topic Re: Problem with Snap Precision in AutoCAD Forum

Problem with Snap Precision

Anonymous — Mon, 21 Mar 2016 14:14:47 GMT

I'm stuck in a situation that's causing me trouble. This is what's happening:

1. I made a Line and a Circle.

2. Now i need to get a Line from the intersection point betwen my first line and my first circle

And there is where i'm stuck. When i try to catch this intersection point, the program gives me some random point, not on the intersection betwen the elements, but some random point around it. This leads to a greater problem, when i try to use the JOIN command to create a polyline it does not work.

Here is a screen of it:

Please, i need help.

Thanks for your attention.

Re: Problem with Snap Precision

Patchy — Mon, 21 Mar 2016 14:23:26 GMT

Increase the VIEWRES and see if it gets better.

Re: Problem with Snap Precision

rkmcswain — Mon, 21 Mar 2016 14:32:56 GMT

Never trust the graphical display.

After you snap to the desired point, if you're questioning the accuracy, then MEASURE the distance between the two objects (using NEA and PERP, or END and PERP, or whatever logical snaps fit the situation.) Make sure your units are out to max precision.

What coordinates are these objects at? Like near 0,0 or way out in space to 9 or 10 decimal places? (i.e.: 30010141251.12, 9547546582.12)

Re: Problem with Snap Precision

Anonymous — Mon, 21 Mar 2016 14:36:21 GMT

705000,0000;7529840,0000

Re: Problem with Snap Precision

Patchy — Mon, 21 Mar 2016 14:37:52 GMT

Zoom in, regen then use snap.

Re: Problem with Snap Precision

rkmcswain — Mon, 21 Mar 2016 14:47:16 GMT

When you're out to large numerical coordinates like that, accuracy can be an issue.

Not so much that the drawing is not accurate, but even if there is a 0.000000001 difference (which quite frankly if you're working in FEET or METERS is nothing) - can cause AutoCAD commands such as join to fail since it's detecting a gap or overlap....

Again, ignore what you see on the screen. You can zoom in all you want in certain cases and it will never "look" right, but the objects will be geometrically correct and be tangent, or coincident or whatever type of osnap you're trying to achieve.

Re: Problem with Snap Precision

Anonymous — Mon, 21 Mar 2016 14:57:42 GMT

Thanks bro