Stylus Standard Deviation

[[Jo...]]

I wanted to get some thoughts on this stylus system. I was informed that it has always qualified at .010mm or higher. It has recently been providing inaccurate results. The horizontal shaft is ~8 inches long.

Today, we inspected the tips, and they appear to be in good condition (no visible flat spots or aluminum buildup under microscope). We verified all connections are tight. Both tips qualify at the same sigma value and radius (.005 mm oversized). We then tested qualifying each of the tips at a 20-30% probing dynamic, and that yielded .001mm. We also tested adding a counterbalance to the system, and that made no difference at the 100% probing dynamic.

Does this seem right to you guys? Could there be something else causing issues? I have limited experience with stylus systems like this. We also have a couple other setups like this, and they qualify around the same sigma value. My leading theory is simply that the shaft length causes it to “shake” during probing, so the lower dynamic slows this movement down, allowing for more stability.

[[Ma...]]

I would suggest a counterweight.

[[Jo...]]

what happens when you build maximum compact with just the two styli and test them seperatly?

Would be a good starting point knowing that this gives the expected results before looking further.

You could then start rebuilding link for link, maybe that shows a weak link (a link with more flex than expected).

 

I dont know the system so just speculating here, but it could also be wear of the modul itself. Meaning it was once "strong" enough to support the weight but isnt anymore.

Edited 5 hours ago

[[Ri...]]

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Yep, for that length and probable weight, I would say a 40mm extension and about 50g of weight will work.

I have a similar probe with this configuration.

[[A...]]

I recommend a counter weight as well along with taking it apart and cleaning the threads of all connections. The threads usually get me. I also find it ok to probe at 1% dynamics if needed.

[[Ch...]]

We have a stylus system that is very close to that one.  It often qualifies between .0005 and .0010.  We do use a counter weight, but it still doesn't qualify that well.  We only use it for stuff with loose tolerance since I know its not that accurate.  

 

HOWEVER, I would suggest trying a different adaptor plate as well.  The XTR adaptor plates are more complicated which just means that there is more that can go wrong.  Which sucks, cause those things are $$$.