Question about calibrating the tool probe. I haven't used it yet, but I was planning on calibrating it after I recieve my ring gage. I not exactly sure what to use a a calibration bar. Can I just use a dowel pin and set it with that? Also how should I calculate the actual length of the calibration bar? Do I come from tip of the pin to the flat just below the taper of the holder? Does it have to be the same length as the probe itself?
Renishaw seems to set all it's tool length measurements from the gage line to the bottom of the tool. The gage line starts at the top edge of your tool holder. looking down on the holder from the pull stud right below the end of the taper the tool holder will expand perpendicular to the spindle axis to a diameter that engages the drive dogs on the spindle. This is the top gage line surface ( as explained to me by the Haas Tech.). The bottom measurement is the bottom of the dowel or whatever you use to calibrate the tool setter. Diameter of the dowel is not a factor.
The Master Tool diameter: This is established by the first VQC template that is used to calibrate the TS27 presetter. You put a known drill rod, shank of an endmill or other precise, round piece of metal. Measure it with your best, trusted micrometer. Whatever that number is, will establish all future tool diameters. It doesn't have to be exactly 0.250 but if you measure 0.2474, tell it so.
You now go to touch that off of the TS27. It trips the switches from three directions. It knows what the diameter is because you typed it in. It knows how far the table moved in each direction. It does some simple math and figures out where the trip points are. It's done.
The Master Tool Length: This is established by the second VQC template for the TS27 presetter. Again: you measure the tool and tool holder (in this case: your drill rod from the first step above). Measure from wherever you want. I measured from the spindle face. Others measure from the gauge line. Measure that distance.
Whatever distance you type into the control is what teaches it the length from the spindle to the presetter. The actual length is unimportant but if you're like me, you'll want to get it as close as possible.
After you touch that to the presetter, you can go into offsets and look at the tool length. It will be exactly what you typed in. All future tool lengths are relative to this number. The system doesn't need ultra precision because it's later going to learn how long the probe is. It's going to use that number for all future work offsets.
The Master Probe Length: The third VQC template is used to measure and store the probe length. I prefer to keep the probe in the last pocket (T20 in my case). Once it knows how long all of the tools are and how long the probe is, it can establish a Z plane anywhere the probe can reach.
The Master Probe Distance: The last VQC template is used with the ring gauge. The only reason for the ring gauge is that it's difficult to get an inside dimension that is truly accurate. A ring gauge is easiest and most precise but any bore would work if you could measure it to your satisfaction. Again, you will tell the control what the diameter is (on the ring gauge).
The table moves the ring gauge around and learns how far it has to move the probe to trip its switches. It takes your entered value, does more simple math and learns how much probe movement to subtract for switch variances and other mechanical differences.
If you set all of the four above items, everything is calibrated. Each step only accomplishes one task, based on an outside measurement you gave it. The red highlighted dimensions are supplied by you and are critical for accurate calibration. That's why you need them to be a known diameter. It figures out the probe length on its own.
The master tool length is for your own reference only. In the end, they're all relative to the probe length. The tool lengths in the offsets table will make more sense to you if you measure it the way that makes sense to you.
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