The ring gage is brand new. I bought it for this purpose. It also checks pretty much right on with my calipers to the thousanth and it measures within +/- .00005 with my Mitutoyo inside mic., however I calibrated the mic with the ring also, but double checked it to my my outside mic and my calipers referencing a brand new gage block set.
So, I kinda have to trust the ring gage is okay. It is certainly more precision than the probe or even my machine I would say.
The error did not change when I rotate the probe 90 degrees and check (without doing a new calibration).
However, I also rotated it 90 and did do the calibration all over. It still had too much error.
I tried changing the Y offset manually in the machine.ini just to see how it reacts. I can dial it in to get the Y- correct, but then I did not check the others (Y+,X+,X-). I just wanted to verify it was working and kinda how it works.
After that, I set things all back up again and rotate the probe to a new position where the LED is facing the operator. This kinda falls where none of the 3 internal pins are in line with an axis. I wanted to see what it does. I centered up the X and Y to the ring gage with an indicator again and recalibrated the probe.
This is what I got this time:
XOffset=-0.001253
YOffset=0.002593
Radius=0.056330
I then did more measurements than other tests to have better data. I probed Y-,Y+,X-,X+ to get zero with the probe at each location followed with a check at each location with the edge finder.
This is what I got with that check.
.200 Dia Edge finder measurements:
Y- -.1014 (Target -.1000)
Y+ .0958 (Target .1000)
X- -.0979 (Target -.1000)
X+ .0996 (Target .1000)
So, I consider this still crappy.....
After every calibration I always measured the ring gage with the probe and it was almost always within +/- .0001. It did go out +/-.0002 a couple times. So I seem to be able to measure the bore of the calibration device very accurate, but edge finding sucks for some reason.
The backlash on my machine is a little worse than I would like at .0014 in Y and .0030 in X. I have backlash compensation on and if I go back and forth .015 it will usually land less than +/- .0005 from target or better (my dial indication is .0005 resolution and it usually lands on or within half way of that first mark off zero (so likely +/-.0003 at worst).
Open to ideas? This should at least be better data than I had before to work from.
When I first got this probe up and running, I did have to disassemble and clean all the contacts. The LED was kinda sensitive and flickery (indicating some resistance in the contacts). After I did this, the LED and signal seem fine.
Another thing of note is that if I probe the same thing over and over, the repeatability is always on or within +/-.0001.
I am wondering if I could just manually adjust the radius and XY offsets to dial this in? Is it possible the auto calibration is just not great, or do I have a probe or machine issue?