GearHeads Forum

I have been fiddling around with a 10W diode laser mounted to an old 3 axis circuit board prober.  I replaced the original electronics and kept the frame, linear rails, steppers, proximity switches and etc.  I used an old Xylotec board gathering dust in the drawer from bygone days.  Work envelope is 11"x 13". 

My first adventure in CNC was using Mach3 on a home build router with a work envelope of 30"x40" but have since migrated to Linuxcnc.  I have retrofitted metal working machines to CNC using LinuxCNC. 

So my laser setup now is working adequately for vector engraving but my goal is to do raster engraving.  I can do it but it is very slow and tends to burn for reasons that Art developed Auggie.  Sometimes Gcode isn't enough.  I have used M62/M65 to initiate the laser on/off coordinated with motion.  Not good enough.  I started down the path to induce a variable delay in the firing of the laser to accommodate for the accel/decel.  Had not finished that experiment before I was pointed towards Auggie by a friend of mine.  Setting up post processors to accommodate my particular setup is tedious so....

Before I step out and replace my current set up with Auggie and a Pokeys board, I'd like to set my performance expectations.  I suspect Auggie will drastically enhance my speed and quality to produce a photo image on wood but would like to understand what you are experiencing.  What kinds of elapsed time do you guys see for a 5"x5" photo?  What kinds of pix/in are you typically using? 

I'm very much a novice at this laser stuff so I'm sure I will have more questions for this forum that will arise especially if/when I convert to Auggie.

Thanks for the add. 
Mark

Hi Mark:

  Ive never seen LinuxCNC do a raster so I cant compare. With Mach3 I used the
engraving plugin I wrote for that purpose, but I wanted a better control of actual
power. In Auggie, it will load almost any image, and scale it to your work envelope.
  So the resolution you get will be determined by the image resolution scaled to
the work bounds. For power Auggie will vary it every ms, so if the raster is 1 second
to do 5", thats about 1000 different power levels from the pwm. If set to 5 seconds
across by whatever feedrate you select, thats 5000 individual power settings from
0 - 100% as set by pixel density. Auggie loads and processes the images and so
allows for flipping the image density and such.

  As for time, thats really depending on too many factors. My 10watt co2 may take
30 minutes to do a 5x7 at high res, where my galvo could do it in 4 at 50 watts.

  Its a jump to get it all hooked up I know, so ask anything you think may be pertinent
and Ill let you know how mine works. I have 2 lasers on Auggie currently, and no
cnc systems. My CNC is still driven by a custom version of Mach3 that I no longer
recall what I changed in, as I too believe if it works well, let it.

  One note for photo's, the problem I ran into was that while Auggie will send
power commands from 1-100% in steps of 1, if you need to reduce power by
its power override command to say 50%, then the power thats sent is
0 - 50 in steps of 1. So lowering power reduces resolution. There is an
arduino project I put on the board that can take the 0-100PWM and convert it
to 100 levels from 0 - desired max. This PWM converter helps if that problem
makes it hard to find just the right power for the material. If your laser
already has a max power setting you may not need it.



Art

Art,  good info.  Now let me play it back to see if I really understand.

My "system" (imaging app and postprocessor app) now codes a 0.008" move at max vel (246ipm) and power level.  Then it moves another 0.008" at max vel but at essentially 0 power (.1%).  Repeat until done. So the effective velocity is and nowhere near 200ipm. I've never measured/calculated the effective velocity given the processing delays, accell and decell.  I can tell you that I recently engraved a 5x5 and it took well over 4 hours so 30 minutes sounds like heaven.  Pretty tough to get a handle on all of the raster engraving variables (image edits, resolution, dither vs. grayscale et al) when it takes 4 hours to see the results.

I think you are saying that the time to engrave using Auggie would be more related to my laser power available than machine velocity.  Is that because the script file handles the power changes as a coordinated move with the axis(s) in motion (linear, spiral whatever)? So my motion would be at (closer to) the true programmed velocity.  Right now I'm limited by the effective velocity of the extremely short moves and the related accel/decell.  I haven't even seen the 10W diode as the limiting factor.  In fact, in baltic birch I am running at about 20% power to prevent burning at my effective feed rate.  With Auggie at my max velocity it would take 1.2s to traverse 5".  If the 10W is enough power for effective burning at 246ipm then it should take about 14 mins to engrave the image.

My laser power level is PWM controlled. Right now I have the frequency set at 100Hz and a power range selectable between 0 and 1200.  Probably too much and unnecessary power range but that's easily changed in my HAL file.  I just haven't experimented with that yet.  And yes, I can set the max power to be used in the image/postprocesser to whatever I think appropriate for the material used. 

To migrate to Auggie, I think I would have to get the Pokeys57cnc board and 3 stepper drives since the xylotec breakout has the drives integrated.  From what I have read I think that is about all. 

Then I ask myself, why not change my Mach3 router (smoothstepper and C11 board) out with the Pokeys board and put the Laser right on the machine with a larger work envelope and a 4th axis.  Mach3 (still) for the router.  Auggie for the laser.  Same computer.  Same physical platform. 

Then I think about using the extra rails, ball screws and materials I have hanging around and just make a dedicated larger laser pedal my current "little laser learning" platform. 

My head hurts.  I have decisions to make.  Wish me luck.


Mark

Mark:

>>I think you are saying that the time to engrave using Auggie would be more related to my laser power available than machine velocity.  Is that because the script file handles the power changes as a coordinat ed move with the axis(s) in motion (linear, spiral whatever)?

  Yes, in fact once the image augment file is loaded , whenever the tool moves at feedrate in the image envelope size as set when creating the augment, the laser fires at the pixel in that positions power. In other words once the image is loaded, you can do any gcode to engrave it, even a spiral or spirograph, the image position will burn appropriately. You dont see any drop in speed and can raster at speeds as high as you can go. I raster on my galvo laser at almost 1000 ipm with the laser doing fine, but the resolution drops as the speeds get too high as 1ms of time can be quite a distance..and all motions are 1ms long internally.

>> So my motion would be at (closer to) the true programme d velocity.  Right now I'm limited by the effective velocity of the extremely short moves and the related accel/decell.  I haven't even seen the 10W diode as the limiting factor.  In fact, in baltic birch I am running at about 20% power to prevent burning at my effective feed rate.  With Auggie at my max velocity it would take 1.2s to traverse 5".  If the 10W is enough power for effective burning at 246ipm then it should take about 14 mins to engrave the image.

  Sounds about right.

>>>My laser power level is PWM controlle d. Right now I have the frequency set at 100Hz and a power range selectabl e between 0 and 1200.  Probably too much and unnecessa ry power range but that's easily changed in my HAL file.  I just haven't experimen ted with that yet.  And yes, I can set the max power to be used in the image/postprocesser to whatever I think appropria te for the material used. 

  Pokeys puts out a pwm that you can set the base frequency of. So in Auggie I currently use 20Khz PWM. This is a settable value though and any pwm is in theory possible.

>>To migrate to Auggie, I think I would have to get the Pokeys57c nc board and 3 stepper drives since the xylotec breakout has the drives integrate d.  From what I have read I think that is about all. 

  Yes, Auggie will only use a Pokeys, and I recommend the 57cnc, though a 56 can be used with the external motion board. Any pokeys can be used for motion, but only the 57cnc or external motor controller
option for the 56 has laser power on the fly capability. It was added specifically for Auggie.

>>>Then I ask myself, why not change my Mach3 router (smoothste pper and C11 board) out with the Pokeys board and put the Laser right on the machine with a larger work envelope and a 4th axis.  Mach3 (still) for the router.  Auggie for the laser.  Same computer.  Same physical platform. 

  It can be a hassle swapping between m3 and auggie. M3 tends to keep all the settings locally while auggie
tends to simply keep them in the pokeys. There is a save/load config, but it got a bit futzy after a
pokeys firmware update and I havent yet fixed it as I only use Auggie on my laser.

>>>My head hurts.  I have decisions to make.  Wish me luck.

  , good luck, its always the way, one project leads to another...

Art