Renishaw spindle probe question: Checking concave radii for size

[Matt@RFR]

Check out the attached picture. I need to measure the radius of the blue surfaces. There are two parts, but when mated they have a gap between them, meaning the walls of the parts don't go vertical, so I can't measure with calipers, dial bore gauges, etc..

My original plan was to use gauge pins that measure at the low side and the high side of the tolerance (+/-.002", incidently, on a R.477") and simply lay them in the part and use a loupe to see where they make contact with the part. I think that would've worked fine, but the gauge pins are taking WAY too long to get here and I need to get these parts out soon.

I looked through all the literature I have, but didn't see a suitable probing cycle. Anyone know how I could probe the radius at 3 points and have the probe tell me what size it is? One of the features' axis will be parallel to the Y axis of the mill.

Beyond that, any other ideas how to measure this? When I accepted the job, the tolerance on those radii were +/-.010". And yes, he saw a hefty price increase as punishment.

[Geof]

Originally Posted by Matt@RFR ......My original plan was to use gauge pins that measure at the low side and the high side of the tolerance (+/-.002", incidently, on a R.477") and simply lay them in the part and use a loupe to see where they make contact with the part. I think that would've worked fine, but the gauge pins are taking WAY too long to get here and I need to get these parts out soon.....

Do you need gauge pins made to some specific tolerance? Is it not possible to make your own?

[Matt@RFR]

Z class gauge pins in any size, in .0005" increments are just over $8/ea from McMaster, hardened to 60-62Rc. My time is so tight that I rather buy than make, especially when the price is so low. No big deal to make them, but I wanted to explore different ways of going about this since I need to switch gears anyway.

Either way, it's a good opportunity to learn something.

[renitek]

Do you often use probe to check a 3D part? If you answer "Yes", consider to use OMV software. It designs by Delcam, but can purchase from Renishaw ink. The concept is checking your parts on the machine table after cutting finish.
1. To Load up your original CAD format into OMV. (The software is executed in Windows systems.)
2. To pick you want measuring points.
3. The software will be creating a path of NC measuring program.
4. To load the NC program into your CNC controller and install a probe in the machine spindle.
5. Execute the program that will be measuring parts and sending the point data to PC or save them in PCMCIA ports by DPRNT command.
6. The OMV can verify the tolerances between original figure and measuring data.
7. Print to report.

[guypb]

You could also use Renishaw's Productivity Plus to achieve the same thing from a model, with the added benefit of updating tool and work offsets.

[Matt@RFR]

New software is out of the question. This kind of thing is abnormal for me.

So It seems as though the probing software I have is not capable of what I want to do. Ok, gauge pins it is. Thanks guys.

[guypb]

Can you put it on its side, and use a 3 point bore cycle?

You'll have to use a different calibration routine to the standard Haas VQC calibration cycle as it doesn't map all stylus vectors.

Note that to measure a radius under 180 degrees using discrete points is always flaky.

Otherwise do a Z point, and X & -X cycle - that would give you an indication of metal on condition.