Benbox Laser Machines/CO2 Lasers/3D Printers

Hey Zax, import PLT not working with kicad plots.

I only tried one and get a continuous pop up of 'non fatal error' till I use task manager to kill the T2Laser process.
File i tried attached, it looks fairly basic at first glance so not sure where the error lies.


While I have your attention, you mention in the gerber import that you can load drill files, I was hoping I could use them to add pad holes to the copper pour as there is no option to do that with kicad as holes are another layer, but it didn't appear to image anything, is it just for boring holes perhaps ?

Ok I etched the board mentioned above and in general it was a success, I need to up the laser power a little and optimise the board a bit, there was nothing done to that one, I usually increase pad sizes for the through hole headers, vias and IC pads. I failed to do even the most basic checks on that one, I just pumped out a test design .. so the IC footprint is incorrect

Photo of a narrow SOIC28  with a match for scale. A couple of the trackes near the match head were improved with a sharpie pre etch as the exposure was pretty minimal and there were a few holes in the tracks in some area.
My photoresist is about 4 years past its use by date too, so it also had visible dark patches that did not etch fully .. very promising though.

Tomorrow, redesign and I might attempt a double sided board.

Using a 2500mW benbox running grbl 1.1f and latest T2, pcbs designed in Kicad.

I have some new thermal photoresist coming from china atm, currently though I am using Cape Fear Press Puretch film. Probably the same photoresist though I do not know yet.

Getting good results at feed 1000, laser max 26, bidirectional off, I was using 0.05mm resolution but I think it is overkill and takes around 35 minutes per square inch.
So I am just doing my first attempt at 0.1mm.

Most of the testing has just been done with a piece of film with both plastic layers attached, tried it held down with coins on the corner, microslope glass slide or a piece of 1.5mm glass on top and not noticed much difference.

Everything I do is SMD so aiming for at least a 0.5mm track with 0.5 clearance. Close to achieving it, I might have to 'detune' the focus yet or change a few more parameters.

Though this is a negative photoresist, with a laser you need to consider it positive, so isolation routing is of no use, flatcam is out, gerber2pcb is out, inkscape gcodeutils from a dxf source produces odd scaling.

I am using gerbers currently. Hope to try dxf or plt when I can work out how as I have no holes in my through hole pads currently. I would really prefer to vector trace instead of raster scan these.

I joticed in a search that others are using paint options, I will go back and have a read now
Just typing this as I am bored waiting for the next test to complete.

Attached a photo of the last few test runs on a piece of plastic to make the film more visible.

I have 2 versions of 1.1e listed.
One was no PWM and the other was "axis swap" neither of which I thought was suitable, I was thinking it was reversed for some reason.


Ah, 10000 line limit, that would be it.

purchased T2 It looks like it will save me a lot of hours installing other stuff if nothing else and I will bill it to someone else later

I found a config  file that seems to do a reasonable job. Basically ..

$0=10 (microseconds, Step pulse time: Sets time length per step. Minimum 3usec.)
$1=80 (milliseconds, Step idle delay: Sets a short hold delay when stopping to let dynamics settle before disabling steppers. Value 255 keeps motors enabled with no delay.)
$2=0 (mask, Step pulse invert: Inverts the step signal. Set axis bit to invert (00000ZYX).)
$3=0 (mask, Step direction invert: Inverts the direction signal. Set axis bit to invert (00000ZYX).)
$4=0 (boolean, Invert step enable pin: Inverts the stepper driver enable pin signal.)
$5=0 (boolean, Invert limit pins: Inverts the all of the limit input pins.)
$6=0 (boolean, Invert probe pin: Inverts the probe input pin signal.)
$10=3 (mask, Status report options: Alters data included in status reports.)
$11=0.010 (millimeters, Junction deviation: Sets how fast Grbl travels through consecutive motions. Lower value slows it down.)
$12=0.002 (millimeters, Arc tolerance: Sets the G2 and G3 arc tracing accuracy based on radial error. Beware: A very small value may effect performance.)
$13=0 (boolean, Report in inches: Enables inch units when returning any position and rate value that is not a settings value.)
$20=0 (boolean, Soft limits enable: Enables soft limits checks within machine travel and sets alarm when exceeded. Requires homing.)
$21=0 (boolean, Hard limits enable: Enables hard limits. Immediately halts motion and throws an alarm when switch is triggered.)
$22=0 (boolean, Homing cycle enable: Enables homing cycle. Requires limit switches on all axes.)
$23=0 (mask, Homing direction invert: Homing searches for a switch in the positive direction. Set axis bit (00000ZYX) to search in negative direction.)
$24=25.000 (mm/min, Homing locate feed rate: Feed rate to slowly engage limit switch to determine its location accurately.)
$25=500.000 (mm/min, Homing search seek rate: Seek rate to quickly find the limit switch before the slower locating phase.)
$26=250 (milliseconds, Homing switch debounce delay: Sets a short delay between phases of homing cycle to let a switch debounce.)
$27=1.000 (millimeters, Homing switch pull-off distance: Retract distance after triggering switch to disengage it. Homing will fail if switch isn't cleared.)
$30=1000 (RPM, Maximum spindle speed: Maximum spindle speed. Sets PWM to 100% duty cycle.)
$31=0 (RPM, Minimum spindle speed: Minimum spindle speed. Sets PWM to 0.4% or lowest duty cycle.)
$32=1 (boolean, Laser-mode enable: Enables laser mode. Consecutive G1/2/3 commands will not halt when spindle speed is changed.)
$100=80.000 (step/mm, X-axis travel resolution: X-axis travel resolution in steps per millimeter.)
$101=80.000 (step/mm, Y-axis travel resolution: Y-axis travel resolution in steps per millimeter.)
$102=80.000 (step/mm, Z-axis travel resolution: Z-axis travel resolution in steps per millimeter.)
$110=5000.000 (mm/min, X-axis maximum rate: X-axis maximum rate. Used as G0 rapid rate.)
$111=5000.000 (mm/min, Y-axis maximum rate: Y-axis maximum rate. Used as G0 rapid rate.)
$112=5000.000 (mm/min, Z-axis maximum rate: Z-axis maximum rate. Used as G0 rapid rate.)
$120=600.000 (mm/sec^2, X-axis acceleration: X-axis acceleration. Used for motion planning to not exceed motor torque and lose steps.)
$121=600.000 (mm/sec^2, Y-axis acceleration: Y-axis acceleration. Used for motion planning to not exceed motor torque and lose steps.)
$122=10.000 (mm/sec^2, Z-axis acceleration: Z-axis acceleration. Used for motion planning to not exceed motor torque and lose steps.)
$130=370.000 (millimeters, X-axis maximum travel: Maximum X-axis travel distance from homing switch. Determines valid machine space for soft-limits and homing search distances.)
$131=300.000 (millimeters, Y-axis maximum travel: Maximum Y-axis travel distance from homing switch. Determines valid machine space for soft-limits and homing search distances.)
$132=200.000 (millimeters, Z-axis maximum travel: Maximum Z-axis travel distance from homing switch. Determines valid machine space for soft-limits and homing search distances.)

except I have since changed $30 back to the default 255

I just grabbed your demo and I must say it beats anything else I have looked at so far hands down. I am running at 20/255 laser power and probably only need 30 I think, I am just testing with piece of film at the moment and not mounted it to pcb but it is discolouring it which is a good sign for a successful developing.

Are the guys etching on here using a photoresist or removing paint from a pcb ?

I think a photoresist method should be adequate resolution for me, I may well buy a smaller laser just for the job, while I was waiting on my A3 from banggood I ended up loading up a nano with grbl and removed the guts of an old roland plotter in my shed, chucked on a couple of pololus at 28V and have it running at 5000mm/min quite happily. It could happily shunt a 200mW laser around which is all i think i need. So I might save this slow 2500mW beastie for burning things.

Is there any way to offset an image  apart from mechanically within T2 ?
The board I am testing with is loading up on the far right of the frame (but etching on the left ?) and i was wondering if I could remove the offset, it is probably from creating the board in the middle of the kicad page and I could move it there too.

attached the little test board gerber if you are interested in looking.

Hi guys, first post.

I am an electronics guy and mostly bought this doohickey to expose negative PCB photoresist, so if anyone has done that with one of these etechers please let me know and save me some thinking

Machine arrived yesterday and I like to know where I stand before using them much. Might be errors below since this is my first day with this dodgy software, I could not find this documented anywhere despite several searches. So decided to have a look myself and document it, might as well place it here.
I have pulled the arduino out since it is easier, I have a board marked Mana SE.

Most useful image I can find I stole from ebay and added here http://imgur.com/rT7oieU


Hardware description Mana SE
-------------------------------

I have no jumper under the arduino, just an inductor and what appears to be a solderable jumper, PWM is always enabled.
The solderable jumper, one side is Vdd on the pololus, the other is 5v pin of the Nano, so I gather the pololu logic supply is different from the nano 5v regulated output. Suffuice to say, this link has nothing to do with PWM.

The inductor looks to be a stepdown supply operated by a TPS54331  http://www.ti.com/lit/ds/symlink/tps54331.pdf
sense resistors are 10k and 1160R so the output voltage seems to be set at 7.69V however I measured it as 5V 

This supply seems to drive the low voltage Vdd supply for the Pololus and the unused "servo" output supply, the Laser, "motor" connector and stepper drive voltages are both the straight 12V input.

These are a good chip apart from one nasty trait I know of, shorting the input wires together during operation (shutting input power) will blow the device mosfets, all good, just be careful with dodgy 12v input wiring. I recently stopped using these on a raspberry pi supply i designed for a client and swapped to an LT device due to a few failures, probably due to the chinese assembling the boards for the client and not using the nice low ESR caps I specified, replaced the chip and the caps with TDK's and had no issues.

There is a driver mosfet onbaord (gate drive resistor R1 = 100R) is an http://www.mouser.com/ds/2/196/irlr120npbf-936712.pdf
so rated for 10A, has nothing to do with the laser, it is low side switching for the "motor" output.

The servo control signal is also arduino D11, so this is fed directly to the laser, to the servo and controls a mosfet doing low side switching of the "motor" output.

Default pololu motor currents, the Y motor pair driver is set for 640mV and the X around 350mV so these have been factory set to reasonable values. Suspect they could be cranked up significantly for higher torque/speed.

The "bluetooth" connector RX and TX are the normal arduino RX/TX so you could monitor the serial comms from the CH340G directly on these pins.

Stock Software
----------------

Stock software is currently
Benbox Version 3.7.99

nano has no reset button and does not respond to the reset line, interesting, maybe a 'special' nano.
uses a CH340G driver and default 115k baud.

on power up it sends

benbox laser 3.1(c) mul 2015.06.06
start
ok
[2,3,5,6,-1,-1,-1,-1,11,11,-1,-1,320.00,320.00,1500,0]ok

the benbox software responds to this packet with a

$21 P-2


So the numbers you set up on page 2 Step,dir,min,max etc are obviously arduino port numbers for the most part.
ie Step 2,3  Dir 5,6 and laser 11

Speed .. if you traverse then this is the frequency of the step pulse.
No need to save, a change on the page is the speed of the next command
set high to determine maximums
These are with the default 320.0 ppm setting on page 2, setting the PPM higher still leaves you with a 3.68kHz top speed.

highest speed 3.7kHz (136uS high, 132uS low)
1000 = 1.31kHz (380/384uS)
2000 = 2.45kHz
10 = 13.3Hz

Step .. minimum step distance using the traverse buttons ? varys with how long you use the button and a short click is missed entirely.
also the value makes not a lot of sense, don't rely on it for accurate movement.
eg ..  1 = 14 pulses, 10 = 62 pulses


Laser .. D11 output. PWM frequency 490Hz
low light set to 16 default = 125uS pulse every 1.915mS
Minimum 1 = 8uS pulse
DO NOT SET TO ZERO .. this results in full power.
change by editing value then reclocking the low power 'on' button

Stock Gcodes.. ( I used https://en.wikipedia.org/wiki/G-code as a reference)

Laser off = M05 L0
Low on <power> = M3 L<power> P0

Traverse left distance <step> at <speed>
G91
G01 X-<step>L0 F<speed>

Traverse right
G91
G01 X<step> L0 F<speed>

A short click on button sends G91 with no G01 commands, a long hold repeats G01's

traverse Y is G01 Y<step> L0 F<speed>

Note that changing <step> seems to require 2 sends before it changes in the command sequence.
changing speed does not, odd.

Drew a diagonal line from 0,0 to 20,10 and ran it.
resulting command sequence, added comments after from standard gcode list

G21 // set to mm mode
G90 // absolute mode                                             
G92 // position register                                                 
M05 L0    // spindle (laser) power 0                                                                     
G00 X0 Y0 F1500      // rapid position to 0,0
G92 // position register
G00 X0.20 Y-0.20 F1500 // rapid go to line start (absolute)
G01 X19.90 Y-10.40 F1500 L100 // etch line to approx 20, -10 ( so front of the machine is a negative value)                   
G00 X0 Y0 F1500 // rapid return to 0,0
M05 L0 // laser off
G00 X0 Y0 F1500 // yet another rerun to 0,0 ?


TX output sends ok <cr> <lf> on a command


enough for now..