[How do I?] Radius gauge for 'large' values of radius

[AGCB97]

No numbers on it?

 

[AGCB97]

The spherical diameter should be the same as the maximum diameter of the race

 

[Alcap]

Do you have an outside mic that you could measure it ? It should measure the same at different spots if a sphere

 

[THX-1138]

No numbers on it?

Nope, pre-stamp. The finish appears complete and polished, but I haven't tested it for being heat-treated yet. It's either pre-hardening and not yet stamped, or the info would be stamped on the rim of the inner race. At a guess.

 

[THX-1138]

Do you have an outside mic that you could measure it ? It should measure the same at different spots if a sphere

Unfortunately, the subtended arc is so small that I would suspect the precision of the results would be close to the noise.

Right now I'm thinking of cutting a hole in some sheet metal that exactly matches the maximum diameter in the XY plane, and then rotating the race 90° about the X axis and passing it through the hole to see if the outer curvature exactly matches the diameter. (For best available values of "exact." ) If it does, it's spherical-ish.

Meh. The main reason I want this information is so I can model it exactly in SolidEdge for subsequent diagrams of the gyroscope project. So, as usual, I'm ratholing myself.

But I've learned a lot in this thread, so it's not a loss. Thanks, everyone, for your help with this! The sheet metal radius gauge sounds like a useful acquisition, too.

 

[extropic]

@THX-1138

I'll bet a weeks pay the exterior is a SPHERICAL form. If not, there is no solid housing design that would allow the race to pitch and/or yaw to achieve the alignment typical of such bearings.

It was already suggested to measure the diameter at multiple points (front to back, center to center, back to front) across the face of the arc.
This is a simple and precise way to verify whether or not it's a spherical form. It does require tools and personnel capable of measuring with the desired precision.

Using a radius gauge is a rough approximation compared to using a micrometer.

On the other hand, it's a hobby. Make it as challenging as you like.

 

[Alcap]

In the late seventies i worked for Ingersoll Rand Turbo Product Div. , they made gas compressors for oil and gas industry. I ran vertical boring mills and one of the jobs we did was both inside and outside of the spherical bearing ends simlar to this picture , when we knew the part was correct it would measure the same in all directions like extropic mentioned above .

 

[pontiac428]

Spherical bearings must be spherical, or else they'd call them eastern import bearings, square bearings, egg bearings, or something equally descriptive.

 

[THX-1138]

Point well taken. I don't know if I have a micrometer that big or not. And I'll have to clean the protective coating off. I'll be checking.

 

[Deleted member 69715]

You can machine a disc with a 4 3/4" hole in it, then split the disc. To save you time just assume the contour on the OD is spherical. That type of bearing is used in pillow blocks in a spherical cavity. The shape needs to be spherical in order for pillow blocks to self align.

This. Former employment we had to make such to gauge radii outside the range of available gauges for shop personnel to use. As to the effectiveness the customer found product to be in tolerance and accepted it.