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Messages - lasersafe

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Today I learned an interesting tidbit about the Mach 3 laser engraving plugin.  I had a 1MHz Celeron machine before and the laser plugin wouldn't work well at all.  I kept getting the "Previous Sequence not complete" crashes.  I upgraded my PC to a 3.4 GHz Athelon with 1Meg of RAM and I had the plugin working to my complete satisfaction (well almost complete as I will describe after this tidbit).  With a 3.4GHz machine I found I could turn up the Mach pulsing engine to 100Khz.  Using the plugin I could raster my x stage at 1400 in/min and get up to 1/16" burn depth in black walnut using my 40W CO2 (chinese engraver) with the power set to maximum.  This isn't too shabby considering the speed of the raster and microsecond pulses of the laser.

Ready for the interesting part?  I was playing (working) with the laser setup to finally adjust the table limits.  I crashed my Y stage into the rear wall a few too many times and crushed a wire on my X stage which shorted it to the frame.  This burned up my Allegro driver chip.  I repaired the wire and replaced the x stage motor driver with another driver I had laying around.  My original Allegro driver was set up for half step mode which gave me 500 steps per inch.  The new driver had a much finer microstepping setting that required me to set Mach 3 for 2500 steps per inch.  After the replacement I confirmed that I could indeed get my X stage to run at 1400"/min.  Surely at that point I know that the pulse train coming from Mach 3 for Xstep is screaming.  (58.333 KHz to be exact ).   I then ran the laser engraver plugin again and it wouldn't work worth a darn.  It would lose steps and give me one of those "previous sequence not complete" crash warnings.  So I guess the trajectory planner in the raster software can't keep up if the step rate is super high.  From now on, I'm going to stick with 1/2 step mode on my drivers since this gives the computer more time to think about the next step.  Perhaps high pulse rates have been affecting other users in the past and affected thier results concerning burn depth.  Since there was never an official manual for this plugin (that I know of) it could go as an unseen issue.

Now what still bugs me about the engraver plugin?  It would be cool if it could analyze the incoming image and automatically skip over the areas the do not need engraving by using a rapid Y move.  I am telling the Y to increment in 0.004" steps and it seems ridiculous for it to sit there and raster for two minutes because it hit a a 1/4" area of the image that had nothing to print.

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General Mach Discussion / GCODE VAR MONITOR and BRAINS
« on: November 20, 2009, 12:17:28 PM »
Posted days ago in the Brains category but got no response.  Can anyone out there explain the GCODE VAR MONITOR that is on the Operator pulldown?  Can this watch for a certain newly created symbol in my Gcode and read the value?  Can a BRAIN then catch that value and act upon it to fire an output on and off?  Ultimately I'm looking for a symbol that can turn a laser on and off without the latency normally associated with VB scripts or even Z axis direction bit control.

Thanks - John

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G-Code, CAD, and CAM discussions / Re: g-code newbee questions
« on: November 17, 2009, 04:22:36 PM »
You already can go from sketchup to Gcode.  First download a ruby script called skptostl and put it in your ruby scripts folder of sketchup.  Draw a small 3d object that you would like to mill, highlight it, and launch the skptostl ruby script. The script will ask if you want to export the item or the entire drawing.  Choose the item.  You will then find that you have a .stl file of your object that exactly matches the dimensions, cuts, and shape of your original 3d drawing.  STL stands for Stereo Lithography and it is a common format used in 3D printing.  Next you search the web for Freemill and download it.  You will have to register with the company that provides it, but that's just so they can call you and offer their non-free product once your hooked on CNC.  This free program will accept a .stl file and convert it to gcode for Mach 3.

Yeah, what he said.   ::)
Really, for now, I'm content with downloading freebies. Later on I'll need some special projects that may require converting CAD to G-code. Ideally I would like to convert Google sketch-up drawings to G-code with a free or extremely cheap program.
If anyone knows of something like this, would it be something you could use Carl?

Oh, and welcome to the forum from another newbie. :)

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Brains Development / Re: gcode variable that can be seen by a 'brain'?
« on: November 16, 2009, 02:18:43 PM »
Still looking for an answer.  I had one more comment to add that might spark a reply.  I notice in Mach 3 that there is a pulldown menu item called Gcode variable viewer.  I can't find anything about this function in the manual, or perhaps I'm looking at the wrong manual.  This function leads me to believe that certain variables can be grabbed from the gcode that are not necessarily motor movements or machine codes.  

I think it is clear to all that you can't turn on a laser during a pause in motion or it will burn deeper and wider than during a normal XX inch/min run.  We need the ability to run the X and Y in constant velocity mode and then turn the laser on and off without any motion delays.  It would be best if the knowledge of the pending laser on/off commands are processed by the trajectory planning section of the software so it can just happen when it sees that the trigger point has been reached in a particular motion pass.   This seems to be what is happening in the laser plugin, but the plugin has some serious problems with crashing and inability to handle rectangular images.  It also never lets us have the actual code to save.  This is an important point because when rastering across an image there might be several minutes worth of small Y movements in which the laser never fires.  It would be nice to cut out these particular sections of code and let the Y axis move quickly to the next valid position where the laser will fire during an X sweep.

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Brains Development / gcode variable that can be seen by a 'brain'?
« on: November 15, 2009, 10:45:46 PM »
I am one of the poor fools stuck trying to find a decent way to control a laser with Mach3.  The laser plugin works 'sometimes', but it crashes unexpectedly and always gives me the 'previous SEQ not completed' statement.  Perhaps I was foolish to throw away the old Chinese driver that came with my laser.  Okay, enough history.

Is there a way for me to write a variable in Gcode that will not be a machine code that pauses the motion?  I was hoping that there was some variable that could be seen by a brain and have the brain turn my laser on and off.  I have spent days playing with Mcodes and slow VB scripts with little success.  I have also tried simply changing the spindle speed parameter and tying my laser to it with a brain, but I see that Mach3 also pauses when it receives the new speed setting (even though all internal delays are set to zero).  I have also done the trick of using the direction bit for the Z axis to fire the laser.  Even with Z depths of -0.001 and super high speed settings for the fake Z motor I am still getting the jerky machine pauses when rastering the X motion.

I would like to create my gcode as before using small Z motions for laser on-off, but then I would use the find and replace feature of a text editor to change Z0.0 and Z-.001 to this new variable that will not be interpreted by a slow VB script but will instead be seen and immediately acted upon by the brain.


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G-Code, CAD, and CAM discussions / Sketchup 3D to STL to Gcode
« on: March 26, 2008, 01:51:36 PM »
I have many 3D drawing packages at my work.  AutoCad Mechanical Desktop,  Autodesk Inventor, etc., and yet the easiest package to quickly create a 3D object is the free Google Sketchup.  There is a ruby script written for sketchup that converts the file to a .STL file.  (Still free to this point)

There is a free program called freemill distributed by Mechsoft that converts the .STL to gcode that is ready for Mach3.

Indeed it all works.  I drew a quick 3D shape in Sketchup, exported as STL, converted to gcode and ran it in Mach3.

The question I have for this forum is whether there are any other free free converters of STL to gcode.  Better yet, is there anyone here on the forum that is good with ruby scripts and might be interested in writing a ruby to directly export gcode from sketchup.

-John


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