VAST XT: forces in Tensor mode (I am stunned!)

[[No...]]

I use Tensor mode for qualifying my styli. As you probably know: there are 2 parameters you can set: [list=]

Probing force (in mN)

Dynamic probing (in %)

I was stunned to see that the qualification of the probe is NOT performed with force you choose.

If you set dynamic probing at 30% or more: qualification is done at 200 and 800 mN. No matter what force you choose (anything between 50 and 1000).

If you set dynamic probing at 20% or less : qualification is done at 70 and 150 mN. No matter what force you choose (anything between 50 and 1000).

At least that happened on my Contura with XT sensor and C99 controller. I used a 3 mm (0.12") stylus in the #5 position.

This may be the reason why people break small styli. If you select a very low probing force (let's say 50 mN) and you select 30% dynamic probing, qualification will be at 200 and 800 mN! Ouch...

During the sixpoint mode (instead of Tensor) the probing force will the same as you selected. This might me the way to go for styli of 0.5 mm (0.02") and smaller. And use a single point strategy rather than scanning.

Does anyone know why Tensor mode only has 2 options: 200/800 and 70/150 mN ? And why the forces are not equal to the forces that you choose?

[[Da...]]

The tensor mode's scanning part has one main function and that’s to calculate the bending parameters of the stylus. The actual calibration is always done by the touch probes afterwards. For that reason, there will always be a low force and a strong force used.

I have found, that very thin styli should not be calibrated with tensor mode, or if you absolutely insist, recalibrate the stylus an hour later with just trigger points. The tensor of the last tensor mode calibration will not be deleted, so there is still information about the bending parameters of the stylus.

Also, if you have repeatability issues with a stylus that seems stiff enough, try not using the tensor mode. If often resolves otherwise unresolvable problems.