Probe Tip > CREATING > Probe.dat

[Gary Fitzgerald]

I need to create and use a cylinder tip with a flat bottom. I need to be able to touch on flat bottom and on diameter side. I added this tip to probe.dat file for a 3mm diameter x 40mm total length:

ITEM:TIP3BY40MMSHNK M2
begintip
ribcount 10
color 142 142 142
cylinder 0 0 0 0 0 -3 3
cone 0 0 -3 3 0 0 -10 2
color 255 0 0
cylinder 0 0 -10 0 0 -40 3
hotspot 0 0 -40 0 0 1 3 30 shank
endtip

Problem is I cannout get tip to work on flat bottom and on diameter side with one entry. When I change the hotspot 3 to 0 it works on the flat bottom but goes to center of diameter not side and when I have it as entered it touchs on diameter side but it is 3mm above the hit in Z.

Any help is greatly appreciated.

Gary Fitzgerald > Big Red

[Wes Cisco]

I am generally against cylinder probes because they must be absolutely perpendicular to the feature or they give bad data. I have never heard of a flat bottom cylinder probe before and I would not trust it. If you must use a cylinder and take hits with the bottom why wouldn't you want a radius? Seems you are just inviting Mr. Murphy to have a big party on your CMM table. Most probes are spheres because that ensures a single point of contact and helps to isolate the vector of the hit. With a flat bottom tip you could easily be taking a hit with one edge of that bottom diameter but the software/CMM would be recording it as if it were a hit at the center of the diameter. I do not even want to think about what it could do to your vectors. I do hope this helps.

[Matthew D. Hoedeman]

You can do this, and if you CAN do this will depend on WHAT you are doing. Basically, you can NOT use this for TIGHT tolerance, but this is what I do:

1) Use just plain old extensions
2) Use your mic's and get a good diameter reading, and check it a lot to see roundness
3) Create the tip in the probe.dat file like you did
4) DO NOT CALIBRATE THE TIP

You will only be able to use it a 0-0, but your Z to Z values from touch-off to reading will be right and your XY to XY will also be right. There error creeps in for the probe comp in the XY directions since rarely will a probe actually calibrate at the size it mic's at, simply because of the ahrdware in the CMM. I have done this when I had to digitize flat blank, it is MUCH cheaper than a ceramic probe, will not shatter like one, and for my application (flat blanks) if I am within 0.010" it is good enough since the data then will need to be manipulated to make a smooth, easy to produce blank for a die.