Dimensions are not correct

[hwu]

The holes' location dimensions should exactly be 0.6875 as shown in the front view. But on the top view, the dimensions on the curve is not exactly correct. What causes this and how to fix it? I am sure the model is right.

My Inventor is 2023

Best regards,

HWU

[CCarreiras]

HI!

Try to create a center mark for each arc. Check if both have the same center.

can you share the file?

[hwu]

Thank you. when I add center marks, the whole circles are chosen. The dimensions are still not perfect.

Please have a look at the attached files.

Best regards,

[ReinierP5648]

The Center mark of the big hole in topview is not correct placed. that is your issue

[CCarreiras]

HI!

What do you mean by "dimensions not perfect"

Seams right to me:

[LT.Rusty]

(edited- I missed something.)

[Ivan_Sinicyn]

This is more likely due to the geometry of the part. The top view projects a curve, not a circle. If you turn the part upside down, the dimensions are correct.

[hwu]

Thank you. How did you make the dimensions perfect? Can you make the red-marked dimensions perfect as well? Can you please send me the drawing that you corrected?

Best regards,

HWU

[hwu]

Thank you. You are right, but I like to show the dimensions in top view.

Best regards,

HWU

[hwu]

Thank you.

How did you find it was wrong? I cannot figure out what was wrong with the big hole center mark. 

Best regards,

HWU

[Ivan_Sinicyn]

I flipped the view. Clicked to set the centerlines automatically and flipped the view back.

[Anonymous · Accepted solution]

Have you considered using Model Dimensions in your drawing view?

You've already got the parameters in the model, use model dims on the drawing and you're all set.

Plus, you can edit these dims in the drawing, no need to open the model and the drawing to refresh it.

[hwu · Accepted solution]

Thank you. Actually, I would like to know why there is the issue.

I also use "Include" the point feature to created center marked, then dimension them. This works as well.

Thanks,

HWU

[JDMather]

---

@hwu wrote:

 Actually, I would like to know why there is the issue.

---

These three curves are NOT circles in the 3D model.

They may show as circles projected into 2D, but actually splines with some behind the scenes conversion prone to rounding error.  Normally we do not show dimensions out to 6 decimal places as that cannot be measured or manufactured.  

[hwu]

Thank you. I was wondering why the dimensions were not perfect?

Best regards.

HWU

[JDMather]

@hwu 

But of course, on the other side of the part where the cylinders cut though perpendicular planar face, they are true circles.  That is why the bottom view worked.

[hwu]

Thank you,

I cannot get what you show here.

After flipped back, there is not center marks, but the blue points.

Best regards,

HWU

[LT.Rusty]

Another way you can get it to work right (without flipping the part) is to use the centerline tool, rather than the center mark.

Using the centerline tool, draw a CL from the left side to the first hole, then the second, the third, and finally stop at the right edge of the part. For me, this put everything in the correct location.

[Anonymous]

@JDMather beat me to it, he's exactly correct in his explanation.

[hwu]

Thank you,

I cannot make it by following your way. The dimensions are still not perfect in the top view.

Best regards,

HWU