Vector Deviation

[J Temmen]

I have recently discovered something and I can't explain and even worst my customer has noticed it and would like an explaination.

v3.7mr3, CAD++, BnS Xcel 12-20-10

If I take a sample surface measurement and then reference that point when doing a vector or surface point on the edge the "T" deviation is not the sqrt of the sum of the squares, it appears to add the surface deviation from the RMEAS point into the calculation. My question is how do you report the edge normal deviation on a point that requires an RMEAS.

[Matthew D. Hoedeman]

http://cmmprogrammer.19.forumer.com/viewtopic.php?t=99

This will answer your questions.

[#2#]

It doesn't happen to be double the sqrt of the sum of the squares does it?

Nevermind, Matt knows what is going on.

[J Temmen]

Matt,

I am unable to use edge points, I have to use seperate vector/surface points.

[Matthew D. Hoedeman]

Why can you not use edge points? They work great. Even if the edge you are measuring is NOT square to the surface, you can still use them.

1) Find the vector for the edge you want to check using vector point
2) Change to edge point, click where you want to measure the edge on the top surface
3) TYPE in the vector from step 1 for the edge vector

If you can't do this either, then you are in for a LOT of fun. You will have to construct nominal points on the surface.

1) COnstruct a point at ORIGIN
2) Construct OFFSET points from the ORIGIN point
3) Construct a plane from those points
4) Project the measured point into the plane

This will remove the surface deviation, but the angle of projection will probably still be a problem. You may have to construct an offset point, PERPENDICULAR to the edge vector, construct a line, then instersect the line with the constructed plane.

[J Temmen]

A simple "I don't know" would have worked.

[Matthew D. Hoedeman]

A simple "I don't know" would have worked.

Well, gee, "I DON'T KNOW".

Why can't you use EDGE POINTS? Do you NOT have the functionality? IF you have it, use it. Problem solved if you use GAP ONLY MODE. You never answered this question. WHY can't you use EDGE POINT?

I have recently discovered something and I can't explain and even worst my customer has noticed it and would like an explaination.

v3.7mr3, CAD++, BnS Xcel 12-20-10

If I take a sample surface measurement and then reference that point when doing a vector or surface point on the edge the "T" deviation is not the sqrt of the sum of the squares, it appears to add the surface deviation from the RMEAS point into the calculation. My question is how do you report the edge normal deviation on a point that requires an RMEAS.

Are you using SNAP POINT when measuring that point on the edge, the one that is REFERENCED to the top surface? If not, try turing it ON, SNAP POINT will put the vector point BACK ONTO the nominal vector line.

[J Temmen]

The original question had to do with the use of vector/surface points not EDGE points, if I had a question on EDGE points I would have asked that. We use vector/surface points based on what our customer requirements are. Now with that being said, does anyone now how the "T" deviation on a vector/surface point is calculated when you RMEAS another point, it's not the sqrt of the sum of the squares.

[Matthew D. Hoedeman]

The original question had to do with the use of vector/surface points not EDGE points, if I had a question on EDGE points I would have asked that. We use vector/surface points based on what our customer requirements are. Now with that being said, does anyone now how the "T" deviation on a vector/surface point is calculated when you RMEAS another point, it's not the sqrt of the sum of the squares.

WELL, once again, ARE YOU USING SNAP POINTS or NOT to do this RMEAS? This could very well be what solves YOUR issue.

What you are doing, by using a SURFACE SAMPLE, then referencing THAT point on the edge IS EXACTLY WHAT AN EDGE POINT IS, that is WHAT IT DOES.

BUT, since you refuse to answer OUR questions, whyinthehell should we try to answer yours?

I have asked a few questions, but no replies from you. I would guess that OTHERS are also waiting for those same answers since those answers MIGHT be the solution to YOUR problem.

IF YOU are using SNAP POINTS for the VECTOR point, it should be snapping the actual BACK ON TO the nominal vector line of the part, thus giving you sqrt(xdev^2+ydev^2+zdev^2)=T. But, we don't know if you are using it, you won't answer. HERE are the SNAP POINT issues, INCLUDING THE T VALUE CALCULATION OPTIONS.

http://cmmprogrammer.19.forumer.com/viewtopic.php?t=98

The option for NON-SNAP POINTS should be the answer you are looking for, HOWEVER, when asking for HELP and those of us TRYING TO HELP YOU ask for information, YOU SHOULD GIVE US THAT INFORMATION.

[bw_bob]

[craiger_ny]

http://www.fstdt.com/funnyimages/uploads/169.JPG

[bw_bob]

But who is wh......never mind

[Peter Warcholyk]

Mathew,

As you have stated, edge points would be the best thing to use.

I have to report out "trim lines" on many a plastic part.
I measure these using edge points, and report out the "s" component for the surface, and the "t" component for the edge.
This works out fine for me.

I don't know why the gentleman insists on using either vector or surface points.

ZydecoPete

[cmmguy]

I'm just glad it's not me this time....

[Matthew D. Hoedeman]

Mathew,

As you have stated, edge points would be the best thing to use.

I have to report out "trim lines" on many a plastic part.
I measure these using edge points, and report out the "s" component for the surface, and the "t" component for the edge.
This works out fine for me.

I don't know why the gentleman insists on using either vector or surface points.

ZydecoPete

Exactly the way I check sheet metal parts. The only time I do NOT use the "S" and DO USE the GAPONLY mode is when the trim edge is a radius parallel to the edge itself. Pcdmis only know the surface vector AT THE EXACT edge, it will not 'find' the nominal and vector for the indent you set up, so in that case, I will watch it, see what I need for the depth, then set it to gap only. If I also need surface data there, I will add a vector point.