Tolerance and Fits

[Thegreatrandino]

I have a design with a 1 in hole. The specification calls for a Basic Hole System RC5. Several tables (e.g. https://www.engineersedge.com/calculators/mechanical-tolerances/ansi-fit-tolerances.htm)

show the hole as H8 and the standard limits as +.0012 - 0 

In the drawing, in the Edit Dimension box, in the Tolerance Method list, if I select Limits/Fits Show Size Limits and choose H8 for the Hole and N/A for shaft, Inventor shows the upper as 1.0030.

My .5 hole, RC2 is correct. I select H6 and it shows  0.5004 as the upper.

What am I missing? Shouldn't it show the upper as 1.0012?

[DavidTunnard]

Can you make sure the model dimension is not set to the upper tolerance limit?

Does the dimension display the correct upper and lower limit within the model space?

I'm working in metric, but I applied an H8 tol. to a 25.4mm hole and it gave me 25.433 - 25.400.  Working this back to imperial, 25.433/25.4 = 1.0012". Not very helpful for you, I know. But makes me think that Inventor will be displaying the correct tolerance.

[Thegreatrandino]

In model space I use the Hole command to create the hole at the nominal, 1 in., dimension.

[rogmitch]

For your information on opening your idw in IV 2021.2.2. the 1" hole displays a tolerance of +0.0013,-0

Roger Mitchell

[Thegreatrandino]

But the tolerances for an H8 1" nominal hole should be +.0012 to  -0 and not the +.0013 that Inventor is assigning.

Draw a 1" hole

Create a drawing

dimension the hole, 

choose Limits/Fits show tolerances Hole H8 shaft n/a

what should the tolerances be for a 1" hole, RC5 fit?

[DavidTunnard]

I think what is happening is Inventor is rounding the tolerance up.

The actual tolerance is something like 1.001299... (so close to 1.0013 that I don't know how you'd measure the difference) If you allow Inventor to show this many decimal places it will display it like that. Any less and it will just round it to 1.0013.

[Thegreatrandino · Accepted solution]

Thanks.  That's only explanation. It's just odd that classes of fits for that hole matches the charts and tables.

Thanks again..............