Author Topic: Prolem joining polyine  (Read 5117 times)

Offline tonybraz

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Prolem joining polyine
« on: October 19, 2023, 15:14:43 pm »
Hi I have drawn a Rc car chassis and cannot join the polyline, Layer 1 which is the outer edge of chassis. I have drawn other chassis and have not had a problem, could someone explain what I have done wrong.

Cheers Tony

Offline lloydsp

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Re: Prolem joining polyine
« Reply #1 on: October 19, 2023, 17:35:22 pm »
The first segment of polyline 147 is reversed so the endpoint cannot match the other polyline.  Explode 147, and ensure that all segments of it are continuous in one direction around it.  If a segment is in the wrong direction, simply 'reverse' it.  Do so for all segments (perhaps in both polylines).  I suspect you drew those 'piece by piece', and did not attend to the direction when you were drawing them.

Lloyd
« Last Edit: October 19, 2023, 17:38:01 pm by lloydsp »
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Offline dh42

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Re: Prolem joining polyine
« Reply #2 on: October 19, 2023, 17:37:08 pm »
Hello

There are many segments that overlap and/or go back. Some can bee seen when you look on the polyline, they looks wider when the lines overlaps (see picture). This also can bee seen if you zoom on the polyline. Your drawing needs a lot of cleaning !

Overlaps exist also on the other features.

Select your polylines, explode them, and remove the lines that overlaps, then join again.

example:


Also, have a look to the "remove overlap" function (edit/polyline) that can also help to solve this kind of problems.

https://cambamcnc.com/doc/1.0/cad/edit-polyline.html#remove-overlaps

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David

« Last Edit: October 19, 2023, 17:39:58 pm by dh42 »

Offline dh42

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Re: Prolem joining polyine
« Reply #3 on: October 19, 2023, 19:52:46 pm »
Re

Your drawing, cleaned on all shapes, is in attachment. You should be more precise when you draw, there was a lot of lines that do not end up where the next start.

You can have a look on this

https://cambamcnc.com/forum/index.php?topic=1624.0

++
David

Offline tonybraz

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Re: Prolem joining polyine
« Reply #4 on: October 20, 2023, 13:48:22 pm »
Thank you for your reply, I usually draw in Qcad and open Cambam to convert to nc file. Would it be better to do the whole thing in Cambam.

Cheers Tony

Offline lloydsp

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Re: Prolem joining polyine
« Reply #5 on: October 20, 2023, 13:57:26 pm »
Tony, my inclination is to think it was the order in which segments were drawn and joined in Qcad, not the package itself -- except for the issue that CamBam would not have permitted overlapping, duplicate, and mis-joined segments to be joined, in the first place.

So, in answer to your question -- if Qcad permits such things, I think you would be better off drawing such elements in CB.

Lloyd
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Offline dh42

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Re: Prolem joining polyine
« Reply #6 on: October 20, 2023, 17:00:10 pm »
Hello

Yes, and you must think that the "join" function in CamBam is not a "magic" tool that repair lines that do no join correctly, in the attached picture, if you have the lines that cross, as on the top of the picture, when joining, cambam will not cut the ends so they end to the same point, but it will add a small segment to join the ends (the red line), so this can give lines with "nodes" as on your drawing.

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David

Offline lloydsp

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Re: Prolem joining polyine
« Reply #7 on: October 20, 2023, 17:39:45 pm »
Because I use endpoints as 'drawing nodes', I've not had that happen, David.  Does CB warn you with some sort of exception message when that occurs?

Lloyd
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Offline dh42

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Re: Prolem joining polyine
« Reply #8 on: October 20, 2023, 20:07:31 pm »
Quote
Does CB warn you with some sort of exception message when that occurs?

Not at all ; if the "tolerance" value given for "join" is < to the distance between the end points of the 2 lines, nothing will be joined (no line added)

This video show also what happen if 2 lines overlaps and if  the "join" function is used, that can explain some back track on a drawing.



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David
« Last Edit: October 20, 2023, 20:17:58 pm by dh42 »

Offline lloydsp

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Re: Prolem joining polyine
« Reply #9 on: October 20, 2023, 21:18:38 pm »
Ah, thanks.  I always join lines with a very small tolerance.  If they do not join, I immediately am aware of an endpoint issue.

Lloyd
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Offline Garyhlucas

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Re: Prolem joining polyine
« Reply #10 on: October 20, 2023, 21:40:43 pm »
When you see lines that don’t end at other lines it usually indicates someone is not using snaps, which is absolutely important. Most cad programs have a fillet function. I use it all the time with a zero radius because it will trim both lines to the exact intersection point.
Gary H. Lucas

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 http://a-little-business.blogspot.com/

Offline tonybraz

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Re: Prolem joining polyine
« Reply #11 on: October 21, 2023, 21:04:32 pm »
Thank you for your help, yes the drawing was very messy but I was reverse engineering the chassis. So went and followed the suggestions and it worked great.

Cheers Tony

Offline EddyCurrent

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Re: Prolem joining polyine
« Reply #12 on: October 22, 2023, 09:47:13 am »
Maybe give this open source 2D CAD a try, https://librecad.org/

From the web page,

"LibreCAD started as a project to build CAM capabilities into the community version of QCad for use with a Mechmate CNC router."
Filmed in Supermarionation