My adventures with Auggie.

[tweakie]

I had not actually seen a 57CNC until this week and despite reading the Pokeys manual a few times there was still a lot that didn?t make any sense to me. As it turns out this clever little board virtually sets itself up and much to my surprise it was communicating with my laser equipped machine before I knew it. There seemed to be a little confusion between the Y and B axis regarding the limit switches but as they all operate as intended I did not investigate further.
Because I will be using the 57CNC to operate an existing machine using just the DB25 connection it needs to be pin compatible and I have found a couple of issues. The PWM signal is sent on pin 14 and I need it to be on pin 16 and in addition, it is active high and I need it to be active low. Despite my best efforts I cannot re-assign the PWM signal to another pin or invert the PWM polarity within the 57CNC set-up so a hardware solution is currently in progress.

Tweakie.

[tweakie]

Now I appreciate that this is bit unorthodox but I have cut into a ribbon cable connector and using an opto-isolator I have inverted the PWM signal and transferred it from pin 14 to pin 16.
To be on the safe side, I am limiting the current drawn from the 57CNC pin 14 to around 5mA (which is sufficient to drive the LED in the PC123 opto-isolator) and the Vcc for the opto-transistor is provided by the pull-up resistor in my laser psu input.

A simple, quick and in-cable solution which requires no additional power source.

Tweakie.

EDIT:  Please see post #8 for an update on this.

[tweakie]

It?s alive !  :D

This is my first test run with Auggie and the laser powered up.

Tweakie.

[tweakie]

A couple of observations ? not problems.

1) The splash screen is not totally erased when the laser screen opens.
2) Auggie crashes when loading an image file using the AUGS button.

This only happens with the workshop WinXP computer, neither issues happen on a Win10 computer. As said it is not a problem to me as image compilations would not be made on the workshop computer and the remnants of the splash screen can be removed by changing to the default screen and back again, if I was really fussy.

Tweakie.

[ArtF]

Hi Tweakie:

  You know, its a testament to your skill that you got a laser burning an engraving
without a single question on Auggies internals. I hadn't seen that done before.
Congrats, thats a real achievment, Im pretty impressed. The burn looked good too!

  Ill be interested in how you find the true 3d burning when you figure it out..

  I dont run XP anymore, but Ill look into the problem and see if I can see an issue I can
correct there. Same with images, they should load fine, though they are a bit memory
hungry.. Auggie is a beast I kinda tame to do what I need at any given time, few of us
are users of it, but I kinda like it when I run it. Im in the design process to make it do
3d printing by laser, but Ill wait to see how that works out..

Yell as you get into trouble in Auggie, but based on your progress so far I guess
I needn't worry..

Art

[tweakie]

Thanks for the kind words Art but I am really not that smart ? I watched your video?s and read many of the Members posts here before I even attempted to get Auggie working  ;)

Tweakie.

[tweakie]

It is now evident to me that there are just sooo many different settings and adjustments that can be made within Auggie that it could take some while to achieve the optimum results for any particular process or material.

Here are a couple of attempts, using different settings, with the same 8 bit image.

Tweakie.

[ArtF]

I like all three. :) , the circular one is kinda nice.

  In Auggie your free to make any GCode shapes, so sine waves, hilbert curves and such in Gcode
would all create interesting back pattern shapes in the burned photo. I suspect its easy to come up
with texturing patterns as well. 

  As to settings, there are a lot. Then there's macros you can write to do special things you
may want. Your Gcode can call macro's or even have C script in it, so may special processes
can be automated. Auggie is nothing if not versatile. With versatility though, comes 
complexity so it can be a bit much to figure out all the ins and outs. ( To be honest I'm still
figuring them out myself.. I only burn with Auggie in the winters).

  How do you find the "only burn with g1 motion" feature? Its my favorite thing with laser.
Any suggestions to make it better? Does your power vary properly during acceleration to
smooth out burn marks typically found in non-corrected motion? Ill be back at Auggie when
Vexx is released so feel free to plug any suggestions you may have.

Great work!, keep showing us the results, I think your way ahead of the curve.

Art

[tweakie]

Hi Art,

Yes indeed sir the ?only burn with G1 motion? works very well and of course, avoids codes such as M62/M63 etc.
So far I think I have only had the acceleration and deceleration zones outside the work area but my machine has an LED which varies in brightness with the PWM signal. I can observe the tickle pulse during the Accel / Decel zones and the PWM tracking up and down within in the image areas.
I have had to re-think my earlier idea of inverting the PWM signal using an opto and reverted to using a transistor which exhibits a much smaller propagation delay. The delay in the opto on-time was noticeable from close-up inspection of the work.

It?s going to take me forever to learn all the features of Auggie (I have been using Mach for over 10 years and I still don?t know the half of that) so I don?t think I will be making any suggestions for improvements any time soon.

Tweakie.

[ArtF]

Tweaky:

  Ill make note to check the PWM, I thought it was invert-able. Of course simply inverting the power demand would invert it,  I cant recall if I allowed that to happen. Ill check at next opportunity. Sounds like a simple software fix..

  So long as your having fun with it, it fulfills its purpose. It was written to be a general experimenters
CNC controller. I'm one of those who is always playing with a new idea, usually half baked and failing,
but hey, M3's driver came from such half baked idea's :) ,so I needed such a platform, Mach3
did it for me for over a decade, but that missing PWM capability made Auggie necessary. Its Gcode
isn't as complete as Mach3's, but its scripting and macro capability blows M3 out of the water for
experimentation involving weird or unknown devices. 

  More will be added to it as I play with a few idea's this winter.

Have fun,
Art

   

[tweakie]

Hi Art,

Every indication is that PWM is invertible and there are check boxes to that effect within the 57CNC config. but I spent a good 2 hours trying and it defeated me.
I have now had time to test my hardware solution and it works just fine for me (I was initially concerned about using a transistor in this manner with possible tri-state logic but all is well).

Tweakie.

[ArtF]

Tweaky:

Yeah, its probably fine, any lag you see may be Auggies fault, its a tricky thing to try to linearize the pwm over the
accel period so it can appear a bit laggy. The config settings of min and max power can help as
they set the actual start power point(  you set to the PWM power at which laser actually starts
coming out, this can be pretty high on some laser, or low on others. ), this helps in the linear aspect of the accel power correction.

Art

[tweakie]

I have just tried some vector cutting as a test of the varying PWM with velocity. My test Gcode is approx. 50/50 arc?s and straight lines so should be a good test.
The results were not quite what I was expecting?
At a maximum set feed-rate of 6000 I was only achieving a max. of 30% PWM but at a maximum set feed-rate of 500 then I was achieving a max. of 100% PWM.
At first sight it appears that the PWM duty cycle is reducing as velocity increases ? the exact opposite of what I was expecting.

I am wondering if I have screwed something up in my software settings somewhere ?

Tweakie.

[ArtF]

Hi Tweak:

  Well, its hard to say. But, let me explain how that works.
Lets say you have set a max speed of 6000. Whenever the head is moving
in a G1, it computes the speed for that ms by the number of steps it will
take during that ms ( on each axis so vectored to a directional speed. ).

  So if, just like the days of M3's CV modes, you command a speed which
the head doesn't truly reach, the speed will never hit 100%. If I run RoadRunner
for example, and the max speed it hits is 340mm/sec due to speed/accel/Jerk
constraints in the run, and I have commanded 1000 as a feedrate, the max PWM
during that run at its fastest point will be 34%. Commanding a higher feedrate will
further lower the laser power reached.

  So in a vectored mode, the feedrate commanded is a master setting of top
power as well as speed by virtue of end resultant speed. What I do is a test run in air,
note the speed actually reached, and command that as the max feedrate.
In this way it does hit 100%.

  Trouble is, it may only hit 100% in a straight away and less than that in any other area.
The laser meanwhile is adjusting for max power on a 0-100% scale on actual feedrate
divided into the max feed-rate commanded.

  Now, we also run into a problem of linearity, most lasers are not linear in power,
most specially at very low power. You can for example get 0% until a PWM of 15%
or even 40% on some lasers. They seem to vary widely in this, glass tube lasers
usually have this at a high number as the turn on point is a bit high.

  SO in the config ( from memory) is a dual setting, min power and max power pwm.
This should be set for the lowest power to be the point of turn on. The highest may be set
for a safety ( I recommend 95% or so) as the highest the laser will go to. It may be set to
100 for many lasers, but some co2's are recommended not to go beyond 27ma or so
, so the setting is there to restrict it to that 27ma , you'd need to know what pwm sets it to
27ma is all ( trial and error will often suffice.).

  If the low is set too low, the start of a line will go away as the laser wont turn on till it reaches
a pwm of the laser plasma start point. The high setting as I say, is simply a safety milli-amp limit
for your laser.

  This can be important in variable accel power because as it slows to zero speed, the power ramp
will reflect the minimum turn on power to be zero, not actual pwm of zero. SO make sure you play
with those adjustments and command a feedrate that you can actually reach, not a feedrate that's
unreachable.

  I noted last time I used this ( to cut out a vine in paper ) that it needs a bit of work, it works but
I found it hard to tune the power/feedrate curve. I plan this winter to add a better way of calibrating
the power/speed curves so one can more easily find the sweet spot for a cut. My thought is that it'd
be better to allow a user to set a speed curve designed for that cut or machine.

  Because this can be hard to tune, there is a button on the laser panel to turn off this speed
correction. Its labeled "DistCor" and will turn off the acceleration checking. This will give you selected
power whenever it moves. This , of course, leads to burning in corners and slow area's just like my co2 laser
does when run from its firmware instead of Auggie.

  Most co2 laser engravers take care of this with speed, they try to do a constant speed as much as they can
and allow for burning too much on corners and slow areas. As they have low mass heads they can do a pretty
good job of constant speed most of the time. My laser is high mass, I have to use anti-jerk control
for smoothness and this is why distcor exists.  I have to use acceleration and jerk limiting, and this makes
full power lasing on vectors difficult. When tuned in by selecting proper feed and such the vectors seem to
work fine.

  So turn off DistCor and you should get full selected power during any ms of motion, kinda like Mach3's on/off
P commands without having to enter them. You can also slide the laser power slider even during a run for
fine correction.

  Lastly, the accel/jerk limits play a part as they control just how slow youll have to go in corners. If you adjust
Jerk Limits upwards, you make it faster on the curves, this is a hard one to tune, some may have jerk set to 5000,
I set mine quite frequently to 500,000 depending on what type of work Im doing on it.  It takes some experimenting
during a vector run to find your best jerk setting if your using DistCor to smooth out power.

  So this winter Ill be looking into better ways to smooth this out, perhaps with user settable speed/power curves
for better control of end power in various situations.  YaNvrNo is my main laser tester, and we both noticed that
vectors take some tuning to do and speed curves we discussed as a way of getting a better result.

  So, lots to play with there, turn off DistCor though and a vector cut is much easier and works more like the
normal engraver does and should mimic M3's P modes for on/off.

Yell if you dont have a DistCor button, Im pretty sure I put it in the release, its on my panel..


Let me know how you make out,

Art




 

 

 

 
 

[tweakie]

Hi Art,

Many thanks for the extremely detailed explanation. I had spotted the Distance Correction button but had no idea of it?s purpose or function. Once you mention it then it is obvious that I could not get anywhere near to the 6000 set feed-rate thus the reduced PWM ? it all makes sense now ? thanks again.

I am just loving the ?AUGS? button and Auggie?s variable PWM laser power control together with the ?S curve? Accel / Decel and motion from the 57CNC. My machine is loving it as well ? much quieter and smoother in operation which is certainly kind to all the mechanicals.  My 8 bit photo reproduction is going to be heading to new levels  ;D

Tweakie.