Measuring suggestions for this radius

[Underspec]

Imagine a flat surface with a round indention in it. The feature looks like a sphere could sit in it. Anyway, the print calls out a radius on it. How would you measure this with a CMM? Can't use sphere? Circle?

[Paul Sarrach]

No pic? Why do you have to check with a CMM. Could you just use a radius gage, or is there a true pos call out.

[Underspec]

My max radius gage is .5" this is .760". I don't have a way really to cut the thing dead center to get an accurate measurement. So CMM is my best bet.

[BSchwark]

If you have and XYZ location you could translate there and measure radial points and dimension. If you do not have a 1/3 or more of your radius or a wide open tolerance you will have nothing but problems.


BS

[Aguayo]

What about an optical comparator,If you do not have one try a pin.

[Underspec]

Won't be able to cut the part dead center. I would not feel good about that kind of measurement.

[BSchwark]

What is the size? tolerance? how much of radius segment is there to measure?


Bs

[CGoode]

Why can't you use a sphere?

[Underspec]

.761 +/-.005. Sorry too lazy to hook up the digital cam or scanner. The part is a can. On the print it's a cross-section side view and calls out this dimension. The feature is located at the top of the part.

[Paul Sarrach]

Too lazy to scan a pic , and just want us to best quess .

Then check it as a circle , with a start ang stop ang.

Or better yet, if your to lazy to do it, get Minnie Me to do it

[Underspec]

Lol it's Friday. That can be next week's project.

[BSchwark]

Use some modeling clay get an impression and check in on a comparator. Just a thought.


BS

[cmmguy]

What BSchwark said, use an optical comparator. The clay might deform too easily for the tolerance. What we use to do is to make a mold with RTV11 and the cut it with a rasor blade and check it on the comparator. It holds the size very good and does not shrink(we made a mold of a ring gage and checked it with a mike every day for a week and it changed only .0001"). THe other quick method and not as accurate is to use a stick of sealing wax - hold a lighter to it for a couple seconds and then when it is "wet" push it into the radius. Again, check it optically.

[c_bearden]

Turn on Polar Vector Compensation / Offset Alignment to the center of the sphere.......Check individual Radius points.......
Or pour a mold like everyone has recommended.........DENTAL mold Works GREAT!!!!!!!...

Doberman

[Paul Sarrach]

Dental Glue, great suggestion. I forgot about that, have not used it in over 10 years, since I left the aerospace field. There you go underspec. Problem solved.