Profile of a Surface Tolerance - Part with a 195 mm radius on it

[Kamranabbasian]

I have a part with a 195 mm radius on it. the general dimensinal tolorance is +/-0.5mm. There is also a surface profile toltrance for 0.05mm. It is confusing for us to check this part on the CMM. what would be the radius tolorance considering 0.05mm profile limit 194.5 to 195.5 or 194.975 to 195.025?

 

[Stijloor]

Re: Profile tolorance

I have a part with a 195 mm radius on it. the general dimensinal tolorance is +/-0.5mm. There is also a surface profile toltrance for 0.05mm. It is confusing for us to check this part on the CMM. what would be the radius tolorance considering 0.05mm profile limit 194.5 to 195.5 or 194.975 to 195.025?

The profile tolerance takes precedence over the general tolerance.
(Assuming that this general tolerance is stated in the title block).

Is there a basic radius of 195 mm specified? (the 195 in a box?)

The default for profile of a surface is that the 0.05 total profile tolerance zone is equally disposed about the true profile. This means 0.025 above and 0.025 below true profile.

Now, this clarification is provided to you without seeing the actual call-out on the drawing. It is always helpful to attach a sketch.

Hope this helps.

Stijloor.

 

[Kamranabbasian]

Re: Profile tolorance

Thanks for your information. I have attached the sketch al

 

[Jim Wynne]

Re: Profile tolorance

I have a part with a 195 mm radius on it. the general dimensinal tolorance is +/-0.5mm. There is also a surface profile toltrance for 0.05mm. It is confusing for us to check this part on the CMM. what would be the radius tolorance considering 0.05mm profile limit 194.5 to 195.5 or 194.975 to 195.025?

Thanks for your information. I have attached the sketch also,

I don't see a profile callout on your sketch, or a 195mm radius.

 

[Paul F. Jackson]

Re: Profile tolorance

The radius 195 is basic so it does not have general tolerance.
The profile callout has no datum reference associated to it so it can only constrain the form of the semi-cylinder... not its orientation or location.

It is difficult to orient and fit an axis to a small portion of a cylinder but that is what must be done to examine its form relative to a perfect cylinder of 390 diameter.

A number of ideas pop into my mind of artifacts that I would look around for to lay in the semi-cylinder and probe its perpendicular surfaces to approximate the orientation of the cylinder's axis... like the sides of a precision block with precise corner or a Vee block with sharp corners or a couple of large precision roll pins. I hope you see what I mean.

Remember your job is not to discover the size and center of a "best-fit" cylinder but rather compare the minimum possible error/displacement from a best fitted perfect cylinder of 390 diameter.

Paul

 

[Stijloor]

Re: Profile tolorance

I don't see a profile callout on your sketch, or a 195mm radius.

Initially, I could not see the whole drawing, but by using the "outlining" function in "Word", all views became visible.
It takes some "playing" with it...

Stijloor.

 

[Jim Wynne]

Re: Profile tolorance

Initially, I could not see the whole drawing, but by using the "outlining" function in "Word", all views became visible.
It takes some "playing" with it...

Stijloor.

Thanks. I converted it to PDF and added it to the OP's post.

 

[CycleMike]

What kind of CMM software are you using?

 

[Kamranabbasian]

mitutoyo; Part Manager V3.0.R6 Edition 17 in Mcosmos-2

 

[CycleMike]

I'm unfamiliar with that software, so I don't think I can help..........sorry.