Author Topic: Strange symptom ... duplicate parts not duplicate (?)  (Read 703 times)

Offline EddyCurrent

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #15 on: April 02, 2024, 11:05:54 am »
It never crossed my mind that inside/outside would be the size difference answer, I've never had that issue because I always check the toolpaths with, View->Show toolpaths, before generating the g-code.

I found it impossible to try that with the file attached because it was so slow, due to the number of points, and when trying to apply Arc Fit to all of it I ended up with a Ctrl+Alt+Del situation.

CamBam is not the only software that works with a negative scale value, any CAD applications I've used and also Unity game engine do.

@David,

Maybe yout Numeric Move plugin could add a mirror function where it reverses any open polylines etc. in the mirrored items ?
« Last Edit: April 02, 2024, 11:10:01 am by EddyCurrent »
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Offline Chopper

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #16 on: April 02, 2024, 14:04:06 pm »
dh42 - Thank you for an eminently clear and concise explanation. All of the argle-bargle plaguing me over the last few days now is much less murky. I now know to pay a lot more attention to my "raw" drawings, and how to deal with potential problems. I know to enable the cut-width parameter (had I done so I likely would not have missed the "out-of-position" tool path, since the TP would have been much more visible). I now know that "-100% resize" really means "flip and move", re-sizing being only a part of the function, and perhaps most importantly I now know how a line (polyline) can, within the context of CamBam, have two sides and why that is important. Edit: I should also mention the polyline "open/close" parameter - I am not exactly clear on why CB thinks a polyline is closed if it is indeed open -- but I will always check it going forward.

As I said at the start of this thread, CAD is not a strength of mine, but I am now more capable than I was a few days ago -- thanks largely to you, but also to the others who took the time to illustrate and explicate. I am grateful.

Be well.

« Last Edit: April 02, 2024, 14:14:45 pm by Chopper »

Offline dh42

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #17 on: April 02, 2024, 20:58:29 pm »
Hello

Quote
I found it impossible to try that with the file attached because it was so slow, due to the number of points, and when trying to apply Arc Fit to all of it I ended up with a Ctrl+Alt+Del situation.

Strange, for me it is almost instantaneous.  ??? ...maybe dependent of the tolerance value ?

the video is in real time.

Quote
It never crossed my mind that inside/outside would be the size difference answer

Lol, same for me, and I SEE IT, but in my mind all was undersized of 5%, not only the outlines ... and I only measure features on the pocket not on the outlines !!

For mirroring, I rarely use the transformation matrix, the mirror tool is more user friendly ;)

https://cambamcnc.com/doc/1.0/cad/transformations.html#mirror

++
David

« Last Edit: April 02, 2024, 21:02:13 pm by dh42 »

Offline Bob La Londe

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #18 on: April 02, 2024, 21:21:58 pm »
I use the transformation matrix on the operation all the time, but rarely on the geometry.  This way I have less geometry in the CB file slowing CB down. 

Since I make a lot of molds this is very handy for me.  Cut this.  Now cut a mirror image of this. 

I use the heck out of the negative scale in this manner. 
Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

Some Stuff I Make with CamBam
http://www.CNCMOLDS.com

Offline dh42

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #19 on: April 02, 2024, 21:53:08 pm »
re

note that the "arc fit" alone on the original polyline do not give a suitable result.

on the pictures, in yellow, original polyline with stairs. arcfit 0.05 (cyan) and 0.005 (green) and poly smooth 0.02 (red)

the smoothed polyline is without any arcfit, I superimposed the points of the polyline. .. seems it is really the better way for lines with stairs ..

++
David

« Last Edit: April 02, 2024, 21:56:17 pm by dh42 »

Offline dave benson

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #20 on: April 03, 2024, 02:29:35 am »
Chopper

The issues you are seeing (your polylines having a lot of random noise) is
because if the method\techniques used to generate them from the original image.

No amount of fiddling around in CB will fix this completely,

The Idea is to present CB with nice clean polylines at the beginning of the drawing process.

In the pics you can see that I have downloaded a random picture of a shelf bracket and
(In Inscape) used the trace bitmap function and the exported the file as a dxf .
This method generates very clean CB ready polylines.(you can also export as SVG too)
If I was cutting this file, I would replace the two long straight polylines with new
ones just to make sure that they are perpendicular to each other.

While I was at it I noted the toolpath generation time of the original and new geometry
and the mop for the original file took 961 times longer to generate the toolpath even though it was 25% shorter.
If you are doing 2D work, long generation times are a good sign that somethings
amiss.
If you post the original image file that the polylines were generated from then I can tell you if it's a good candidate to use, or if not why.

Dave

Offline Chopper

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #21 on: April 03, 2024, 15:16:07 pm »
Dave:

Appreciate your comments. Did you mean "Inkscape" instead of "Inscape"?

Offline dave benson

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #22 on: April 03, 2024, 23:55:54 pm »
Yes Inkscape, If you don't have it, it's a Free  scale-able vector graphics program that
has been around for a long time now and is quite useful for this kind of image manipulation
for CB.

Like anything, it takes a bit of time to get to grips with the options in the trace bitmap function
as there are lot of them, but for the most part, the first tab will be all you need  'single scan'
I 'use multi scan' sometimes for other work not related to CB.

This particular method, snipping a pic and processing through Inkscape is usually done
with engravings not objects that require tight tolerances, on your object I would check that the
lines making the shelf and back (where it abuts the wall) are perpendicular.

I think that with this part I would consider importing the image into CB and hand trace over
the original lines or alternatively use Inscape or Freecad to do the same.

If your not wedded to making a original design for your shelf brackets, then whilst perusing
the interwebs for a image of a bracket, I came across quite a few repositories that had bracket
designs (some free and some paid for) that would be ready for CB to work with, just apply
mops.

Dave

Offline Chopper

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #23 on: April 04, 2024, 00:11:39 am »
Good information, Dave.  I have looked at Inkscape in the past but it seemed a bit too robust for my purposes (read: steep learning curve!) I am just a hobbyist with a homebuilt CNC router, Based on your comments, I may give it another look, because I filch most of my patterns from images in books and magazines, and it sounds like the Inkscape approach to get clean drawings/patterns could  be mighty handy. Thanks again for your suggestions.
« Last Edit: April 04, 2024, 00:16:06 am by Chopper »

Offline dh42

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Re: Strange symptom ... duplicate parts not duplicate (?)
« Reply #24 on: April 04, 2024, 20:24:23 pm »
Hello

Quote
I think that with this part I would consider importing the image into CB and hand trace over

Yes, this is what give the best results, but take some time (but not necessary more than trying to "repair" digitized lines)

I add a small example in attachment (sorry, in french)

++
David