Using styli with long shafts (Flex issues)

[[Ri...]]

I have inherited two probes, both are Ø2mm x 100L and Ø2mm x 120L.
The 120L probe is only in the Z axis, it seems stable when qualifying, holding a sigma of .00009-.00011 (inch).
The other 100L is in the XY axis. This is on an XTR Sensor and has many rotations.
I am finding that qualifications in one axis (X) is better than the other (Y).
Typically, I see sigma's ranging from .00009 to .00019 or higher.
Currently I have tried 200 force (f) and 50% dynamics (d), 100f and 50%d, 100f and 30%d, 50f and 50%d.
None of these produced stable results in multiple qualification runs. All are Carbide shafts.

Any tips on using flexible styli are appreciated (except "Don't" 🤣 ).

[[Cl...]]

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Carbon fiber? For those lengths we use either ceramic or Tungsten
carbide. On a VAST XT Gold.

[[Mi...]]

We use many in the 100mm+ range this is on XT Gold though, I'm not sure what XTR's limits are, it makes sense to me it wouldn't be as capable with long/heavy stylus systems. One of our bread and butter probes is in +X, 80mm extension + 100mm probe.

Quality probes are key, when we've struggled with calibrating the long probes it was due to their age and/or our stores department switching to a cheaper supplier. Zeiss or ITP or nothing...

That said, we have some 8x114mm carbon shaft ones from ITP that won't calibrate well. They are 15+ years old and the other guy said they just never calibrated well.

For any probes within the "normal" range, we calibrate at all default forces.

[[Ri...]]

We are using Zeiss, Q-Mark and ITP.
One particular Stylus is in the Y axis "Ø2 x 100 x 80 Ext". The shaft (Ds) is Ø1.5.
What settings are you using?

[[Mi...]]

Well throw QMark in the garbage first of all, or at least expect S values double what Zeiss or ITP ones will give you, also you can expect them to fall apart after a few months of use.

And we don't use anything with a shaft that small over 50mm. It doesn't work reliably regardless of settings as you're finding, other solutions have to be found. Usually an extension with a shorter shaft, or various funky probes like these. We've started adapting M5 down to M3 or M2 for stuff like this.


Our 100mm probes are all 5mm Rubies with 3.5mm shafts, our 114mm probes are 8mm rubies with 5mm shafts.

This is our closest configuration to your example. 3mm ruby, 60mm long, 60mm extension in both X directions. 2mm Carbide shaft on the probes, standard calibration settings.

Star Port 3.PNG

[[Ri...]]

Q-Mark had issues years ago, I do not see them anymore.
I get the roughly the same Sigma as I do with Zeiss.
Anyhow, this is the problem probe.

Capture.PNG

[[Ke...]]

Does XTR have the same rotation repeatability issues as the XXT?
I would imaging that the overall length of the probe would add to any existing repeatability issues.
I'm presuming that the overall weight of the probe is within recommended guidelines?

[[Ow...]]

I'm with Keith on the rotational repeatability question regarding the XTR.
Other than that and it shouldn't be a problem at that weight but, might try putting a balancing probe or something of equal weight on the other side to see if it gets better. Could also try replacing the extension, especially if it's the old aluminum extensions Zeiss doesn't use anymore. If that much sigma error is a problem regarding the tolerance of the feature('s) being checked, you may have to go to qualifying with points only (no dynamic) and measuring with single points as well.

[[Da...]]

We have one machine with an XTR head. We will construct Tee probes to reduce rotations and keep balance, this does help with repeatability. Can you use a stepped probe instead of that long 2.5mm?

[[Mi...]]

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Have you tried counterbalancing the arm-probe with a another one similar (only to see if the sigma decrease)?

[[Ri...]]

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Unfortunately, I need all the length I have for deep holes.

[[Ri...]]

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There may be rotation issues, I have a post on the forum about measuring a sphere from -Y to +Y using a pattern (3) and the first X location after rotating to +Y is always about .0004 (inch) off, the reaming two of the pattern are about .00006 (inch).
Weight is well within guidelines.
I have a similar Ø3mm stylus that doesn't have an issue qualifying.

[[Ri...]]

I will try counter balancing.
Conversely, this probe build works great as is.

Capture3.PNGCapture2.PNG

[[Da...]]

Just as a test, and only if you have the components, try building a second probe and checking that. If the sigmas are the same for the same rotations, then the head may be the problem? Also, disassemble the probe and look for nicks or dings on the mating surfaces.