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How to solve an open chain problem

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18 replies to this topic

#1
Chris Flint Two Ft Pty Ltd

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G'Day all,
I am having a heck of a time with an open chain.
I have what to me looks like a completely closed boundary, which I want to pocket to remove the material to a depth of 6mm.
I have :Modify, Trim etc.etc to ensure all looks ok and is trimmed together.
If I select delete Chain the whole thing deletes.
But when I Toolpath, Pocket, Chain, I get the
"Branch Point reached, end here" with the cursed red arrow.
I have tried to re-trim all, I have tried to join, I have tried Squash, I have told it to ignore depths.
What am I missing.
This is one contour in amongst 20 or so all of the others do not have the same problem.
Where to from here.
Thanks
chris f

#2
Matt Berube at Ferron Mold

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can you mess with the chaining tolerance under options in the chaining dialog ?

#3
Chris Flint Two Ft Pty Ltd

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I have tried that even to the extent of re creating this part of the geometry from a workable one, but it says "overlapping entities" and I am damned if I can find them
chris f

#4
Kannon

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can you try the findovlp chook to catch it?

#5
Bill

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+1 to Kannon. Also, are they splines by chance?

#6
flatwoods

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Have you tried ALT E select chain and then see if it will contour it ?

#7
MIKE_B

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Did you make sure to check C-plane and not 3-D in your chaining dialog box? This has got me a couple of times.

#8
Gary

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I like to squash to just above my part like to .01 or something so in an iso view it is easier to separate the problem chain from the rest. If you can post it to the ftp I will try to help.

#9
Chris Flint Two Ft Pty Ltd

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Thanks for the assistance, I was unaware of the overlap chook I have now used that and will keep it in my armoury for the future, good one thanks.
I checked the 3D and no I am in T.
ALT E is another great help as it isolates the problem and in amongst the lines it is very difficult to remember which one it is, thanks for that one too.( got a bit of a worry when I could not get the drawing back so thought "just press alt e again" and voila there it was).
And yes they are mainly splines that are giving me a problem.
What I have done to correct it and managed to stop the issue was to "Fillet" the corner with a 0.5mm radius this seems to join the lines and splines and allow me to continue completing the toolpaths 0.5mm on a 2800mm board is not going to be a problem.
But I still do not understand why the trim feature does not "join" the open boundaries,( strait lines to splines), perhaps I just do not know which trim function to select for the best effect.
But to all many thanks for the input I am indeed indebted to this forum.
chris flint

#10
Dwain Dyer @ Advanced Machining

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Have you tried the Join function?

V9= Modify, join

X= Edit, join

Also

Delete, duplicate enities

works well to solve this behavior sometimes.

#11
Chris Flint Two Ft Pty Ltd

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Yes I did try join and by the way sorry to all. I am in V9 latest release.( Got X but cannot use it as it does not yet support ART, which is my main use program).
I have found the join operation to be frankly hopeless, in that whenever I have used it it did not work and gave me some lame explanation as to why it couldnt, splines mixing with lines maybe is the issue.
Anyway good news I found the problem.
Whe I zoomed up to about 1 million percent there was a tiny squigle of a line across one of the lines, tried to delete it, would not go away, so I deleted the line and there it still was, tried to chain select it and could not, so I "delete, window" and then it dissapeared.
Redrew the line and now all is happy, how one is supposed to find these problems quickly is a mystery to me.Surely MC could put in a chook the "creates geometry in problem areas" and then lets you select it if you are happy with the suggested outcome, more for the wish list.
Anyway many thanks to all I learnt a heck of a lot from the replies to this question.
regards to all.
chris flint

#12
Midwest

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Another problem can be duplicate entities.


"cursed red arrow"

Zoom into this area to find the problem.

In v9 I have used screen endpoints to highlight the endpoints of the splines,arcs,lines then use you mouse to lighlight the splines,arcs,lines and look for overlaps, gaps.


Another way I have found little problem areas is to change color by chaining, them do a Alt E with the original color and see if there is anything there. I have found them so tiny the only way to see them easily is to use screen endpoints, then they are easy to see. You can also use screen statistics.

HTH

graemlins/cheers.gif

#13
JParis

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I would zoom in very closely on the apparent "bad" area. I have found in X for some strange reason that sometimes lines don't quite trim together. It's only happened to me twice but I have had to go in and trim very small breaks.


I haven't figured out why it happens yet.

#14
Chris Flint Two Ft Pty Ltd

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I forgot the screen endpoint function.
More to remember.
thanks
chris f

#15
Tony@St.Charles Mold

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Sometimes I dont have time to deal with this so I start a new level and create edge curves
and piece the whole thing together myself.
MC understands 100% its own Geo and will chain like a banshee

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#16
Thad

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Anytime you chain something, your chain should begin where you click. If it doesn't, the place where the chain begins is your (or at least one of) your problem areas. Zoom way in and have a look. Move your mouse over it. Sometimes you'll see autohighlight flicker, which means you have entities on top of one another. Sometimes there is a small line/spline segment overtop of the one that you want. It's enough to cause MC to find a branch point. Try deleting the segment and repaint. If it reappears, you've found the problem.

Analyze chain works nice too to find the problem area. I've yet to have one that I can't figure out.

Most times, if not all, to trim splines they must overlap. They won't extend to trim like lines will. You'll have to extend them first, then go back and trim them.

graemlins/cheers.gif

Thad

#17
Chris Flint Two Ft Pty Ltd

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Tony I am not sure how to "create edge curves"
On a new drawing, I would like to copy the geometry and get a clean copy in MC.
I imported this new job from DXF the piece is 20 X 20 inches and when I went "screen endpoints" it highlights about 300 endpoints.
Which could take all day to sort, surely the import function is a bit better than that, I imported a DXF from a customer that emailed me the DXF.
Is there perhaps a switch I need to activate to get the drawing into MC with "less" endpoints, overlaps etc, as this makes me think the import function is not real flash?
chris f

#18
greg williams

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Can you get the customer to send you an Iges File instead of DXF?

#19
Midwest

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quote:


Anytime you chain something, your chain should begin where you click. If it doesn't, the place where the chain begins is your (or at least one of) your problem areas.

Getting a file from a customer for engraving is usually where I have seen the problems you are having. All the tips above will help you solve your problems, the more you work with the problems the better and faster you will become.


quote:


I went "screen endpoints" it highlights about 300 endpoints.

Look at the problem area's............not the whole 20 X 20 wink.gif


Also 300 is a lot smaller than some of the engraving I have had to work on, but I only worked in the problem area's


You also talked about DXF, are they little lines if so try coverting them to splines, your tool path will generate faster then also.


The FTP is your next choice, I'll be busy until Monday noon, but someone else will probable help you B4 I can look at it.


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