Nodes

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JodiB
Posts: 19
Joined: Wed Mar 08, 2017 11:42 pm

Nodes

Post by JodiB »

How's it going? Oh the nodes, nodes, nodes, nodes! There's one thing I hate! All the nodes, nodes…..
A little holiday humour. I'm having an issue with all the nodes being added into Sheetcam. I'm using CorelDraw X8. The image is exported as an SVG or DFX into Sheetcam and as you can see bellow a lot of nodes are added.

The lines are not cutting smooth on my plasma table and are quit choppy.

It would seem that from time to time on a cut the torch hesitates on a node to figure out its next move.

I wasn't having this problem a few months ago and this issue has just cropped up. I'm spending way to much time filing.

Any ideas?
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Les Newell
Site Admin
Posts: 3661
Joined: Thu May 11, 2006 8:12 pm

Re: Nodes

Post by Les Newell »

The problem is that you have a lot of non-circular curves. G-code only understands circular arcs and lines. SheetCam does it's best to try to convert the curves to arcs where they are close. Go to Options->application options->drawing import and experiment with the arc fitting tolerance. Increasing the value will make arc matching more aggressive and reduce the number of nodes, though it will sacrifice accuracy. Note this setting only takes effect when you load a drawing so you need to reload the drawing each time you change it.
JodiB
Posts: 19
Joined: Wed Mar 08, 2017 11:42 pm

Re: Nodes

Post by JodiB »

Thank you for your reply Les...much appreciated. I've been at this for over 3 years so believe me, I've played with the drawing import settings many times over. Initially I used coreldraw x8, sheetcam and mach3. For over a year now, I've been using coreldraw x8, sheetcam and candcnc. I've had my fair share of cut issues with both types of software, but for some reason, they've been getting increasingly worse. I got a new laptop 3 months ago with latest version of Windows 10...ever since, my gcode has been off. The torch visibly pauses several times throughout the cut, the cuts are choppy and my corners are all rounded - I've tried changing the settings for loop sharp corners, but nothing works. I've literally spent hours trying to get these problems figured out with no success. I downloaded the latest sheetcam update about a week ago...prior to this, my drawings would show hundreds of added nodes when imported into sheetcam. Since the update, my drawings are now completely covered in nodes. Any advice you can offer would be greatly appreciated.

In your opinion, Les, what drawing software and file format are most compatible with sheetcam? Even though my drawings are completely clean of any non-necessary nodes prior to putting into sheetcam, I've been told that they are made up of non-circular curves and segments. Is this normal? Does everyone that uses coreldraw experience the same issues? Is it the way I'm drawing? I've used SVG and DXF...which is better and why? Sorry for all of the questions...I just need some clarity on all of this once and for all.

Thank you Les!
Jodi
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Les Newell
Site Admin
Posts: 3661
Joined: Thu May 11, 2006 8:12 pm

Re: Nodes

Post by Les Newell »

HI Jodi,

Sorry for the delay in getting back to you. The file format shouldn't make much difference. Arc detection and node reduction is done after the drawing file is loaded. Look at your drawings. They contain lots of flowing curves. They look good but g-code has no way of cutting them directly. It can only do straight lines or circular arcs. Unfortunately few of the curves in your drawings are perfectly circular so SheetCam has to break them up to cut them.
Jolbas
Posts: 88
Joined: Sat Feb 02, 2019 8:59 am

Re: Nodes

Post by Jolbas »

JodiB wrote: Fri Dec 27, 2019 6:08 pm they've been getting increasingly worse.
Is there a possibility it's related to this fix? If the drawing is big enough to disable the error checking.
viewtopic.php?f=2&t=8063&p=26199&hilit= ... ime#p26224
robertspark
Posts: 257
Joined: Thu Feb 26, 2015 12:11 am

Re: Nodes

Post by robertspark »

JodiB wrote: Fri Dec 27, 2019 6:08 pm I got a new laptop 3 months ago with latest version of Windows 10...ever since, my gcode has been off. The torch visibly pauses several times throughout the cut, the cuts are choppy and my corners are all rounded
does Mach3 run on the new laptop?

how are you running mach3? (parallel port, smooth stepper, USB, ethernet, other motion controller???)

is mach3 set to run in constant velocity mode? G64 (or via the config tab).

what lookahead are you running? (how many lines)

if you are running a motion controller, (ESS, etc) have you considered increasing the buffer?

what units are you running in?

There is a setting within sheetcam post processor:

Code: Select all

   minArcSize = 0.05 --arcs smaller than this are converted to moves
that you way want to adjust relative to YOUR setup.....
to give you an idea.... 0.05mm is ~20 thousands of an inch..... The smallest step on my plasma cutter is 0.05mm, also the best kerf I can get is ~0.7mm (0.0275")...... not a lot of point worring about small arcs and moves, as all they will do is create loads of lines of code

likewise .... under Application Options >> Drawing Import there are another load of settings that probably want to be customised to your setup (considering your X and Y axis step sizes + machine kerf, which while great for milling and router applications may not be quite so good for a blunt instrument such as plasma.... (you decide what works for you)....
2020-01-03 14_20_19-SheetCam TNG Development - Untitled.png
2020-01-03 14_20_19-SheetCam TNG Development - Untitled.png (19.73 KiB) Viewed 2506 times
And finally..... how are you exporting from your drawing application to sheetcam (what scale are you using as this may affect the number of nodes....)

Oh and before I forget Mach3 can sometimes be sensitive to graphics card drivers / memory and this may (on big files) cause a slow down or hesitation..... check you have the latest drivers for your laptop loaded .... even though its new the drivers on it and the bios firmware may be out of date leading to memory allocation issues that may have been fixed in later driver updates. {it may be a long shot but worth ruling out).
robertspark
Posts: 257
Joined: Thu Feb 26, 2015 12:11 am

Re: Nodes

Post by robertspark »

bit of explanation on the options from the Sheetcam help file (tap F1 when in the screen and it should pop up with the explanations {thanks Les})
2020-01-03 14_59_27-Help_ Drawing import.png
2020-01-03 14_59_27-Help_ Drawing import.png (43.51 KiB) Viewed 2503 times
PointBlank
Posts: 1
Joined: Thu Jun 18, 2020 6:07 am

Re: Nodes

Post by PointBlank »

JodiB did you ever find a solution to your problems? I am have the same issues with Coreldraw and SheetCam. Please let me know. Thanks!
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