Vector pnt -vs- Surface pnts Pros_&_Cons

[Paul Sarrach PC-DMIS Guru Find all posts View Profile Close Paul Sarrach]

Just curious, What do you prefer Vector points or surface points, and the pros and cons to them. Seems Vector points seem to have a lot of flaws. I personally always use surface.

[Matthew D. Hoedeman has received PC-DMIS total consciousness Find all posts View Profile Close Matthew D. Hoedeman]

The main difference between the 2 is that surface points allow sample hits so that Pcdmis can calculate the actual vector for the point, then drive on that vector instead of the cad nominal vector. Unless you have a part that is really whacked out of shape OR tolerances too close to even think about, vector points work just fine. Using a 2mm ball probe, if the surface is 10 degrees off angle to cad, you will see 0.015mm or error due to the surface being at teh incorrect error. That is about 0.0005", not enough to worry about for automotive sheet metal, but it might be enough for some other applications. But then again, if the part is that critical, that off-angleness whould show up with any other check you make and thus give you a bad part anyway. Also, by using surface points with sample hits, you would need a minimum of 3 to calculate the vector, so now you are taking 4 hits for 1 data point, multiplying your run time by a factor of 4. What 'flaws' are you talking about with the vector points? I have never seen any.

[ag162 Ultra Senior Member Find all posts View Profile Close ag162]

Personally, I prefer vector points on a contoured surface or small radius, if i have cad and am checking a gauge. For less countoured or angled surfaces, then surface points are the best option.


A.Gore

[Johnson Member Find all posts View Profile Close Johnson]

agree with Matt

I use vector points versus surface points. Some programs already have 2000 plus hits on them. I don't need anymore run time. Would like to know if I am missing something on the negative of using vector points. When I am using them I usually have a profile tolerance of 1.2mm.

[Paul Sarrach PC-DMIS Guru Find all posts View Profile Close Paul Sarrach]

Well in the old versions I remember haveing to make sure the vectors were correct so that they would compensate for the ball correctly. I remember haveing trouble when editing those points, And getting incorrect values, dont know if they change that in the newer versions? But I have used surface points ever since. Also I never get the wrong approach vectors either.

I do lean inspection. There is not a lot of points. I do not use pre-hits much at all. I just been talking to some of the guys and could not give them a good explaination to the difference. Just my preference.

So why have vector points at all if the only difference is the option of pre-hits. So a Surface point is a Vector Point if you dont use Pre-hits?

[george frick Senior Member Find all posts View Profile Close george frick]

most of the parts i measure have nice flat precision machined surfaces so i go with vector points. if i was measuring sheet metal with deformed or bent surfaces i would go with surface points to calculate the actual surface normal vector.

[Jeffrey Lovely Senior Member Find all posts View Profile Close Jeffrey Lovely]

You can use RMEAS with surface pnts
cant with vector point
never tried in the edit widow - may be possible ?

[John Kingston PC-DMIS Guru Find all posts View Profile Close John Kingston]

I use vector points. Most of what I use the cmm for is machined parts, so no biggie... also because I do a lot of cone measurements and can't use the same tip. So I copy and paste with pattern. Works great.

(OOO! This is #99!)

[Boom Boom Junior Member Find all posts View Profile Close Boom Boom]

I use Vector points, very rarely Surface points. I work with a lot of prototype parts and need to write programs and inspect components very quickly.

Dave

[rebeldude Senior Member Find all posts View Profile Close rebeldude]

I always use vector points to do the algnment on the fixture and surface points for the sheet metal part. I have found that to work the best for me.

[kbotta Ultra Senior Member Find all posts View Profile Close kbotta]

I rarely use s.pts (unless surface is way off), I use v.pts almost always.

[Paul Sarrach PC-DMIS Guru Find all posts View Profile Close Paul Sarrach]

Kevin, looks like you had a powdered doughnut with your coffee this morning. And you look way different without your glasses. Its funny how glasses can make the man.

[Wes Cisco PC-DMIS Guru Find all posts View Profile Close Wes Cisco]

Can Don (trytohelp) weigh in here?

I was under the impression that aside from the surface hit option, the main difference was that vector points would handle angle hits better. That is, if my vector is straight on in any direction (0,0,1/1,0,0/0,1,0/etc) I use a surface point, but if it will be an angle, (0,.707106,.707106/.5,0,.8660254/etc) then I use vector point. On several occasions I have inadvertantly used a surface point when I meant to use a vector, (by the above rationale) and vice versa. I have never noticed it making any difference what so ever. So why are there both, if a vector point is just a surface point w/o surface hits? If you use surface point without taking any sample hits, how does that differ from using a vector point? Is this just an easy way to claim another "exciting feature" of the software?

[R. Farr Member Find all posts View Profile Close R. Farr]

I use surface points only when I have to.

I RMEAS our flush and margin points, so that's when we'd use surface points.

The only other time I can think of is if I need to sample around a hole, but there isnt' enough room for 3 initial/perm hits, I'll pick a surface point near the hole and obtain the vector that way.

[george frick Senior Member Find all posts View Profile Close george frick]

kevin

Kevin, looks like you had a powdered doughnut with your coffee this morning. And you look way different without your glasses. Its funny how glasses can make the man.

looks like kevin did a "got milk" commercial