We're going to modify a probe ball

[[Da...]]

We have a job that requires a concentricity of a very small ID chamfer at the bottom of a bore. There is a clearance cylinder below the chamfer. The chamfer is so small, and the depth to the adjacent face varies more than the width of the chamfer, that it makes it very challenging to check consistently. So, to alleviate the problem, we are going to use a self-centering point and a 10 mm probe to pick up the location. It will sit at or very near tangent point on the chamfer. The hook is that a 10mm ball will not fit in the ID cylinder above the chamfer. So, we are going to grind the OD of the ball just enough to fit into the bore with some clearance. We can calibrate off the untouched areas of the probe ball.... We are a grinding service, and this is not a stretch for us.

Any foreseeable problems?

[[Je...]]

While I am not "advising" this in anyway, I always encourage everyone to experiment. The 1 caveat with this scenario is, if you are using an XXT, this is off the table. You cannot qualify a stylus without 180° coverage. This is not editable (thought the entry fields gives you the impression it is)

[[Ke...]]

I will throw in that both heat and coolant are not the friends of probes, they will likely break down the adhesive connection between the shaft and sphere

[[Da...]]

We will end up with 150 degrees left over, so it's not a very large modification. Thanks for the heads up on the coolant, we will try an alternative. (possibly straight water)

[[Mi...]]

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Any results on this?

I've seen it done once before actually. I struggle with understanding the need, but I'm probably just not reading properly.

The example I saw was a distance under pins measurement where the pins needed a flat spot to fit.... and the programmer didn't know about the Tangent construction.

[[Da...]]

At this point we have scrapped the project. There is not enough need for the modified ball. Since receiving the prints for the entire family of parts it turns out that standard sizes fit for all but the one part number.

[[Ri...]]

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I can say from experience, that I have done the same thing to an 8mm ruby.
I needed the 8mm "crown" to contact on a cone and it had to pass down a long bore (90mm) that is Ø7.781.
We created a manual tool to check depth vs the stylus, made a few adjustments and it has worked as planned since then.
The stylus is in a production environment on a Prismo Ultra and several other Prismo's in lab conditions, it is used to inspect Glow Plug depths on a Diesel Head.
The company makes 256k+ heads per year.

When I conceived the plan to "grind" the OD I did not have grinding equipment, I lapped the OD to a size with several stones. After determining this is viable, we had tools made by Q-Mark.

[[Da...]]

God to hear Rick, while we aren't going ahead it's good to know the concept works well for you. Its ammo for future solutions !

This one of the great things about the forum. I read solutions to problems that I don't even have, and that knowledge, that there is a solution, is what I get from it. Thank you all !!!