topic Re: Offset bug? in AutoCAD Forum

Offset bug?

wbdehaan — Thu, 10 Sep 2020 07:30:30 GMT

Hi,

in AutoCad I experience strange behavior. when I offset the black polyline 6mm to the outside, and then offset the newly created (blue) polyline 6mm to the inside, it should be on the black, but i get the pink polyline, and this polyline is also reversed (drawn clockwise instead of counterclockwise). Is this a bug or am I missing something?

when I move the polyline it sometimes offsets correctly, so I think it is a rounding issue.

(the reason this is a problem for me, is that i wrote an automated millingprogram for a CNC woodworking station inside AutoCad, and this polyline is milled in the wrong contour, but also on the wrong side.)

(I use AutoCad 2021 and windows 10)

kind regards,

Woter

Re: Offset bug?

ennujozlagam — Thu, 10 Sep 2020 07:43:30 GMT

i don't find any issues. offset as expected. try to install latest updates from autodesk and try switch off your GRAPHICSCONFIG and see if helps. thanks

Re: Offset bug?

vinodkl — Thu, 10 Sep 2020 08:07:25 GMT

Hi,

This is caused by not closing the polyline when it was drawn(I mean not to make the endpoint of the polyline to meet the starting point of the polyline but not using the option "close" while drawing the polyline to close the polyline completely)

Try to "EXPLODE" the polyline and then use the command "JOIN" to the lines and then try using offset. It will work as you expected🙂

Re: Offset bug?

wbdehaan — Thu, 10 Sep 2020 08:12:32 GMT

Hi,

thank You for Your quick response, I disabled graphicsconfig, we have the latest version of AutoCad2021, but it also happens in AutoCad 2020 and 2019. I added a video

Re: Offset bug?

wbdehaan — Thu, 10 Sep 2020 08:21:29 GMT

Thanks for Your answer,

the problem for me is that my program/macro passes several thousands of polylines automatically, and I need to rely on the offset feature in autocad, and cannot check every polyline.

kind regards,

Wouter

Re: Offset bug?

ennujozlagam — Thu, 10 Sep 2020 08:25:58 GMT

you wrote

the problem for me is that my program/macro passes several thousands of polylines automatically, and I need to rely on the offset feature in autocad, and cannot check every polyline.

in the command prompt type BPOLY and pick inside it will create a boundary polyline erase the existing line and try to offset a new boundary line and see if helps. thanks

Re: Offset bug?

ennujozlagam — Thu, 10 Sep 2020 08:41:01 GMT

i really don't understand why do you have this problem at i don't see any problem at all. it could be you have 3rd party plugin hindrance to your command offset. thanks

https://autode.sk/2FmeFEc

Re: Offset bug?

cadffm — Thu, 10 Sep 2020 09:34:09 GMT

@ennujozlagam

In your screencast we can see the same shape! but only as preview.

I can not check the polyline(acad not available now), but i would check:

Is this pline part a bulge?

The position in WCS, is it the same at 0,0,0 wcs?

It's not the first time you can see this if the size/length os very small or high.

Bulges which are near to be a straight are always a problem.

But in this case the wrong this is to have a bulge, it should be a line segment(or).

Re: Offset bug?

ennujozlagam — Thu, 10 Sep 2020 10:31:50 GMT

you can download the attached file from the OP. i used the same file for my screencast. thanks

Re: Offset bug?

pendean — Thu, 10 Sep 2020 13:58:42 GMT

Your shape changes with the first offset, so it is not the same as the original anymore, so the second offset works from the new shape, not the original shape.

It appears that line at the end of your arc is lost at the second function. Not much you can do about it.

Tested in R2021.1 and R2019.1.2 here, same results as you.