Alignment Loop

[[Ja...]]

I've heard that if I use a loop for base alignment and give it a condition, the measurement accuracy will be enhanced.
I was trying to make a loop but I only can make it in characteristics menu. (Base alignment features only appear in features menu.)
Can anyone help me apply a loop?

Thanks

[[SH...]]

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Loop will increase the reptetablity of your program, accuracy depends upon on lot of other factors such as temperature, strategy, evaluation etc.

I think you are talking about base alignment loop, you can create it inside the base alignment definition template.

[[Ja...]]

So, the looping for the base alignment is not related to the accuracy at all?
I have seen a post that said like a stylus checks around the base alignment until it satisfies the condition you give.

[[Cl...]]

It absolutely affects accuracy. Someone might correct me on this, but in layman's terms, each time a loop is initiated, the feature points are probed closer and closer to their actual nominal coordinates & vectors. It keeps doing this for as many times as you've set it to, until the alignments squareness falls at or below the sigma value you assigned to it. Garbage in, garbage out.

[[SH...]]

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Accuracy of your measurement depends upon accuracy of the machine if your working in prismo machine you will get one accuracy ,work in micura machineis you will get another accuracy

It depends upon the your probe qualification perfection.

It depends upon the temperature inside your room,

It depends upon either you scan or touch trigger.

It depends upon your filters and outliers.

So lot of things..

Definitely loop will increase your accuracy , but accuracy is not just a loop.

Iterative Alignment.pdf

[[Ke...]]

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Agreed. There are many things that can affect accuracy, and a stable & repeatable base alignment is one of them.

[[Ma...]]

Loops in base alignments are needed for RPS alignment. If you have just simple features like plain, circle on cylinder and lot of free space around ( aka you are not measuring circle on narrow place ) then you will don't have any bonus from loops.

If you are measuring only machined parts, then it's easier compared to my job - measuring forged parts which are often deformed ( aka plain is not straight - it's bended in many angles ... ).

[[Da...]]

To answer how to do it...
Open your base alignment, click on the loop button, in the text box type in baseSystem().valueA<0.001 or whatever limit you want. You will set the number of times at the top of that window, I usually use 1/5/1.

[[Am...]]

Just want to point out that to put a formula into the base alignment loop break condition it requires PCM. If you don't have PCM you are going to have to live with just putting in the amount of times you want it to loop the base alignment and deal with the program taking longer than it needs to.

[[Th...]]

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The break condition David posted works without a PCM license.

[[Am...]]

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For me it does not.

[[Cl...]]

That's odd?

[[Th...]]

What's your condition look like? It absolutely should not be demanding a PCM license to use.

[[An...]]

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Totally agreed!

[[SH...]]

I have observed a good improvement while I use threaed holes features in alignment.

[[Ma...]]

Of course you can have better results - imagine you are measuring small bolt ( ie 6mm ) but your initial center for that bolt is for ex. 1,5mm offset. Then how precise can be inital touches? Or if you are measuring threaded hole with line scans upwards and filtering - it will also affect results. But if you are measuring clean big cylinder idealy with start align, then loop don't give you more than take your time 😕

[[De...]]

Looping the base alignment is good to use if you fixturing is not the best. It is also good for special base alignments like when your part is all non-standard geometries. Can't remember the name but it is something like 3d freeform or 3d geometry.

[[Sc...]]

I totally forgot how to remove the loop alignment in feature. See screen shot.

Screenshot 2020-10-22.png

[[Ma...]]

Right click on feature and select loops.

[[Sc...]]

Martin, I clicked on feature tab and nothing shows up on right click. Can you give me a screen shot where exactly it is? Please.

[[Sc...]]

I understand that right click on each feature has loop in the menu. The question is the whole measure plan is looped as you can see highlighted on my screen shot on previous post. (1,30,1) is going to run the program 30 times....I created this program about 2 years ago and now I don't remember how got the whole program looped. I want to remove it so I can run program once.

[[Ma...]]

Sorry for misreading. I am not at machine now - perhaps someone knows - never did this for whole plan.

[[Sc...]]

I know right click on each feature has "loop" in the menu. As you see on screen shot the loop is for a whole measure program. (1,30,1) meaning it run program 30 times. That is the issue I am trying to remove the loop.

[[Ch...]]

[[Sc...]]

Chad...you hit right on the nail. WHEW.....running Subsequent Evaluation was a pain...it ran 30 times!! My goodness....what a day I had. Again thanks Chad