Author Topic: Detecting a D hole edge as a single polygon  (Read 2081 times)

Offline ajawamnet

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Detecting a D hole edge as a single polygon
« on: June 13, 2019, 20:41:07 pm »
For some reason CAMBam NOT will generate a single polygon from  edge detection of the attached STL file. Even after going thru the machinations of joining the tiny segments up I still can't get a Profile toolpath to generate.

Visual mill has no problem with the same STL file detecting the D hole edge as a single entity and generating a profile tool path.  See screen shot also attached

Also it'd be nice if you could edge detect a single face in the XY plane.
« Last Edit: November 01, 2019, 22:29:05 pm by dh42 »

Offline dh42

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Re: Detecting a D hole edge as a single polygon
« Reply #1 on: June 13, 2019, 20:49:15 pm »
Hello

Just after you've done the edge detect, remove the 2 vertical lines in the hole, then, with all polylines selected, change the value for "closed" to "false" for all polylines in the property grid ; now you can "join".

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David

Offline dh42

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Re: Detecting a D hole edge as a single polygon
« Reply #2 on: June 13, 2019, 20:55:06 pm »
If your CAD software is able to do it, and if you're using Cambam V1, you can export to STEP ; STEP files give a better way to get the outlines (they are done when importing the STEP file) and it also use "true" arcs instead a bunch of small segments as with STL.

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David

Offline ajawamnet

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Re: Detecting a D hole edge as a single polygon
« Reply #3 on: June 13, 2019, 21:02:03 pm »
I tried the STEP out and for some reason the display in CB is funky - see attached

I'm using an OpenGL card and no matter what I set the options to it's nasty..

Offline ajawamnet

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Re: Detecting a D hole edge as a single polygon
« Reply #4 on: June 13, 2019, 21:04:58 pm »
Cambaqm works with the Cartesian coordinate system.
So it is clear which direction is the positive one.

look at giyf.com

ralf

No not really... if you just go by the colored lines.

Offline dh42

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Re: Detecting a D hole edge as a single polygon
« Reply #5 on: June 13, 2019, 21:09:20 pm »
Quote
I tried the STEP out and for some reason the display in CB is funky - see attached

Hum, yes, it's a know problem with small values (appears mostly with inches) ; currently STEP import has a fixed resolution value and it give sometimes bad results with the display ; adding a resolution value is on Andy's todo list ...

The display is wrong, but I guess that the edge lines are OK ?

can you share the step file ?

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David

Offline dh42

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Re: Detecting a D hole edge as a single polygon
« Reply #6 on: June 13, 2019, 21:19:36 pm »
Re

I just have a try ; the surfaces are bad, but the outlines are OK and they can be used with 2D machining operation.

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David

Offline ajawamnet

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Re: Detecting a D hole edge as a single polygon
« Reply #7 on: June 13, 2019, 21:22:39 pm »
So it appears that the step file comes in at some weird scale... see attached. Left is STL right is STEP


Same STEP comes into other CAD tools at the correct dimension of 2.34 in...

Offline ajawamnet

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Re: Detecting a D hole edge as a single polygon
« Reply #8 on: June 13, 2019, 21:26:12 pm »
Quote
I tried the STEP out and for some reason the display in CB is funky - see attached

Hum, yes, it's a know problem with small values (appears mostly with inches) ; currently STEP import has a fixed resolution value and it give sometimes bad results with the display ; adding a resolution value is on Andy's todo list ...

The display is wrong, but I guess that the edge lines are OK ?

can you share the step file ?

++
David

Yea - in the ZIP When I went to attach the STEP file the forum gave me some warning about not allowing STEP extensions then kicked me off to Google...


Offline dh42

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Re: Detecting a D hole edge as a single polygon
« Reply #9 on: June 13, 2019, 21:56:27 pm »
Ah ah, very strange.

I do the same with SW and no problem, both STL and STEP shapes are the same size in CamBam (but I work in mm in SW), but I get the same error with your file ... it seems that there is an import bug with inches  ... if I creates a shape in inches on SW, I get the same size error.

seems that shapes exported in inches are underscaled from 39.370 time ...  ???

I'll add this in the bug list.

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David

Offline ajawamnet

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Re: Detecting a D hole edge as a single polygon
« Reply #10 on: June 13, 2019, 22:52:30 pm »
Wow - when I changed to MM on SW it came into CB nice...

Weird tho - when I go to use it in an Inches setting in CB, the units for depth, tool diameter offset,  and everything seem to be in mm still.

And weirder still - if set to a Profile -Inside, it cuts the STEP arc inside but the lin outside. IF you  change the MOP to Outside it flips it around - cuts the line inside and the arc outside...

See attached CB file and jpg. Not the 0.015 depth looks like 0.015mm even tho the job is set up for inches...

Oh - as to CNC Ewok - I've done over 3,000 jobs on my machine over the last 20 years using Visual Mill.. I was one of Solidwork's first customers back in 1995. I still have my 1996 install CD (I have no idea where the 1995 one is)

http://ajawamnet.com/
http://www.ajawamnet.com/ajawam3/swarf/swarf.htm



« Last Edit: June 13, 2019, 22:55:33 pm by ajawamnet »

Offline dh42

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Re: Detecting a D hole edge as a single polygon
« Reply #11 on: June 13, 2019, 23:01:19 pm »
Quote
And weirder still - if set to a Profile -Inside, it cuts the STEP arc inside but the lin outside. IF you  change the MOP to Outside it flips it around - cuts the line inside and the arc outside...

All lines of the profile must be joined.

http://www.cambam.co.uk/forum/index.php?topic=1624.0

Quote
Weird tho - when I go to use it in an Inches setting in CB, the units for depth, tool diameter offset,  and everything seem to be in mm still.

unit must be changed BEFORE to create the MOP (machining operations) ; nothing is changed in existing MOP.

changing the units do not automatically resize the drawing ; you can use the mm>inch or inch>mm buttons in the scale window.



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David
« Last Edit: June 13, 2019, 23:08:57 pm by dh42 »