Using QCADCAM for Engraving Text

Discussions around the CAM Add-On of QCAD version 3

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Using QCADCAM for Engraving Text

Postby cmcgrath5035 » Fri Apr 18, 2014 2:18 pm

I am still running 3.4.6Pro on openSUSE Linux 13.1

My current project is the design of text lettering plates to be engraved in multi-layer plastic.
I used the Cyrillic_II single stroke font.
I have run several iterations and generated GCode for my machine, with generally good results (some early machine issues, not quadcadcam)

I have two resulting observations/questions from this exercise:
1. I find the log file generated during the export process to be useful in understanding the background processing going on by CAMexport.
Is there a way to have the log file named the similarly as the .nc file? For example, lets say my my design file is design.X.Y.dxf (majorversion X, minor versionY).
The default name chosen by Camexporter seems to be design.X.nc, but I am able to modify that during the dialog after setting the GCode parameters. A typical name I might choose while experimenting is design.X.Y_comment.nc. That works OK and the GCode file gets saved.
But the log file always come out design.X.log. My workaround, if I want to save it, is to use the system rename capability.
Is there a more automated way to have the files names chosen_name.nc and chosen_name.log ?

2. GCode generated for Fonts: From watching the machine work, or now by running the CAM simulator, it is clear that segments that make up the font characters are not affected by the selection of "optimize paths" in the Gcode parameter setup. This results in a lot of extra machine motion when drawing for example, an "O". Rather than drawing 8 segments continuously, some segments are drawn CW, some CCW. I am guessing this is buried in the font definition tables.
I just ran an experiment - selected all text in the design file, then Modify-Explode to convert it to paths. The resulting GCode file is much larger, but viewing the simulation appears to be what I call much smoother machine motion - for example my "O"s are "move to start-draw O continuously CW-move to next letter.
Is there a better way to achieve this result?

Thanks
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Re: Using QCADCAM for Engraving Text

Postby andrew » Fri Apr 18, 2014 9:19 pm

cmcgrath5035 wrote:1. I find the log file generated during the export process to be useful in understanding the background processing going on by CAMexport.
Is there a way to have the log file named the similarly as the .nc file? For example, lets say my my design file is design.X.Y.dxf (majorversion X, minor versionY).
The default name chosen by Camexporter seems to be design.X.nc, but I am able to modify that during the dialog after setting the GCode parameters. A typical name I might choose while experimenting is design.X.Y_comment.nc. That works OK and the GCode file gets saved.
But the log file always come out design.X.log. My workaround, if I want to save it, is to use the system rename capability.
Is there a more automated way to have the files names chosen_name.nc and chosen_name.log ?


No, please note that the log file is generated for debugging purposes and will eventually not be generated anymore.

2. GCode generated for Fonts: From watching the machine work, or now by running the CAM simulator, it is clear that segments that make up the font characters are not affected by the selection of "optimize paths" in the Gcode parameter setup. This results in a lot of extra machine motion when drawing for example, an "O". Rather than drawing 8 segments continuously, some segments are drawn CW, some CCW. I am guessing this is buried in the font definition tables.
I just ran an experiment - selected all text in the design file, then Modify-Explode to convert it to paths. The resulting GCode file is much larger, but viewing the simulation appears to be what I call much smoother machine motion - for example my "O"s are "move to start-draw O continuously CW-move to next letter.
Is there a better way to achieve this result?


Exploding the texts (as well as other entities if desired) is the best option. Be sure to save the drawing under a new name (e.g. mydrawing_exploded.dxf or mydrawing_tmp.dxf) after exploding entities since the original information is no longer available and texts cannot be edited anymore after exploding them. This might also make the CAM export significantly slower, though I don't see why it should make them much larger.
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Re: Using QCADCAM for Engraving Text

Postby cmcgrath5035 » Sat Apr 19, 2014 12:50 am

No, please note that the log file is generated for debugging purposes and will eventually not be generated anymore.

OK, I guess. I won't bother asking how to write into this log file from the machine configuration.

Exploding the texts (as well as other entities if desired) is the best option. Be sure to save the drawing under a new name (e.g. mydrawing_exploded.dxf or mydrawing_tmp.dxf) after exploding entities since the original information is no longer available and texts cannot be edited anymore after exploding them. This might also make the CAM export significantly slower, though I don't see why it should make them much larger.

I had a chance to run the two GCode files today.
The unexploded file ran in 18:40, the exploded in 17:20, so a little faster but not amazing.

Overall, no real difference observable in the output.

I did notice that while certain letters, for example "O", ran 'more sanely' as one continuous CCW loop, other letters, "B" and "0" [zero] gave my machine real heartburn - it just sat in one place for a while. I suspect that the "explosion" resulted in some very short curved segments that challenged the machine's accuracy.

The file size difference was 31KB vs 80KB; the Export processing time was a bit longer but not hugely so.

Summary: If I were to start the job and walk away until I heard the spindle stop, I would not be able to distinguish the difference.

Thanks for your inputs
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Re: Using QCADCAM for Engraving Text

Postby andrew » Sat Apr 19, 2014 8:54 am

Are you only using the Cyrillic_II font or also other (TrueType) fonts?

In the latter case, exploding glyphs might result in spline segments which you can explode again to obtain line segments. You might also want to have a look at explosion preferences to configure the number of spline segments per exploded spline:

Edit > Application Preferences > Modify > Explode

Lowering that number will result in small output with lower resolution.
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Re: Using QCADCAM for Engraving Text

Postby cmcgrath5035 » Sat Apr 19, 2014 3:02 pm

FYI, I just upgraded to 3.4.7, but don't expect that will change anything here.
Edit > Application Preferences > Modify > Explode
My current settings are the defaults, I believe; spline segments=64 and Ellipse segments=32.

Be sure to save the drawing under a new name (e.g. mydrawing_exploded.dxf or mydrawing_tmp.dxf) after exploding entities since the original information is no longer available and texts cannot be edited anymore after exploding them.


I did not save the file after explosion - I performed the Modify-Explode, then CamExport.
Do I need to save it first?

I was looking again at this and notice something strange, which might indicate a bug of some sort.

I find CAMImport to be very useful here.
After import, I am using the mouse to select individual characters.
I imported the file with_explode.nc (URL below ) and notice that a "B" on the bottom row has 10 segments, but a "B" on the top row has 1036 segments.
Similarly, a letter "O" on the bottom row has 9 segments, on the top row 1036 segments in the Buzz Off but 9 in Main ON
It was in fact the top row that I noticed the machine stalling.

The phrase Buzz Off, in upper left, is near the end of the GCode generation process.

One other anomaly I noticed early on, which might indicate an issue in the optimization algorithm:
The letter "H" in the lower left; the horizontal segment is the first path cut by the GCode, but the two verticals are the last(or almost last) two segments cut.

A third observation: both 3.4.6 and now 3.4.7 have now "locked up" (stopped responding to mouse clicks, etc) while working in the imported Window. I had to terminate the run when I get the "Window not responding" prompt from openSUSE.

My To-Try List:
1. Generate non-optimized GCode from the exploded file, for comparison.

Files associated with this:
Design file https://dl.dropboxusercontent.com/u/50261731/QCADCAM%20Tests/Dash%203.8%20Plate%20.dxf
no_explode.nc https://dl.dropboxusercontent.com/u/50261731/QCADCAM%20Tests/Dash%203.8.nc
with_explode.nc https://dl.dropboxusercontent.com/u/50261731/QCADCAM%20Tests/Dash%203.8_explode.nc
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Re: Using QCADCAM for Engraving Text

Postby cmcgrath5035 » Sun Apr 20, 2014 3:33 am

I hate it when that happens.
My To-Try List:
1. Generate non-optimized GCode from the exploded file, for comparison.

I tried this and found that all characters are normal, the GCode file ony a few kB larger than with un-exploded fonts.

So I tried generating with optimized code again; similar good result.

3.4.7 vs. 3.4.6 perhaps?

Went back to 3.4.6, loaded, exploded, exported optimized code, GCode file looks good as well.

I have no idea why the first attempt had the few 'bogus' character patterns.

If I find this result again, I'll try to capture the circumstances; for now, it has disappeared.
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Re: Using QCADCAM for Engraving Text

Postby cmcgrath5035 » Sun Apr 20, 2014 8:28 pm

Just to document the available info, after running the newest GCode, optimized, after explosion of fonts:

Original job - optimized code, fonts NOT exploded Run time 18:41 File Size 33kB
Next job - optimized code, fonts exploded but a few character errors Run time 17:21 File size 86kB
Final job - optimized code, fonts exploded no apparent errors Run time 15:15 File size 25kB

No perceptible difference among the end results, very different machine paths to achieve same results.

If I were producing a lot of one item, > 3 min saved on an 18:41 min job might be interesting.
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