Snap to grid is off by 0.0000001192 mm

[info98KUJ]

Hi,

I have an issue with snap to grid

How to replicate

  - Start a new design

  - New sketch

  - 2 point rectangle

  - Move the cursor anywhere, so it snaps to the grid and click to set first point

  - Move mouse anywhere else, so it snaps to the grid and click to set the rectangle

  - Click sketch dimension, click a side of the rectangle then click the origin point

  - Click once more to place the dimension

At this point it shows the dimension "8.0000001192 mm"

This cannot be right, as it is throwing everything off?

have I change a setting somewhere?

Many Thanks

[bentwookie]

What you're observing is Fusion bumping up against the precision available in a 32 bit floating point number. In the range of numbers from zero to one, the best precision you can get is 0.00000011920929. It's actually somewhat of a thorny problem to mitigate.

They could cut over to 64bit floats, but then we'd just be talking about the grid being off by .000000000000000222046. I think AutoCad uses 64bit floats. They could cut over to different ways of representing numbers which don't have this particular problem with precision but they'd most likely be much slower.

If it was me, I'd opt not to display numbers beyond the precision of the system and call it a day. Assuming the errors aren't accumulating, it's off by the width of a hydrogen atom. My CNC doesn't cut that precisely 😉

There's a setting that limits the amount of precision the UI shows. (Preferences : Units And Value Display : General precision) Is yours set to show a ton of precision?

[g-andresen]

Hi,

My recommendation:
I assume that an object is developed whose dimensions are defined by the designer and not as suggested by the grid.
Therefore, deactivate the grid and create the sketches exclusively with self-generated dimensions.

Günther

[info98KUJ]

ok thanks guys, was mainly checking to see if it was a setting/preference that was tweaked or out of wack.

Thanks again

[wmhazzard]

Snapping to the grid does that, if you type in the dimension in the sketch, you will not have the error. It is best practice to not snap to the grid.