There seems to be a conflict between the General unit length selection, versus the setting in the Dimension setting of Decimal versus ft & inches.

If General is set to centimeters, the General setting of ft & inches shows inch measurements. So does one setting override the other?

A 3 inch dimension will show up as 7.997369 cm, which equals 3.14857 inches, not 3 inches.

(I see that dimension values placed on a drawing DO dynamically change, with scaling. (?) )

I managed to get a 2.5 inch, which equals 6.35 cm to show as 6.283185 units.

Anyway, I am very confused :-)

- Brian

Edit: I see that when Dimension is set to ft & inches, the fractional display (e.g.1/2") rounds off (?) or rounds up or down (?), the displayed dimensions, which may explain some of the conflicting lengths(?)

If cutting a board, the desired length may be off a little?
Maybe say 1/2" +/- instead of 1/2"???

Setting fractions to e.g. 1/64 or 1/128 shows a less inaccurate length?

Hi Brian, I'm having some difficulty following this part:

You wrote:
> If General is set to centimeters, the General setting of ft & inches shows inch measurements. So does
> one setting override the other?

If Options > General > Unit system is set to Centimeters, there is no "General setting of ft & inches" displayed ... ?

- Michael

Hi Brian, for this part:

> A 3 inch dimension will show up as 7.997369 cm, which equals 3.14857 inches, not 3 inches.

Are you referring to this one here?



That is displayed as 3" because the fractional precision is set to round to the nearest half inch, here (under "Details...") :



You're comparing a high accuracy decimal setting with a low accuracy fractional setting.

With a "Fractional display" of 1/2, the displayed result will be rounded to the nearest 1/2 inch.

The distance is 7.997369 centimeters which equals 3.1485704724 inches.

With a fractional precision of 1/2 inch, it will round 3.1485704724 to either 3" or 3 1/2" whichever is closest and 3" is closest.

If you want more accuracy in the feet & inches display you need to adjust the "Fractional display" to be smaller so that it will round to the nearest 1/16 or finer.

Does that help?

- Michael

Hi Michael,
Thankyou for the clarifications. They help a lot!

The second "General" should have been DIMENSION setting...
> If General is set to centimeters, the DIMENSION setting of ft & inches shows inch measurements. So does
> one setting override the other?

When I am doing carpentry, depending upon project, the tolerance is often 1/8 inch, or 1/16 inch.
It can also include an abstract unit of measurement called a "fuzz", which might approximate 1/16, or 1/32.
The tape measure is in feet and inches, and fractional inches.
Metric tape measures are rare, but I did manage to buy a metric one, for CNC projects.
Metric thinking is still difficult.

For the current project, I think that I will stick to Dimension Decimal setting, and avoid fractional inches :-)

I think that in one editing session, before saving, the length numbers are still fluid, between centimeters and inches (?), but after saving the .3dm, the existing dimensions do not respond to a change in general setting between centimeters and inches. (?) The saved and reloaded .3dm's Dimension DO respond to scaling.

- Brian

Hi Brian,

re:
>The second "General" should have been DIMENSION setting...
> > If General is set to centimeters, the DIMENSION setting of ft & inches shows inch measurements. So does
> > one setting override the other?

Yes, dimensions have their own individual formatting properties.

If the dimension has Distance display: "Feet & Inches" set, it will display a feet & inches value regardless of the current model units (except for "No unit system").

Please let me know if you still have a question on this area.

- Michael

Hi Michael,

I believe that I now understand that the Fractional display, (for Feet & Inches), incorporates Rounding.

In the Object properties popup, and the Options > Dimensions box, a suggestion would be to change the label "Fractional display:", by adding the word "rounding", or "rounding precision".
Or the word or words could be added after the fraction selection box. (???)

- Brian