Colision with rack when program starts in CNC mode

[[Pa...]]

Hello,

We use a loading system from Zeiss with our measuring machines. After completing the measurement, the machine moves to the safety position behind the rack.

Unfortunately, when we have a loaded tip that starts the measurement (usually in the safety position it is different one, so an automatic change is required) the tip goes the shortest way to the object and collide with the rack.

Is there an option, a method that would prevent it?

At the moment, we use CMM position in the path to the first feature. However, this causes unnecessary routes and a waste of time.

[[Ja...]]

Why do you have safety position behind the rack? Cant you use a safety position that is in front of the rack?

Alternative might be this, if your first feature's clearance plane is +Z then you can just increase your safety clearance cube's +Z value. You might want to use a sub clearance plane Z at the same level as your current clearance plane +Z for the rest of the features to avoid unnecessarily large retractions at end of each feature.

[[Ow...]]

I haven't used a rack positioned like that but , maybe this will help.

Select the automatic stylus changer icon and when it opens, select the probe system you want to modify how it moves between probe changes. After selecting it, select the changer drop down menu and select the Approach Parameters. Here you can change where the probe goes to before and after. I always have mine move up 600mm that way before and after the probe goes to change, it will move the head to the top to clear everything, you can also adjust the distance it stays away/approaches from. In this example , because the probe I'm using has a 125MM probe in the Y+ axis, I pull it back 150mm in the Y-axis.
The size of the CMM may make a difference in how far to move up but, I believe even if the amount is too high the CMM will just come to the Z axis end position (up) but, won't error out and it will continue to make the probe change with no problems.

[[Pa...]]

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Because there is a loading system. Position behaind rack is the only option when I can use system correctyly (the anchor mark appears on the control panel).

Owen, thank you for the instruction. But when probe have to change, everything is ok. The problem statrs when I run program in CNC mode and arleady have a probe that measures the first element.

For even greater clarity, in this program, machine normally had to replace the system before starting the measurement of the next item. There was no problem then. However, once I had to measure one characteristic once again with the system that is normally used in the beginning. That's when the collision happened.

[[Da...]]

Try putting a CMM position at the beginning of the strategy in the first feature to be checked so that the head will clear the rack or go around it.

[[Ma...]]

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Never succeeded with this. CMM always went CP first, then move to position defined before strategy.
Or i was looking on bad place.

[[Ja...]]

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Did you try with increasing Z+ value of clearance cube so that its higher than your current probe rack height? That way it will always stay above the rack

[[No...]]

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...and all CP +Z moves become longer as well....

I think the problem with a CMM position in the strategy is that you can't put anything before the first clearance entry. So it will move to the CP first and only afterwards to the position.

Difficult....
Do you have PCM?

[[Cl...]]

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We have a fixed pneumatic chuck at the center of the machine. The chuck accepts removable pallets that hold dedicated fixturing. After each program has finished we place a CNC end park position in Z+ / Y+ of the base alignment (which is close to the same spot every time no matter which program is run, (due to the centrally located chuck/pallet system) This end park position is far enough above and away from the part so as to avoid probe damage when removing parts and fixtures, as well as it being above and usually just -Y of the rear probe rack. Is this something you could use instead of your current strategy?

[[Ja...]]

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Yes, it will happen but then you can use subclerance planes for rest of the features.

[[La...]]

Do you have PCM? I'm assuming if you're using AAI or FACS you will have PCM. Maybe you can add a code after the home position where if facsIsActive() then getPositionCMM and change the Y value to -100 from it's current position.

You could add this to the inspection_start_pcm.txt so that it pulls forward from the home position before moving towards the workpiece...

[[Pa...]]

Thank you all for yours answers.

The programming opotion look the easist way to deal with it but unfortunately we don't have PCM.

I schould start with this, that I had CP +Y for first strategy... Propably that was main problem, and when I run program in CNC, machine goes with the shortest path to first element/clearance plane +Y.

I changed CP to +Z, and now, when I run program (probes are behaind rack), the machine stays at the same height in the Z axis, goes over the Z clerance plane and starts going directly down to start probing the first element. This heppens even the CP +Z is well below the height of the rack.