topic Trim multiple instances of regularly occurring lines at intersections in AutoCAD Forum

Trim multiple instances of regularly occurring lines at intersections

Anonymous — Wed, 07 Jul 2021 23:39:20 GMT

Hi everyone,

I'm looking for a solution to speed up a task that takes a lot of time.

The shape of the outline I have is arbitrary and has an internal repeating pattern, typically straight lines (See screenshot Design_sample). For machining purposes, I need to delete the small intersecting lines where the pattern meets the boundary. Currently I do this individually around the perimeter of the design using the trim tool which can take a long time. I've tried using break and extrim but I haven't been able to find an adequate solution using these tools.

I'm hoping that there is a way to speed this process up. I have several ideas of how it could be done but so far I have not found a way to do them.

My first idea was to create another series of lines that pass through each point that I need to remove. I was hoping that I could use these lines as fences and they would trim everything that they touch but I haven't been able to make this work (see screenshot Trim_touching).

Another idea was to instantiate my cursor along a length so that I only need to drag the fence across one length and it would be replicated as I do so, though I'm not sure where I would start with this idea.

My last idea was to use the repeating pattern itself as the fences and try to trim within that pattern (See screenshot Multiple_fences).

Thanks in advance.

Regards,

Corey

Re: Trim multiple instances of regularly occurring lines at intersections

Patchy — Thu, 08 Jul 2021 02:17:12 GMT

Have you tried the command EXTRIM?

Re: Trim multiple instances of regularly occurring lines at intersections

Anonymous — Thu, 08 Jul 2021 02:47:14 GMT

Hi Patchy,

Yes I have tried extrim. It only allows you to select one line as a fence and then ask which side of the fence you'd like to trim, unless there is some other way to use extrim that I'm unaware of.

Re: Trim multiple instances of regularly occurring lines at intersections

Patchy — Thu, 08 Jul 2021 02:54:17 GMT

Is the blue line a polyline ? if it is then it will trim every lines outside or inside of it.

Re: Trim multiple instances of regularly occurring lines at intersections

Anonymous — Thu, 08 Jul 2021 03:11:08 GMT

Perhaps my original post was not clear but I am trying to trim the blue line not use it as a fence. I need to trim the small length of the blue line between each individual segment like in the screenshot attached below.

Re: Trim multiple instances of regularly occurring lines at intersections

Patchy — Thu, 08 Jul 2021 03:20:10 GMT

There are a few autolisp that break a line at intersections (one of them called BREAKALL.lsp https://www.cadforum.cz/en/download.asp?fileID=682), you can find them within the autodesk search or web search.

After break the blue line then you can use QSELECT to select line length less than a certain distance, then delete them with one click.

Re: Trim multiple instances of regularly occurring lines at intersections

Kent1Cooper — Thu, 08 Jul 2021 11:06:39 GMT

[... never mind ... I misunderstood before I read Message 5.]

Re: Trim multiple instances of regularly occurring lines at intersections

Anonymous — Fri, 09 Jul 2021 00:47:30 GMT

Thank you Patchy,

The BREAKALL method you suggested works very well in this instance, but not perfectly because the blue lines vary in length as the angle of intersection changes meaning that the QSELECT-delete method can capture most of the lines I need to delete but not all of them. The only problem is if I increase the range of line lengths to include all the geometry I'd like to delete, I may select some geometry that I'd like to keep (smallest line length is 5mm and largest was 15mm), but this is a minor issue as most lengths will be around 5mm.

There may be a more elegant solution out there but using this method I can safely delete at least 80-90% of the geometry I'd like to remove with one click.

For anyone wondering, I used BREAKALL and a break gap of 0, then QSELECT->Polylines->Length->less than 9mm. Then click delete.

Thanks again.