Re: [Emc-users] LinuxCNC as laser cutter?

[Danny Miller]

I've been inside Universal Laser Systems lasers.  The laser doesn't have 
a throttle, just an on/off for the beam, and it's like this:

The beam is about 0.008" dia, 1/125th of an inch.

If you specify <100% power in vector mode, there is a Pulse Per Inch 
(PPI) factor used.  If you specify 50% power 300 PPI, it cuts at 1/600th 
in on, 1/600th in off. When it's on it's full power. That's not wide 
enough of a stop to leave any unburned length. For any given point, it 
receives less exposure to the beam.

When hitting the corners of a square, of course, acceleration rules 
apply to full stop/full start the vectors, and since it's less than the 
commanded speed, the exposure would be increased past the specification. 
So it does add a  DIFFERENT pwm to reduce power when the speed is below 
the target command, but it's fast- like 1000 pulses per inch, or might 
be in the time domain, I don't know.  It's not affected by the commanded 
PPI.  This does seem to mean that if you command 50% power and 500PPI, 
when it does the start/end of vectors and isn't at commanded speed, 
there's a series of 1/600th in on/off segments, AND within the ON 
segment it's pulsing at 1000PPI.

With rastering, there's two modes.  One is more "analog" and does high 
frequency PWM based on shade as it passes.
The other uses a fixed-length PWM as it goes, based on shade. Like on 
333 vertical raster lines per inch, it has a 60-lines-per-inch 
horizontal resolution.  That is, a 127 value in an 8-bit greyscale is 
1/120th in on, 1/120th in off.  It's an offset pattern, every other line 
starts 1/120th of an inch offset, to make a diamond-shaped grid.

There's also random-density mode, where it makes dots.  But it's hard to 
really nail down what it's doing- the laser must burn in a line.  It 
can't actually do a circular dot without stopping, which it doesn't do.  
It can burn pill-shapes of varying lengths.

Just thinking on this- you COULD specify that a straight 50% power 
vector line is a long string of G-codes- M62, one  G11/600th in segment 
on, M63, one G1 1/1600th off, interleaved over and over. It would be a 
VERY long file, and might have slow execution, and won't take into 
account acceleration.  Also, it is not uncommon to want to change power 
on the fly, and that'd be impossible- you'd have to regenerate the whole 
G-code.

FYI, in my experience with ULS lasers, yes you can change the speed & 
power of VECTORS on the machine after the job is generated.  However you 
cannot change the number of vertical lines per inch on rastering.  You 
can change the raster speed.  Which makes sense.

So the way I interpret it, no, that's all totally wrong to generate 
G-code pulses within the vectors, instead you'd generate the PWM within 
LinuxCNC's software.

But, now, rastering- that's genuinely complicated.  Like I say, at least 
2 modes here.  In either case I can't imagine how to do it with 
LinuxCNC's software.  In the case of the "analog raster mode" (using a 
high speed PWM and changing it rapidly), well I still don't get how 
you'd specify all the raster data.  You could use the Z to specify the 
power, but then it'll want to ramp into and out of pixels, which sounds 
pretty wrong.  e.g. with 100 DPI 50% gray, it would be:
G1 X0  Y0 Z0
G1 X0.05 Y0 Z1
G1 X0.10 Y0 Z0

And you'd end up with a sawtoothed path, instead of a square pixel.  
That's not quite right.  It would have to be:
G1 X0 Y0 Z0
G0 Z1
G1 X0.05 Y0
G0 Z0
G1 X0.10 Y0

Which might work, but it sure sounds awkward.

Danny


On 4/30/2016 7:22 AM, Nicklas Karlsson wrote:
> If you have problem with PWM signal generation there are plenty of cheap
> micro controller development board available although protocols may be
> worse. I guess it could be an idea to search m-codes for "professional"
> laser cutters or maybe reuse codes usually used for spindle.
>
> 2016-04-30 3:48 GMT+02:00 Bruce Layne :
>
>> I still haven't built my 3' X 5' 80W CNC laser, but it'll be controlled
>> by LinuxCNC when I do.  I've had a big pile of laser parts for almost
>> three years.  Maybe later this summer, if I finally find some mojo.
>>
>> LinuxCNC is better for cutting and embossing/engraving lines. LinuxCNC
>> is not good for raster laser engraving.  Most of my laser jobs are
>> cutting and light scoring which are essentially vector jobs, but I do
>> have a few logos that are currently raster engraved on a friend's laser,
>> which is essentially operating as a Windows printer using a proprietary
>> printer driver, under CorelDraw.  My logos are simple, made of solid
>> shapes, and I expect to render them as vector engravings by outputting
>> vector image files from Inkscape.  That's the plan, anyway.  If you want
>> to laser engrave photographs, you will probably need some way to raster
>> engrave.  In that case, LinuxCNC may not be a good option for you.
>>
>> I've seen a few CNC lasers that used the -Z hack to turn the laser on,
>> and that does have a certain simplicity, but I think it's

Re: [Emc-users] LinuxCNC as laser cutter?

[samco]

Long thread but Ben created a Hal component to do rastering with the printer 
port. 

http://www.buildlog.net/forum/viewtopic.php?f=16&t=557

Sam

On Sat, 30 Apr 2016 13:39:57 +0100
 Sarah Armstrong  wrote:
> Linuxcnc works fine for Laser cutting ,
> 
> Laser rasterising is a totally different matter , and needs to be looked at
> from a different perspective
> it also depends on how your laserbeam is switched , and the modulation type
> used .
> their is some limited information regarding rasterising on the Wiki Pages .
> 
> 
> 
> On 30 April 2016 at 13:22, Nicklas Karlsson 
> wrote:
> 
> > If you have problem with PWM signal generation there are plenty of cheap
> > micro controller development board available although protocols may be
> > worse. I guess it could be an idea to search m-codes for "professional"
> > laser cutters or maybe reuse codes usually used for spindle.
> >
> > 2016-04-30 3:48 GMT+02:00 Bruce Layne :
> >
> > > I still haven't built my 3' X 5' 80W CNC laser, but it'll be controlled
> > > by LinuxCNC when I do.  I've had a big pile of laser parts for almost
> > > three years.  Maybe later this summer, if I finally find some mojo.
> > >
> > > LinuxCNC is better for cutting and embossing/engraving lines. LinuxCNC
> > > is not good for raster laser engraving.  Most of my laser jobs are
> > > cutting and light scoring which are essentially vector jobs, but I do
> > > have a few logos that are currently raster engraved on a friend's laser,
> > > which is essentially operating as a Windows printer using a proprietary
> > > printer driver, under CorelDraw.  My logos are simple, made of solid
> > > shapes, and I expect to render them as vector engravings by outputting
> > > vector image files from Inkscape.  That's the plan, anyway.  If you want
> > > to laser engrave photographs, you will probably need some way to raster
> > > engrave.  In that case, LinuxCNC may not be a good option for you.
> > >
> > > I've seen a few CNC lasers that used the -Z hack to turn the laser on,
> > > and that does have a certain simplicity, but I think it's too kludgey
> > > with too many tradeoffs and undesirable behaviors from the trajectory
> > > planner.  I plan on using M codes to turn the laser on and off.  I also
> > > plan on using the Z axis to drive stepper motors to jog the table
> > > elevation when setting up a job at the correct height.  In theory, I
> > > could laser engrave 3D objects by using the Z axis as well, but I don't
> > > plan on using any Z motion in my laser G code, other than maybe a fixed
> > > Z offset at the beginning from the homed Z position is I decide to have
> > > a hardware Z=0 with relative offsets from that for each job.  I also
> > > plan on a light duty 4th axis for laser cutting round objects.  One of
> > > my production jobs requires laser cutting and embossing cylindrical
> > tubes.
> > >
> > > For reduced power settings, I'll pulse width modulate a signal to turn
> > > the laser on and off fairly quickly.
> > >
> > > Many people would assume that it'd be easier and faster to draw
> > > something in CorelDraw and "print" it on the laser, but I hate it, and
> > > would much rather have direct control of the G code.  The CorelDraw
> > > print driver for the laser may be faster when making one or two of
> > > something, but it gives me no control over the order in which features
> > > are cut on the laser, which results in clumsy production jobs that are
> > > difficult to run because the order of subsequent steps are random, and
> > > there is a lot of wasted motion.  I want the control that I get writing
> > > G code by hand, in a logical progression.  To some extent, this is an
> > > extension of the lack of control I have in Windows, compared to Linux.
> > > I think it's more of a philosophical difference than a technical
> > > difference.
> > >
> > > Sorry, but I haven't implemented any of this LinuxCNC laser stuff yet,
> > > so I have only this generic advice and no specific LinuxCNC example code.
> > >
> > >
> > >
> > > On 04/29/2016 08:29 PM, Danny Miller wrote:
> > > > Having some preliminary thoughts about LinuxCNC's appropriateness to be
> > > > a laser cutter, like 120W CO2.  The other option is the open-source
> > > > Lasersaur or Axecut.   Those aren't particularly advanced trajectory
> > > > planners or anything.
> > > >
> > > >Can it be a good tool for lasering?
> > > >
> > > > I did see where some people had done it with some hacks, but I don't
> > > > know how practical they are.  There was something about using a
> > negative
> > > > Z-value to turn on the laser.
> > > >
> > > > A lot of things come to mind.
> > > >
> > > > One, often the laser needs to turn on and off quickly, without
> > > > stopping.  If it's technically implemented as a Z-move, it would slow
> > to
> > > > move the nonexistent Z-axis.  Would that work by just changing the
> > > > Z-acceleration to something ridiculously high?
> > > >
> > > > Two, sometimes we do reduce the cut powe

Re: [Emc-users] LinuxCNC as laser cutter?

[Sarah Armstrong]

Linuxcnc works fine for Laser cutting ,

Laser rasterising is a totally different matter , and needs to be looked at
from a different perspective
it also depends on how your laserbeam is switched , and the modulation type
used .
their is some limited information regarding rasterising on the Wiki Pages .



On 30 April 2016 at 13:22, Nicklas Karlsson 
wrote:

> If you have problem with PWM signal generation there are plenty of cheap
> micro controller development board available although protocols may be
> worse. I guess it could be an idea to search m-codes for "professional"
> laser cutters or maybe reuse codes usually used for spindle.
>
> 2016-04-30 3:48 GMT+02:00 Bruce Layne :
>
> > I still haven't built my 3' X 5' 80W CNC laser, but it'll be controlled
> > by LinuxCNC when I do.  I've had a big pile of laser parts for almost
> > three years.  Maybe later this summer, if I finally find some mojo.
> >
> > LinuxCNC is better for cutting and embossing/engraving lines. LinuxCNC
> > is not good for raster laser engraving.  Most of my laser jobs are
> > cutting and light scoring which are essentially vector jobs, but I do
> > have a few logos that are currently raster engraved on a friend's laser,
> > which is essentially operating as a Windows printer using a proprietary
> > printer driver, under CorelDraw.  My logos are simple, made of solid
> > shapes, and I expect to render them as vector engravings by outputting
> > vector image files from Inkscape.  That's the plan, anyway.  If you want
> > to laser engrave photographs, you will probably need some way to raster
> > engrave.  In that case, LinuxCNC may not be a good option for you.
> >
> > I've seen a few CNC lasers that used the -Z hack to turn the laser on,
> > and that does have a certain simplicity, but I think it's too kludgey
> > with too many tradeoffs and undesirable behaviors from the trajectory
> > planner.  I plan on using M codes to turn the laser on and off.  I also
> > plan on using the Z axis to drive stepper motors to jog the table
> > elevation when setting up a job at the correct height.  In theory, I
> > could laser engrave 3D objects by using the Z axis as well, but I don't
> > plan on using any Z motion in my laser G code, other than maybe a fixed
> > Z offset at the beginning from the homed Z position is I decide to have
> > a hardware Z=0 with relative offsets from that for each job.  I also
> > plan on a light duty 4th axis for laser cutting round objects.  One of
> > my production jobs requires laser cutting and embossing cylindrical
> tubes.
> >
> > For reduced power settings, I'll pulse width modulate a signal to turn
> > the laser on and off fairly quickly.
> >
> > Many people would assume that it'd be easier and faster to draw
> > something in CorelDraw and "print" it on the laser, but I hate it, and
> > would much rather have direct control of the G code.  The CorelDraw
> > print driver for the laser may be faster when making one or two of
> > something, but it gives me no control over the order in which features
> > are cut on the laser, which results in clumsy production jobs that are
> > difficult to run because the order of subsequent steps are random, and
> > there is a lot of wasted motion.  I want the control that I get writing
> > G code by hand, in a logical progression.  To some extent, this is an
> > extension of the lack of control I have in Windows, compared to Linux.
> > I think it's more of a philosophical difference than a technical
> > difference.
> >
> > Sorry, but I haven't implemented any of this LinuxCNC laser stuff yet,
> > so I have only this generic advice and no specific LinuxCNC example code.
> >
> >
> >
> > On 04/29/2016 08:29 PM, Danny Miller wrote:
> > > Having some preliminary thoughts about LinuxCNC's appropriateness to be
> > > a laser cutter, like 120W CO2.  The other option is the open-source
> > > Lasersaur or Axecut.   Those aren't particularly advanced trajectory
> > > planners or anything.
> > >
> > >Can it be a good tool for lasering?
> > >
> > > I did see where some people had done it with some hacks, but I don't
> > > know how practical they are.  There was something about using a
> negative
> > > Z-value to turn on the laser.
> > >
> > > A lot of things come to mind.
> > >
> > > One, often the laser needs to turn on and off quickly, without
> > > stopping.  If it's technically implemented as a Z-move, it would slow
> to
> > > move the nonexistent Z-axis.  Would that work by just changing the
> > > Z-acceleration to something ridiculously high?
> > >
> > > Two, sometimes we do reduce the cut power, to only mark the surface
> > > instead of cutting it.  Initially you reduce the depth of cut by
> > > increasing speed, but if it's paper, you can't increase the speed
> > > enough, you have to cut back on the power.  And the required power will
> > > change inside the document.  How would that get specified, just with a
> > > differing Z-depth?
> > >
> > > When not at the specified sp

Re: [Emc-users] LinuxCNC as laser cutter?

[Nicklas Karlsson]

If you have problem with PWM signal generation there are plenty of cheap
micro controller development board available although protocols may be
worse. I guess it could be an idea to search m-codes for "professional"
laser cutters or maybe reuse codes usually used for spindle.

2016-04-30 3:48 GMT+02:00 Bruce Layne :

> I still haven't built my 3' X 5' 80W CNC laser, but it'll be controlled
> by LinuxCNC when I do.  I've had a big pile of laser parts for almost
> three years.  Maybe later this summer, if I finally find some mojo.
>
> LinuxCNC is better for cutting and embossing/engraving lines. LinuxCNC
> is not good for raster laser engraving.  Most of my laser jobs are
> cutting and light scoring which are essentially vector jobs, but I do
> have a few logos that are currently raster engraved on a friend's laser,
> which is essentially operating as a Windows printer using a proprietary
> printer driver, under CorelDraw.  My logos are simple, made of solid
> shapes, and I expect to render them as vector engravings by outputting
> vector image files from Inkscape.  That's the plan, anyway.  If you want
> to laser engrave photographs, you will probably need some way to raster
> engrave.  In that case, LinuxCNC may not be a good option for you.
>
> I've seen a few CNC lasers that used the -Z hack to turn the laser on,
> and that does have a certain simplicity, but I think it's too kludgey
> with too many tradeoffs and undesirable behaviors from the trajectory
> planner.  I plan on using M codes to turn the laser on and off.  I also
> plan on using the Z axis to drive stepper motors to jog the table
> elevation when setting up a job at the correct height.  In theory, I
> could laser engrave 3D objects by using the Z axis as well, but I don't
> plan on using any Z motion in my laser G code, other than maybe a fixed
> Z offset at the beginning from the homed Z position is I decide to have
> a hardware Z=0 with relative offsets from that for each job.  I also
> plan on a light duty 4th axis for laser cutting round objects.  One of
> my production jobs requires laser cutting and embossing cylindrical tubes.
>
> For reduced power settings, I'll pulse width modulate a signal to turn
> the laser on and off fairly quickly.
>
> Many people would assume that it'd be easier and faster to draw
> something in CorelDraw and "print" it on the laser, but I hate it, and
> would much rather have direct control of the G code.  The CorelDraw
> print driver for the laser may be faster when making one or two of
> something, but it gives me no control over the order in which features
> are cut on the laser, which results in clumsy production jobs that are
> difficult to run because the order of subsequent steps are random, and
> there is a lot of wasted motion.  I want the control that I get writing
> G code by hand, in a logical progression.  To some extent, this is an
> extension of the lack of control I have in Windows, compared to Linux.
> I think it's more of a philosophical difference than a technical
> difference.
>
> Sorry, but I haven't implemented any of this LinuxCNC laser stuff yet,
> so I have only this generic advice and no specific LinuxCNC example code.
>
>
>
> On 04/29/2016 08:29 PM, Danny Miller wrote:
> > Having some preliminary thoughts about LinuxCNC's appropriateness to be
> > a laser cutter, like 120W CO2.  The other option is the open-source
> > Lasersaur or Axecut.   Those aren't particularly advanced trajectory
> > planners or anything.
> >
> >Can it be a good tool for lasering?
> >
> > I did see where some people had done it with some hacks, but I don't
> > know how practical they are.  There was something about using a negative
> > Z-value to turn on the laser.
> >
> > A lot of things come to mind.
> >
> > One, often the laser needs to turn on and off quickly, without
> > stopping.  If it's technically implemented as a Z-move, it would slow to
> > move the nonexistent Z-axis.  Would that work by just changing the
> > Z-acceleration to something ridiculously high?
> >
> > Two, sometimes we do reduce the cut power, to only mark the surface
> > instead of cutting it.  Initially you reduce the depth of cut by
> > increasing speed, but if it's paper, you can't increase the speed
> > enough, you have to cut back on the power.  And the required power will
> > change inside the document.  How would that get specified, just with a
> > differing Z-depth?
> >
> > When not at the specified speed due to acceleration limits, the software
> > needs to reduce the power to avoid delivering more energy/mm than the
> > user specified.  Actually this sounds like the easiest part, presuming
> > we can get an accurate instantaneous speed.
> >
> > All power adjustments come via a PWM pin.
> >
> > Danny
> >
>
>
>
> --
> Find and fix application performance issues faster with Applications
> Manager
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Re: [Emc-users] LinuxCNC as laser cutter?

[Gene Heskett]

On Saturday 30 April 2016 05:56:10 andy pugh wrote:

> On 30 April 2016 at 05:16, Danny Miller  wrote:
> > http://www.machsupport.com/forum/index.php?topic=27782.15;wap2
> >
> > Looks like they're saying M62 actuall takes effect slightly before
> > the G-code command executes, which could be a problem.
>
> That's Mach :-)
>
> LinuxCNC turns on the output and starts the associated move at the
> same time.
>
> However, for rastering you really want to be moving at constant speed
> and "clock out" the image data depending on position.

This might be doable with halstreamer and streamer, and might be used 
with a base-thread clocking rate.  The man pages do not indicate there 
would be a line length limit other than the size of the shared memory.

Would that offer fine enough detail, switching the laser on and off in 
base-thread time slices?

I can see that since the data would best be described as random, that it 
would need to be fetched in bit counts that would represent one full 
line scan per line since there would not be a unique EOL character to 
such data.

The laser would need to be turned off by the fifo empty, motion paused or 
moved to the next line while the fifo is being reloaded from the file as 
that would take an arbitrary amount of time.  Details of the startup 
acceleration I see as a positioning problem because you would want the 
laser carrier moving at full speed and at the true starting position of 
the image when the first bit was clocked out.  The inclusion of the 
enable bit mentioned in the man page for streamer would make some of the 
other timing requirements much easier to meet.

To work in both directions would be desirable as a retrace move would be 
a huge time waster, but inverting the order of the fifo clockout as 
opposed to pre-ordering as the data file was being generated seems like 
the better idea.  I can sure see a lot of cpu being used during the fifo 
reloading time at the end of each scanned line to accomplish this.  If 
clockout from whichever end of the fifo is needed, it seems the 
direction bit of the axis doing the scanning might be usable for that.

Details TBD of course. Size of the scanned image and its scaling to fit 
the image being cut would have to be preprocessor problems as any change 
in the size and scaling would require the source file to be regenerated.
I could also see the potential for 3D by clocking out a byte at a time 
which controlled the lasers power for that base-thread slice of time.  
The files size would of course be 8x the size of an on-off bitfile.  
That might, from available memory limits, constrain the size of the 
image being constructed as I can't imagine a mid line reload without 
artifacts in the image.

Food for the concept at least, I'll get me coat. :)

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] LinuxCNC as laser cutter?

[andy pugh]

On 30 April 2016 at 05:16, Danny Miller  wrote:
> http://www.machsupport.com/forum/index.php?topic=27782.15;wap2
>
> Looks like they're saying M62 actuall takes effect slightly before the
> G-code command executes, which could be a problem.

That's Mach :-)

LinuxCNC turns on the output and starts the associated move at the same time.

However, for rastering you really want to be moving at constant speed
and "clock out" the image data depending on position.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] LinuxCNC as laser cutter?

[Gene Heskett]

On Friday 29 April 2016 23:07:00 Todd Zuercher wrote:

>  More proof, you get what you pay for employee wise.

I think the operative phrase is TANSTAAFL, Todd.  I have worked for 
people who did not understand that, for short periods of time.

I have worked for those that did understand it well for much longer 
periods of time, like 18 years at my last position.  For those that did 
understand it, I never had to ask for a raise, I just got them, and 
generally well above a COLA raise.  When I retired 2002/06/30 the 
average CE's salary in the market 160-170 bracket was about $38k 
according to surveys the trade rags published about annually.  Yet the 
last IRS year I worked, I had to admit to about $57k.  About a year 
before that, I knew KTLA was looking again, but they were offering about 
$65k, and that would have been about $200k short of what it would have 
taken to make me even want to be in the same state as LA. I'd already 
seen too much of kalipornias crazy legal system in the times I succumbed 
to the lure.  I asked around as discreetly as I could when the next NAB 
came around, and the opinions of KTLA from the real engineers were 
pretty uniformly poor.

Funny thing, we had bought the video production switcher from the Penny's 
production house in NYC about 16 years before, and that thing was a 
nightmare because of its complexity AND the fact that it had lived in 
NYC's poor air, causing a lot of corrosion.  But I kept it going until 
several years later I was offered essentially the same switcher out of 
the KTLA studios.  Cali had the better air so it was in much better 
shape in terms of pollution caused damages.  So we made the swap, and 
only once it had been integrated into our system, did I realize that 
apparently none of the circuit failures it had ever had, they didn't 
have anyone who was sharp enough to fix it. Took me about 6 months to 
find most of it, at one point writing code in Basic09 running on a 
TRS-80 color computer, to reach in and exercise every signal path in its 
control circuitry. So the day we retired it as I was retiring, it was 
working better than it did the day we dropped it into the console cutout 
12 years or so prior.  But we did get all the goody out of it I think.

That same color computer and a couple floppy drives, was also a 4x faster 
that the Grass Valley Groups EDisk that the technical directors used so 
that each one had his own "bag of tricks" personality he could load into 
the switcher 1 minute before a live newscast started, so that all the 
effects he was used to using were always on the same button when he 
pushed it.  I had about $250 in that, but GVG would have sold me their 
version that was 4x slower, and had 2 digit number filenames, so the 
limit was 99, while my version used up to 29 character English 
filenames.

But Grass wanted $20k for their version.  Never could figure that one 
out.  OTOH, I have serious doubts that Grass ever made the 50th one of 
those switchers as it was about $275k brand new in the late 70's or 
early '80's. It was at the time, plainly targetted at the top 10 market 
stations or production houses like Penny's or General Mills.  Facilities 
with millions a month for cash flow.

But it was fun while it lasted.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] LinuxCNC as laser cutter?

[Danny Miller]

Rastering performance is an absolute requirement.

Also, I've run into problems with machines (Universal Laser Systems, 
older ones at least) trying to do a whole lot of complicated vectors, or 
even just a circle.  Or,  a dotted line made it lose its mind.   Poor 
trajectory planning on some cases.

In fact, the machine lost it badly on dotted lines.  From the look of 
it, if a vector's not connected to another vector, it has to do a full 
stop at the start and end of that vector.  Which, no, really doesn't 
make sense.

"lucid"?

Danny

On 4/29/2016 9:08 PM, Ricardo Moscoloni wrote:
> i would say yes!, i have an 80w laser with ubuntu8.04 and ben´s
> laserfreq.comp and some magic halstreamer implementation by ben that do
> rastering with lcnc that work very very!! well.
> my testing with m62 still produces some deaccel in my particular machine,
> but dont do further testing due to lack of time in this production machine.
> is old hardy, i wasnt able to mount lucid due to the machines old pc mb, to
> test new tp but i encourage you to take the tour!.
> http://www.buildlog.net/forum/viewtopic.php?f=16&t=557
> to anyone reading this with some programming skills i will glad to see it
> bundle that into lcnc
> regards
> rck
>
>
> 2016-04-29 22:48 GMT-03:00 Bruce Layne :
>
>> I still haven't built my 3' X 5' 80W CNC laser, but it'll be controlled
>> by LinuxCNC when I do.  I've had a big pile of laser parts for almost
>> three years.  Maybe later this summer, if I finally find some mojo.
>>
>> LinuxCNC is better for cutting and embossing/engraving lines. LinuxCNC
>> is not good for raster laser engraving.  Most of my laser jobs are
>> cutting and light scoring which are essentially vector jobs, but I do
>> have a few logos that are currently raster engraved on a friend's laser,
>> which is essentially operating as a Windows printer using a proprietary
>> printer driver, under CorelDraw.  My logos are simple, made of solid
>> shapes, and I expect to render them as vector engravings by outputting
>> vector image files from Inkscape.  That's the plan, anyway.  If you want
>> to laser engrave photographs, you will probably need some way to raster
>> engrave.  In that case, LinuxCNC may not be a good option for you.
>>
>> I've seen a few CNC lasers that used the -Z hack to turn the laser on,
>> and that does have a certain simplicity, but I think it's too kludgey
>> with too many tradeoffs and undesirable behaviors from the trajectory
>> planner.  I plan on using M codes to turn the laser on and off.  I also
>> plan on using the Z axis to drive stepper motors to jog the table
>> elevation when setting up a job at the correct height.  In theory, I
>> could laser engrave 3D objects by using the Z axis as well, but I don't
>> plan on using any Z motion in my laser G code, other than maybe a fixed
>> Z offset at the beginning from the homed Z position is I decide to have
>> a hardware Z=0 with relative offsets from that for each job.  I also
>> plan on a light duty 4th axis for laser cutting round objects.  One of
>> my production jobs requires laser cutting and embossing cylindrical tubes.
>>
>> For reduced power settings, I'll pulse width modulate a signal to turn
>> the laser on and off fairly quickly.
>>
>> Many people would assume that it'd be easier and faster to draw
>> something in CorelDraw and "print" it on the laser, but I hate it, and
>> would much rather have direct control of the G code.  The CorelDraw
>> print driver for the laser may be faster when making one or two of
>> something, but it gives me no control over the order in which features
>> are cut on the laser, which results in clumsy production jobs that are
>> difficult to run because the order of subsequent steps are random, and
>> there is a lot of wasted motion.  I want the control that I get writing
>> G code by hand, in a logical progression.  To some extent, this is an
>> extension of the lack of control I have in Windows, compared to Linux.
>> I think it's more of a philosophical difference than a technical
>> difference.
>>
>> Sorry, but I haven't implemented any of this LinuxCNC laser stuff yet,
>> so I have only this generic advice and no specific LinuxCNC example code.
>>
>>
>>
>> On 04/29/2016 08:29 PM, Danny Miller wrote:
>>> Having some preliminary thoughts about LinuxCNC's appropriateness to be
>>> a laser cutter, like 120W CO2.  The other option is the open-source
>>> Lasersaur or Axecut.   Those aren't particularly advanced trajectory
>>> planners or anything.
>>>
>>> Can it be a good tool for lasering?
>>>
>>> I did see where some people had done it with some hacks, but I don't
>>> know how practical they are.  There was something about using a negative
>>> Z-value to turn on the laser.
>>>
>>> A lot of things come to mind.
>>>
>>> One, often the laser needs to turn on and off quickly, without
>>> stopping.  If it's technically implemented as a Z-move, it would slow to
>>> move the nonexistent Z-axis.  Would that work by just

Re: [Emc-users] LinuxCNC as laser cutter?

[Danny Miller]

Hmm.

http://www.machsupport.com/forum/index.php?topic=27782.15;wap2

Looks like they're saying M62 actuall takes effect slightly before the 
G-code command executes, which could be a problem.

How would you tie in requested power and modulate the power according to 
the instantaneous linear speed the trajectory planner ends up with?

What's wrong with tying it so z=1 is 100% power, give a ridiculously 
high acceleration on the Z so it's not slowing down the motion, and 
somehow make a PWM output with a duty cycle of z*(actual 
velocity)/(feedrate)?

e.g.  the g-code is:
starting from X8, Y0
G0 X10 Y0
G0 Z1
G1 X20 F20
G0 Z0

At X=0.1, the velocity is still ramping up and has a value of 10. The 
PWM should be at 50% for half power at that point, so it'll deliver the 
same energy per inch across the entire cut.

Well... hmm, path smoothing might make it "curve" into Z=1 instead of 
just turning on there.  There would be no need for smoothing here.

I'm worried how bad rastering would get if it were represented in 
G-code.  Then again, I do pull in huge raster jobs with 1/16" bits 
anyhow on the CNC.

Danny

On 4/29/2016 7:55 PM, andy pugh wrote:
> On 30 April 2016 at 01:29, Danny Miller  wrote:
>> There was something about using a negative
>> Z-value to turn on the laser.
> M62 works better and does not break blending.
>


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Re: [Emc-users] LinuxCNC as laser cutter?

[Todd Zuercher]

A number of years ago I used to run the lasers where I work.  We printed to 
them using Corel Draw (I don't remember the version number.)  But back then I 
was able to select different sections of the graphic to be rastered, make it a 
different color, and then set the order that each color was printed.  By doing 
that I was able to reduce lasering time by almost half on some files.  Not long 
after I left the laser room, they updated to a newer version that broke the way 
we were controlling the order.  I don't think the people who replaced me were 
ever able to figure it out. They aren't the brightest, or most computer 
literate group in there.  More proof, you get what you pay for employee wise.

- Original Message -
From: "Bruce Layne" 
To: "Enhanced Machine Controller (EMC)" 
Sent: Friday, April 29, 2016 9:48:33 PM
Subject: Re: [Emc-users] LinuxCNC as laser cutter?

I still haven't built my 3' X 5' 80W CNC laser, but it'll be controlled 
by LinuxCNC when I do.  I've had a big pile of laser parts for almost 
three years.  Maybe later this summer, if I finally find some mojo.

LinuxCNC is better for cutting and embossing/engraving lines. LinuxCNC 
is not good for raster laser engraving.  Most of my laser jobs are 
cutting and light scoring which are essentially vector jobs, but I do 
have a few logos that are currently raster engraved on a friend's laser, 
which is essentially operating as a Windows printer using a proprietary 
printer driver, under CorelDraw.  My logos are simple, made of solid 
shapes, and I expect to render them as vector engravings by outputting 
vector image files from Inkscape.  That's the plan, anyway.  If you want 
to laser engrave photographs, you will probably need some way to raster 
engrave.  In that case, LinuxCNC may not be a good option for you.

I've seen a few CNC lasers that used the -Z hack to turn the laser on, 
and that does have a certain simplicity, but I think it's too kludgey 
with too many tradeoffs and undesirable behaviors from the trajectory 
planner.  I plan on using M codes to turn the laser on and off.  I also 
plan on using the Z axis to drive stepper motors to jog the table 
elevation when setting up a job at the correct height.  In theory, I 
could laser engrave 3D objects by using the Z axis as well, but I don't 
plan on using any Z motion in my laser G code, other than maybe a fixed 
Z offset at the beginning from the homed Z position is I decide to have 
a hardware Z=0 with relative offsets from that for each job.  I also 
plan on a light duty 4th axis for laser cutting round objects.  One of 
my production jobs requires laser cutting and embossing cylindrical tubes.

For reduced power settings, I'll pulse width modulate a signal to turn 
the laser on and off fairly quickly.

Many people would assume that it'd be easier and faster to draw 
something in CorelDraw and "print" it on the laser, but I hate it, and 
would much rather have direct control of the G code.  The CorelDraw 
print driver for the laser may be faster when making one or two of 
something, but it gives me no control over the order in which features 
are cut on the laser, which results in clumsy production jobs that are 
difficult to run because the order of subsequent steps are random, and 
there is a lot of wasted motion.  I want the control that I get writing 
G code by hand, in a logical progression.  To some extent, this is an 
extension of the lack of control I have in Windows, compared to Linux.  
I think it's more of a philosophical difference than a technical difference.

Sorry, but I haven't implemented any of this LinuxCNC laser stuff yet, 
so I have only this generic advice and no specific LinuxCNC example code.



On 04/29/2016 08:29 PM, Danny Miller wrote:
> Having some preliminary thoughts about LinuxCNC's appropriateness to be
> a laser cutter, like 120W CO2.  The other option is the open-source
> Lasersaur or Axecut.   Those aren't particularly advanced trajectory
> planners or anything.
>
>Can it be a good tool for lasering?
>
> I did see where some people had done it with some hacks, but I don't
> know how practical they are.  There was something about using a negative
> Z-value to turn on the laser.
>
> A lot of things come to mind.
>
> One, often the laser needs to turn on and off quickly, without
> stopping.  If it's technically implemented as a Z-move, it would slow to
> move the nonexistent Z-axis.  Would that work by just changing the
> Z-acceleration to something ridiculously high?
>
> Two, sometimes we do reduce the cut power, to only mark the surface
> instead of cutting it.  Initially you reduce the depth of cut by
> increasing speed, but if it's paper, you can't increase the speed
> enough, you have to cut back on the power.  And the r

Re: [Emc-users] LinuxCNC as laser cutter?

[andy pugh]

On 30 April 2016 at 03:08, Ricardo Moscoloni  wrote:
> i would say yes!, i have an 80w laser with ubuntu8.04 and ben´s
> laserfreq.comp and some magic halstreamer implementation by ben that do
> rastering with lcnc that work very very!! well.

That always seemed to me to be being very clever in just the wrong
part of the system, whereas it could have been a lot less clever
upstream.

I actually made a start (I specialise in unfinished projects, where I
prove to myself that something is possible, then lose interest) on a
non-Gode rasterer that imported a graphics file and generated a
raster-motion directly whilst outputting a laser intensity in
base-thread real-time.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] LinuxCNC as laser cutter?

[Ricardo Moscoloni]

i would say yes!, i have an 80w laser with ubuntu8.04 and ben´s
laserfreq.comp and some magic halstreamer implementation by ben that do
rastering with lcnc that work very very!! well.
my testing with m62 still produces some deaccel in my particular machine,
but dont do further testing due to lack of time in this production machine.
is old hardy, i wasnt able to mount lucid due to the machines old pc mb, to
test new tp but i encourage you to take the tour!.
http://www.buildlog.net/forum/viewtopic.php?f=16&t=557
to anyone reading this with some programming skills i will glad to see it
bundle that into lcnc
regards
rck


2016-04-29 22:48 GMT-03:00 Bruce Layne :

> I still haven't built my 3' X 5' 80W CNC laser, but it'll be controlled
> by LinuxCNC when I do.  I've had a big pile of laser parts for almost
> three years.  Maybe later this summer, if I finally find some mojo.
>
> LinuxCNC is better for cutting and embossing/engraving lines. LinuxCNC
> is not good for raster laser engraving.  Most of my laser jobs are
> cutting and light scoring which are essentially vector jobs, but I do
> have a few logos that are currently raster engraved on a friend's laser,
> which is essentially operating as a Windows printer using a proprietary
> printer driver, under CorelDraw.  My logos are simple, made of solid
> shapes, and I expect to render them as vector engravings by outputting
> vector image files from Inkscape.  That's the plan, anyway.  If you want
> to laser engrave photographs, you will probably need some way to raster
> engrave.  In that case, LinuxCNC may not be a good option for you.
>
> I've seen a few CNC lasers that used the -Z hack to turn the laser on,
> and that does have a certain simplicity, but I think it's too kludgey
> with too many tradeoffs and undesirable behaviors from the trajectory
> planner.  I plan on using M codes to turn the laser on and off.  I also
> plan on using the Z axis to drive stepper motors to jog the table
> elevation when setting up a job at the correct height.  In theory, I
> could laser engrave 3D objects by using the Z axis as well, but I don't
> plan on using any Z motion in my laser G code, other than maybe a fixed
> Z offset at the beginning from the homed Z position is I decide to have
> a hardware Z=0 with relative offsets from that for each job.  I also
> plan on a light duty 4th axis for laser cutting round objects.  One of
> my production jobs requires laser cutting and embossing cylindrical tubes.
>
> For reduced power settings, I'll pulse width modulate a signal to turn
> the laser on and off fairly quickly.
>
> Many people would assume that it'd be easier and faster to draw
> something in CorelDraw and "print" it on the laser, but I hate it, and
> would much rather have direct control of the G code.  The CorelDraw
> print driver for the laser may be faster when making one or two of
> something, but it gives me no control over the order in which features
> are cut on the laser, which results in clumsy production jobs that are
> difficult to run because the order of subsequent steps are random, and
> there is a lot of wasted motion.  I want the control that I get writing
> G code by hand, in a logical progression.  To some extent, this is an
> extension of the lack of control I have in Windows, compared to Linux.
> I think it's more of a philosophical difference than a technical
> difference.
>
> Sorry, but I haven't implemented any of this LinuxCNC laser stuff yet,
> so I have only this generic advice and no specific LinuxCNC example code.
>
>
>
> On 04/29/2016 08:29 PM, Danny Miller wrote:
> > Having some preliminary thoughts about LinuxCNC's appropriateness to be
> > a laser cutter, like 120W CO2.  The other option is the open-source
> > Lasersaur or Axecut.   Those aren't particularly advanced trajectory
> > planners or anything.
> >
> >Can it be a good tool for lasering?
> >
> > I did see where some people had done it with some hacks, but I don't
> > know how practical they are.  There was something about using a negative
> > Z-value to turn on the laser.
> >
> > A lot of things come to mind.
> >
> > One, often the laser needs to turn on and off quickly, without
> > stopping.  If it's technically implemented as a Z-move, it would slow to
> > move the nonexistent Z-axis.  Would that work by just changing the
> > Z-acceleration to something ridiculously high?
> >
> > Two, sometimes we do reduce the cut power, to only mark the surface
> > instead of cutting it.  Initially you reduce the depth of cut by
> > increasing speed, but if it's paper, you can't increase the speed
> > enough, you have to cut back on the power.  And the required power will
> > change inside the document.  How would that get specified, just with a
> > differing Z-depth?
> >
> > When not at the specified speed due to acceleration limits, the software
> > needs to reduce the power to avoid delivering more energy/mm than the
> > user specified.  Actually this sounds like the easiest part

Re: [Emc-users] LinuxCNC as laser cutter?

[Bruce Layne]

I still haven't built my 3' X 5' 80W CNC laser, but it'll be controlled 
by LinuxCNC when I do.  I've had a big pile of laser parts for almost 
three years.  Maybe later this summer, if I finally find some mojo.

LinuxCNC is better for cutting and embossing/engraving lines. LinuxCNC 
is not good for raster laser engraving.  Most of my laser jobs are 
cutting and light scoring which are essentially vector jobs, but I do 
have a few logos that are currently raster engraved on a friend's laser, 
which is essentially operating as a Windows printer using a proprietary 
printer driver, under CorelDraw.  My logos are simple, made of solid 
shapes, and I expect to render them as vector engravings by outputting 
vector image files from Inkscape.  That's the plan, anyway.  If you want 
to laser engrave photographs, you will probably need some way to raster 
engrave.  In that case, LinuxCNC may not be a good option for you.

I've seen a few CNC lasers that used the -Z hack to turn the laser on, 
and that does have a certain simplicity, but I think it's too kludgey 
with too many tradeoffs and undesirable behaviors from the trajectory 
planner.  I plan on using M codes to turn the laser on and off.  I also 
plan on using the Z axis to drive stepper motors to jog the table 
elevation when setting up a job at the correct height.  In theory, I 
could laser engrave 3D objects by using the Z axis as well, but I don't 
plan on using any Z motion in my laser G code, other than maybe a fixed 
Z offset at the beginning from the homed Z position is I decide to have 
a hardware Z=0 with relative offsets from that for each job.  I also 
plan on a light duty 4th axis for laser cutting round objects.  One of 
my production jobs requires laser cutting and embossing cylindrical tubes.

For reduced power settings, I'll pulse width modulate a signal to turn 
the laser on and off fairly quickly.

Many people would assume that it'd be easier and faster to draw 
something in CorelDraw and "print" it on the laser, but I hate it, and 
would much rather have direct control of the G code.  The CorelDraw 
print driver for the laser may be faster when making one or two of 
something, but it gives me no control over the order in which features 
are cut on the laser, which results in clumsy production jobs that are 
difficult to run because the order of subsequent steps are random, and 
there is a lot of wasted motion.  I want the control that I get writing 
G code by hand, in a logical progression.  To some extent, this is an 
extension of the lack of control I have in Windows, compared to Linux.  
I think it's more of a philosophical difference than a technical difference.

Sorry, but I haven't implemented any of this LinuxCNC laser stuff yet, 
so I have only this generic advice and no specific LinuxCNC example code.



On 04/29/2016 08:29 PM, Danny Miller wrote:
> Having some preliminary thoughts about LinuxCNC's appropriateness to be
> a laser cutter, like 120W CO2.  The other option is the open-source
> Lasersaur or Axecut.   Those aren't particularly advanced trajectory
> planners or anything.
>
>Can it be a good tool for lasering?
>
> I did see where some people had done it with some hacks, but I don't
> know how practical they are.  There was something about using a negative
> Z-value to turn on the laser.
>
> A lot of things come to mind.
>
> One, often the laser needs to turn on and off quickly, without
> stopping.  If it's technically implemented as a Z-move, it would slow to
> move the nonexistent Z-axis.  Would that work by just changing the
> Z-acceleration to something ridiculously high?
>
> Two, sometimes we do reduce the cut power, to only mark the surface
> instead of cutting it.  Initially you reduce the depth of cut by
> increasing speed, but if it's paper, you can't increase the speed
> enough, you have to cut back on the power.  And the required power will
> change inside the document.  How would that get specified, just with a
> differing Z-depth?
>
> When not at the specified speed due to acceleration limits, the software
> needs to reduce the power to avoid delivering more energy/mm than the
> user specified.  Actually this sounds like the easiest part, presuming
> we can get an accurate instantaneous speed.
>
> All power adjustments come via a PWM pin.
>
> Danny
>


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Re: [Emc-users] LinuxCNC as laser cutter?

[andy pugh]

On 30 April 2016 at 01:29, Danny Miller  wrote:
> There was something about using a negative
> Z-value to turn on the laser.

M62 works better and does not break blending.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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[Emc-users] LinuxCNC as laser cutter?

[Danny Miller]

Having some preliminary thoughts about LinuxCNC's appropriateness to be 
a laser cutter, like 120W CO2.  The other option is the open-source 
Lasersaur or Axecut.   Those aren't particularly advanced trajectory 
planners or anything.

  Can it be a good tool for lasering?

I did see where some people had done it with some hacks, but I don't 
know how practical they are.  There was something about using a negative 
Z-value to turn on the laser.

A lot of things come to mind.

One, often the laser needs to turn on and off quickly, without 
stopping.  If it's technically implemented as a Z-move, it would slow to 
move the nonexistent Z-axis.  Would that work by just changing the 
Z-acceleration to something ridiculously high?

Two, sometimes we do reduce the cut power, to only mark the surface 
instead of cutting it.  Initially you reduce the depth of cut by 
increasing speed, but if it's paper, you can't increase the speed 
enough, you have to cut back on the power.  And the required power will 
change inside the document.  How would that get specified, just with a 
differing Z-depth?

When not at the specified speed due to acceleration limits, the software 
needs to reduce the power to avoid delivering more energy/mm than the 
user specified.  Actually this sounds like the easiest part, presuming 
we can get an accurate instantaneous speed.

All power adjustments come via a PWM pin.

Danny


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