Do away with manual alignments - use Readpoint

OK looks like I got some practicing to do....thanks for all the input guys.

One more question...why does my readpoint show up way away from my actual stylus on the graphics window? Isn't supposed to show up right where the ruby is?

It is likely because the machine has not been told where the part is in relation to the machine volume. Are you starting this program from scratch or trying to add a readpoint to an existing program? If it's an existing program, first try clicking past your finished alignment and see if everything snaps to where you expect it. Or you may need to execute to get it all looking "right" in your graphics window. When I run a part in a different location in the CMM volume than I had it the last time I get features that "float" in space off the cad model until they actually get measured. I can watch them snap to the cad as the program runs.

Starting a new program. It looks like it's doing what you said, and is going in the right area now.

hey gomo why do you have you x and y axis offset to the original but with - in front of it, (in your first alignment) A1???

The part origin is at the lower left in a top view which leaves all features with a positive X-Y coordinate value. The alignment translates first to the readpoint then offsets the X & Y back to the origin. Just a personal preference. For me it's always better to work in the model axis system which makes it easier to interrogate the cad (we use Catia which has a few more tools than PcDmis). Once I have my final alignment I like to verify a few features with a second opinion. More than once I botched the datum alignment and ended up loosing a lot of programming time. Another way would be to record some temporary auto features before any alignment and then pick the same features again after the alignment - the locations should match.

As for a readpoint - just think of it as a measured feature without having to touch anything. Not quite as accurate but it gets the ball rolling. You should be able to drop the code I gave earlier into a new program and import the cad to see it run. On my system the file is at C:\Users\Public\Documents\WAI\PC-DMIS\2014.1\CAD\HEXBLOCK.CAD. Running it offline may give you a better feel if you don't have the physical demo part on hand. Once you use it a few times it will become second nature. Most of what I use readpoint for sits flat on the table but I've also done a 3D bestfit using 3 points (non-coincident, non-colinear).

I'm going to have to drop that into a new program and try that. Thanks for the tip.

I want to thank everyone that helped me with this readpoint alignment business. With a little work and tweaking, it works fantastically. I did a rough dcc alignment after the readpoint in places that I knew I could refer back to my datum targets, and then did my actual full on dcc alignment using my datums targets, and it worked from start to finish flawlessly.

And I never took a single manual hit. just put the tip where the comment said, and hit execute. Presto. It ran through the rough dcc, then went to the datum dcc, and the my alignment is right where the center lines on my print intersect. Even when I zoom in really really close my trihedron is right on the money.

Thanks soo much guys. I think I will be working with this much much more, with parts that are on fixed fixtures.

Those are the discovery moments that keep me going. It's great to sit down and work out how it all needs to go together and first getting it to run and then getting it to run and report right. I'm in the middle of trying to dial in equating an alignment. I can get it all working right, and my simplified test passed with flying colors, but for some reason my true position results are a little suspect on the features that are measured after I move the part....I feel like I'm close tho!

My DCC alignment, which uses the datum targets, seem to have fell right into place perfectly. And so far I have created two diameters using auto circle, and they seem to be right where they need to be.

I really like this.