clearance data vs. cmm positioning

[[Me...]]

I noticed in an older program that I did not do clearance data was used instead of cmm positions. This was to jump a clamp in creating a line. Seemed interesting. Seemed quicker.
Would you use it this way? Pros and cons.

[[Ia...]]

Pros - Faster, cleaner, exact

Cons - Takes much more time to set up

I typically use cmm positions when I have to do like a -Y,+Z,+Y clearance moves in one feature back to back to back. Not only is it faster, but sometimes the CMM will do some wonky moves that doesn't make sense when stacking clearance moves (at least in my experience). I also suggest CMM positions if you're changing an RDS angle in between measuring strategies for a single feature. It's also helpful when measuring the counter-bore diameter, depth, and hole diameter. Just a lot cleaner/faster.

Also, if you didn't know, you can change the exact x,y,z of the cmm position in the strategy window as well. Helpful when you want to position right in the center of a hole.

[[Me...]]

We have an XXT RDS so when it comes to complex angles and movement there is no getting around using Position Points, it just takes a bit longer like Ian said.

[[Ri...]]

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On your note about measuring the counterbore diameter, depth, and hole diameter, have you ever used sub-clearance planes? It's great for this purpose.

Position points are great if you don't ever plan on changing the program. Clearance Planes are easier as the program shrinks, and grows.

[[Cl...]]

This approach always fascinated me. I remember a Zeiss applications engineer years ago told me
that in his programs he would place a position point centered above the part for all the probe rotations.

[[Me...]]

Thanks all.
I'll stick with the position points for now.
I don't get into too many complicated positioning issues.
If I have to add a lot of position points I'll do my trick of inverting the clearance distance value with the retract distance and just jump around.

[[Me...]]

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I use them for "eyeball" alignments, extremely useful. Like say you have a hole of a bolt pattern that is on center that you may use to align for the Base Alignment. I create a position point above the part slightly and "X" or "Y" location, I put in a programmable stop referring to align the hole to the probe and then we're cooking with gasoline.

Your part would need to be able to rotate about Z in the fixture before you clamp it down with this method though.

[[Ia...]]

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I agree with you, (sub)clearance planes are for sure more future proof.

Sub clearance planes are something I need to read more on. The way I do them, it normally takes longer than just creating cmm position points. There's probably a better way, and I just don't know it yet.

[[Ro...]]

Over the years i've started trusting Calypso to move around by itself.
Clearance moves and Block edges is usually all i need to safely get around fixtures and 'up & over' my workpiece.
Don't get me wrong, some of my older programs have very detailed XY&Z moves.
Now usually the most ill do to be safe is to combine clearance moves to get the head moving in a safe direction, like going +X then +Z before the next feature which is going to be -X clearance.
But i have an XT so i don't have to deal with articulation.

Additionally the programs i work with in our Detroit facility use XXT, and those programs always jet up in +Z before the head spins, for those programs that keeps everything safe.

Additionally2, if you have cad models of your fixtures, that helps tremendously in programming.

[[Cl...]]

This post has a rating, while others don't. what's up with that?

[[Me...]]

I believe it's based on how many views and responses you have.

[[Me...]]

In case anybody is curious.

[[Da...]]

I usually do it the same way you show. The best part is if for some reason you re-locate the part to a different area , the clearance plane moves with with program.

[[Cl...]]

I do this a lot for horizontal cylinders that are measuring 200° circle segments 180° apart with X+/X- star probes.