Manufacturing Information Solutions

[franke]

I got this info from a friend.

A spindle mounted probe can be one of the best tools you'll ever buy for increasing productivity but keeping it calibrated or calibrating after breaking a stylus (a rare event of course) can be a pain. Using the program and fixture in this tip makes calibrating a simple task that can be done in a few minutes. This example calibrates the probe's stylus offset and diameter. The probe's tool length offset must be calibrated before using this example.

The first step is to purchase a 1.000 ring gage that can be dedicated to the fixture. Next, decide how the fixture can be mounted to the machine quickly and easily. The fixture in the figure is held in a three jaw chuck on one mill, bolts to a sub-plate on another mill and bolts to a two axis tilting table on another. The key feature is that it can be mounted quickly and without major problems.


In the figure, the ring gage is held down on the left side of the fixture and a replaceable aluminum plate is held on by two cap screws in the center. To calibrate the probe a boring bar is used to bore a hole in the plate at X0Y0. This establishes an exact center to set the stylus's X, Y offset. When the bore gets too large simply throw the plate away and make another one.

To calibrate the probe, a G54 coordinate system is established and then the top of the plate is probed to set an exact Z0, and the bore is probed to set an approximate X0, Y0. Next, the boring bar opens the bore up to establish the exact X0, Y0 of the plate. Make sure that the bore was completely cleaned up by the boring bar.

The probe is then positioned over the plate and the bore is probed using the standard Renishaw 9802 cycle. Next the ring gage is probed using 9804 Vector calibration. The whole cycle should only take a few minutes and when finished the probe is calibrated for stylus offset and stylus diameter.

In this example, G54 X, Y, Z are preset in the program using the code

#5221=-9.1607
#5222=-6.8235
#5223=-21.7230


The code #5203=0(CLEAR COMMON Z) is an important safety feature that you should include in all probe programs. If the operator had put an offset in the Z axis common work shift and then runs the probe, the offset is added to the coordinate system and the probe will error. However, if the operator notices the offset, presses Slide Hold, clears the offset and then presses Cycle Start the machine will rapid the amount of the offset and wont be in protect position mode. In any event, this one line of code will prevent wasted time.

You will have to use values that fit the location of your fixture. Presetting the coordinate system like this removes the operator from the setup and eliminates the risk of a crash and the lost time indicating the fixture. The probe is tool 19 in this machine. You'll have to edit the tool change to fit your particular machine.

Here's the program: