Measurement of a Radius on Drawing

[Alpine]

Hi I've long lurked here and appreciated the mountain of information on this forum. It is easy to feel isolated in a quality role, and having this forum as a back up has made my role that little bit easier. Today we found a problem with a part manufactured for us. It is pipe that has two 18 radius bends that we fit other parts onto. It appears that the radius is out causing assembly issues. Is anyone able to tell me how to check this accurately? I've thought about a radius gage but can only locate to 15. I've carried out a search here and couldn't locate anything. Many thanks

 

[J0anne]

Hello Alpine. I would check it on a CMM.

 

[Michael_M]

Another way is to turn a diameter (2x radius). Turn 2x diameters, one at the smallest allowed, the other at the highest.

For example, the radius is 18 +/-1, turn one diameter at 34 and another at 38. The part should 'fit' within the smaller and not fit within the larger.

This is a quick and dirty method and remember to verify the diameters with a calibrated instrument.

 

[Golfman25]

Depending on the size of your part some type of comparator would work.

However, if you are talking about a formed outside radius, be aware that it will not be a true radius. Stretching of the material will be involved. If that is the case a go/no-go functional fit is probably the best. Good luck.

 

[Alpine]

Another way is to turn a diameter (2x radius). Turn 2x diameters, one at the smallest allowed, the other at the highest.

For example, the radius is 18 +/-1, turn one diameter at 34 and another at 38. The part should 'fit' within the smaller and not fit within the larger.

This is a quick and dirty method and remember to verify the diameters with a calibrated instrument.

Thanks, I will give this a go today. Quick and dirty is good, as I want to reject these parts but have to quantitatively prove they are not to specification.