment options while watching the graphics window from at least two viewpoints. Then you will be able to see how vectors effect alignment. HTH