After spending a day measuring, calibrating, adjusting and calculating, I have come to the conclusion. That my probe tip is not spherical. From my calculations the probe to appears to be .0157mm longer than it is wide. Unfortunately I can only measure to .002mm strategy and since the top of the probe tip has a ceramic rod protruding from it and I don’t own or have access to a comm machine I cannot measure the probe tip to be sure.
Here is the problem. After a lot of adjustment I have the measured diameter of a 7.998mm diameter gauge pin being probed on x+ and x- resulting in measured values of 3.994mm and -3.993mm. However every time I probe Z the result is always 4.056 a 4.057. I probed in 10 degree increments. The only logical conclusion is that my probe tips axial diameter is larger than its rotational diameter. Is there any way to adjust this? I have ordered a couple new probe tips from different manufacturers but I have no faith that this will solve the problem. Anyone else have this problem?
How much of a problem is this for you? We all want our machines to be perfect, but you’re chasing the machine’s ballscrew accuracy spec and backlash and temperature and probe repeatability and everything else down that small. A degree C temperature change will resize the machine more than .002mm just from thermal expansion.
You should be able to rotate the probe 90 degrees (or 45 or 30) in the spindle and see if the error follows the probe or spindle.
Harold,
No, there is no way to adjust this, it’s beyond the capabilities of our probing routines and Pathpilot. Some companies like Renishaw solve part of this by orienting the probe for every touch but the way they completely solve the issue is with a calibration routine that probes hundreds of times at various orientations to map the surface of the stylus and apply comp values (“Supatouch” is a term you can search).
I will also agree with Roy, don’t worry about it. Thermal deviation and repeatability of the machine will be far more impactful on measurement results that any deviation of the stylus.
Thank you,
Norman
My question is about understanding the process between the probe and the result because the probe data only makes sense if the probe tip is longer than it is wide which doesn’t make sense and at over $100 per tip it’s a bit expensive to just try another one. I’m making a pinion for a watch where the teeth are .13mm so even .008 off is quite noticeable. Every time I probe for the center on my an axis it’s off so I have to play find the center with a microscope and try again.
Did you try rotating the probe 90 degrees in the spindle and seeing if the error followed the probe?
Why does it matter? As long as you correctly set the probe length in PP, it becomes irrelevant.