Machsupport Forum
General CNC Chat => Show"N"Tell ( Your Machines) => Topic started by: p00ky on January 17, 2013, 04:55:46 AM
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Hi there,
I recently got hold of one of these cheap DC-K40 china lasers, I had read many posts about them, mainly about the terrible Moshi Software, but also about how the main controller boards tends to die quite quickly. Sure enough, within 2 hours of setting it up, the Moshi software fed the machine some erroneous code, the head decided to bang its self on the bottom of the Y axis repeatedly until I managed to switch the machine off. When I started it up again it was clear the controller had croaked. The seller didn't want to send a replacement board (I don't know why) but gave me a £50 refund. Being that this was all the money I had I bought a tb6560 to control it (yes I am aware these boards have some issues too, but no money for DSP) and started to follow the instructions here.......
http://www.cnczone.com/forums/general_laser_engraving_cutting_machine_discussion/149028-conversion_tutorial_dc-k40_tb6560_blue_board_ebay_non-professionals.html
Everything went smoothly until I went to wire up the laser to fire from the Z axis. I realised that the markings on my laser supply are different. In the original tutorial he connected the "TH" on the laser supply to "Serial Pin 4"(Pin25 on LPT) but my laser doesn't have "TH". The laser firing is done from a connection marked "L"(5v) and "G"(ground I assume), when this connection is made the laser fires, in fact even the test fire button is connected here.
Here are a few Pics
(http://dc617.4shared.com/img/lA6c5WMD/s3/DSCF9181.JPG)
(http://dc617.4shared.com/img/io0otZje/s7/DSCF9184.JPG)
I have posted on the original tutorial page and although there has been a lot of views so far, no advice has come back so far so I thought I would post here too, as you guys tend to know what your talking about too :)
I'm quite new to electronics, and all I know is what I've taught myself, but that means when I hit a brick wall, I'm truly stuck.
Anyways thanks in advance, any help would be greatly appreciated.
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There is no absolute guarantee that the markings on your PSU board are correct as there is no international standard but this is way I would connect it.
Tweakie.
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With regard to interfacing with Mach3 my notes here may be of interest http://www.cooperman.talktalk.net/files/27_files/Page652.htm
Tweakie.
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Hi thanks for quick reply, may I just clarify what your saying with this picture
(http://dc144.4shared.com/img/a85kSUx6/s3/0.32687457879633697/psu1aaa_Modified.jpg)
This is what you mean right? I've put the original instructional jpg in the bottom corner so you can check.
I understand what your saying about the no guarantee, I'm willing to face the consequences :)
Thanks Again
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Connect the GND directly to GND and not through the spindle relay connection.
For the TTL - either choose an LPT Output pin that is not used by your stepper motors (for M10P1 / M11P1 control of the laser) or the Z axis Direction pin if you are taking that route.
If your pin 4 is Z axis Direction then Mach3 will set this pin high or low depending on your GCode Z axis +/- moves. In turn the laser beam will be switched on or off.
Tweakie.
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Hi again,
Worked beautifully!
Took me a little while to implement as I wanted to do a few checks etc before taking the plunge, but all went very well & I'm very happy.
Thanks
I've been checking out your website, there's a lot of good stuff there, so I shall have to do some more reading. Your machine looks awesome. These forums should be glad to have someone as clued in as you.
Anyways that's enough of all that, I'm off to burn things :)
Thanks again.
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Thats great, I am really pleased that you have got it working ;)
For the long-term, there are a couple of other points you may wish to consider…
It would be prudent to use and opto-isolator (or similar buffer) in the TTL connection to your laser PSU. This would offer a reasonable degree of protection to your controller / computer should the PSU suffer a catastrophic failure. This may also prevent the TTL logic conflict if your ‘Test’ button is used.
If using the Z axis Direction pin (rather than an output#) it may be beneficial to include your spindle relay (normally open contact) in series with the PSU protection circuit. This will prevent the laser being turned on (accidentally at start-up) unless a GCode M3 command has been issued – it will also allow (depending on the Mach3 configuration) the laser to always be turned off at program end or if the e-stop or limit switches are invoked.
Personally, I now much prefer using the M10P1 / M11P1 command set with an Output# as this is a much neater and safer way of operation.
Tweakie.
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I shall certainly look into all that you have suggested, I think I have an optocoupler somewhere around here :)
Thought I would share a pic of its first proper burn, obviously a few more tweaks required, I was tweaking bits and bobs through this cut, that's why some of the burns etc are a little deeper in places and there's a few mistakes, perhaps gcode, perhaps missed steps, but she's a runner and that's the main thing, I think it's time for a full stop. :)
(http://dc252.4shared.com/img/wShgkQ1X/s7/0.5076431647756681/DSCF9188.JPG)
Thanks again for all your help
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Connect the GND directly to GND and not through the spindle relay connection.
Tweakie.
Hey Tweakie
I have the exact same power supply. You said "Do Not Hook The Ground Wire to the Spindle GND". So the wire I soldered to the board (GND) hook to the ground what? Do I hook to the ground on the board next to the Power supply or the ground on the laser power supply? The info I'm following is on CNC forum on retro fitting to a blue board. I soldered a wire to the 4 pin on the 25 pin hookup on the bottom of the board. The instructions say hook that wire to (TH or L). Mach3 is working the motors just fine. My problem is this laser hook up. Forest Gumping my way through this.
Thanks in Advance
Jeff
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Hi Jeff,
I am not sure of your wiring setup so can't comment on your question.
What I am saying is do not use the spindle relay to switch the laser on / off by disconnecting the GND connection to the laser PSU.
Tweakie.
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I have the exact same setup as the "p00ky" has. I have my "Z" on pin 4. I have setup the Laser to run off the Z up and down. My problem is even when Z is pulled up I still get laser fire, not much but enough. The laser is not totally disengaging so on travel I get burn lines. No big deal with my router churning away it has been pulled up, but a big deal with a laser though. I was wondering if there is a way to put something in line that would either be on or off not variable?
Thanks Tweakie
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Hi Jeff,
Perhaps the GCode M11P1/M10P1 commands are the way forward - it is the system I now use.
This document and the attached comments refer http://hobbycncart.com/publ/cikkek/mach3_temaju_cikkek/switching_a_laser_under_mach_control/8-1-0-29
Hope this helps.
Tweakie.
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Hey Tweakie,
I read your write up on your web site about using the Z axis as the switch for the Laser. That looks to me the way to go. Using the Spindle Relay is not working out on the Blue Board. I get trace lines left by the laser when it jogs from cut to cut. So which one(s) do you use ZA+ ZA- ZB+ ZB- and what should I connect the GND too? Do I need to use Mach3 Mill or Mach3 Plasma?
Thanks Tweakie
Jeff
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Hi Jeff,
If you want to use the Z axis then it's the Z Axis direction pin# (Config. / Ports & Pins / Motor Outputs). GND is connected to the breakout board GND.
(please be aware that all the axis direction pins retain state (hi / low) until that particular axis is moved in the opposite direction).
Tweakie.
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I new that. Had a brain fart when I wrote that asking what pin to use on the output for the motor ;D. I found a video of a guy who used the "Mist/Pump" part of Mach3 to make sure the laser was off when it should be off. I will figure out sooner or later what will work on this thing.
Thanks
Jeff
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first off, thanks for the wiring Tweakie!! I have been high and low trying to find a pinout for this power supply, contacted the seller and the manufacturer. apparently they only make them and its up to others to figure out how to use it...
anyway, did you ever figure out how to fix the firing problem? Mine is doing the EXACT same thing, the laser fires on Z down, and sputters on Z up leaving little trails on the rapids and it's driving me crazy. My wiring is exactly as in the diagram except on my board its pin 6 for Z direction. Any suggestions would help a lot. Thanks in advance...
derrick
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first off, thanks for the wiring Tweakie!! I have been high and low trying to find a pinout for this power supply, contacted the seller and the manufacturer. apparently they only make them and its up to others to figure out how to use it...
anyway, did you ever figure out how to fix the firing problem? Mine is doing the EXACT same thing, the laser fires on Z down, and sputters on Z up leaving little trails on the rapids and it's driving me crazy. My wiring is exactly as in the diagram except on my board its pin 6 for Z direction. Any suggestions would help a lot. Thanks in advance...
derrick
Sorry no, I cannot get it to stop firing the laser. I just about gave up on the whole thing. $500.00's of disappointment. I do know for a fact I'm getting a 0.01v to the pin 14. I'm guessing if it's not exactly 0.0v it will fire the laser - super sensitive to this. Everyone I ask will not give you a simple response. Go read here or go read this, that's not helping. I have followed the conversion to the "T" and no go for me.
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Hi Guys,
It sounds to me like you are experiencing a difference in potential between the GND connections between your computer LPT port and the machines PSU GND.
The LPT port’s pins 18-25 are GND and one of these pins must be connected to the laser PSU’s GND point (adjacent to the TTL(L) signal input as shown in my earlier diagram),
This should resolve the problem of the laser firing when it should be off.
Tweakie.
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Mine is wired from the ground on the driver board through the spindle relay and to the ground on the power supply. does that make a difference? I was getting ready to either put resistor on the line or thought maybe it was noise and was thinking of maybe an optocoupler.
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My advice is to take the connection directly from the PSU GND to the LPT GND not going through the spindle relay.
If you need to use the spindle relay then take the interlock protection circuit through the spindle relay.
Tweakie.
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Tweakie,
Thank you sir, you are truly brilliant! the mechanicals of my design loosely based off of Barton Dring of buildlog.net 2.x laser cutter, but since i a using a cnc controller board instead of a dsp i have had issues getting it to work properly. but had i not ran across some of your other postings across the web about using "magic z" to control the firing, i would have not able to get this far!
i love to build stuff and i have a very, very limited budget which causes much conflict to be sure. without people like you and Mr. Dring paving the way, i would surely be in the stone age.
again, thanks!
-derrick
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It sounds to me like you are experiencing a difference in potential between the GND connections between your computer LPT port and the machines PSU GND.
The LPT port’s pins 18-25 are GND and one of these pins must be connected to the laser PSU’s GND point (adjacent to the TTL(L) signal input as shown in my earlier diagram),
This should resolve the problem of the laser firing when it should be off.
Sadly, it does not... I went this morning and wired up the new board (pin7, pin25) gave it a test drive. BTW if anybody is interested, the TB6600 vs TB6560 believe it or not makes a HUGE difference in the sound of the machine. so much quieter now...
except for, it won't stop firing!
here are the details: it is wired exactly as in the diagram. before i was pulling the ground from the board, now it is soldered right to pin25.
what it does:
1) test fire button works just fine.
2) red laser led barely lights up when the laser control screw terminal is plugged in and goes out when unplugged. it brightens to full on when the test button is pressed. this is regardless of whether the pot is wired in or not and/or the setting of the pot.
3) laser is completely off until flood(relay) is on and then the tube sputters or flickers burning lines wherever it goes.
4) the only way to turn the laser off it to either unplug the screw terminal or to turn the pot down, in both cases of which the laser won't fire.
what I've tried:
1) two different computers
2) two different power supplies (i picked up this power supply because i thought there was a malfunction with the first which i bought used off ebay)
3) three different driver boards (expensive lessons learned!!!)
4) used pin 7 as both z direction and digital out
5) wired the power supply with and without potentiometer.
so if you have any advice or suggestions, that would be greatly appreciated. I am at a loss as to where to go from here. does the pin # make any difference? i am not to well versed in parallel ports and haven't used on since the days of the dot matrix printers; i'm a programmer not an engineer!
-derrick
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Hi Derrick,
Sorry to hear that you are still having problems with this.
I need more details, could you post (or email me) details of your connections (circuit) perhaps a diagram and pictures. The problem will be something simple but, so far, it is proving illusive to find. :)
Tweakie.
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ok, i didn't have time to draw a wiring digram, but it is wired exactly as the original diagram in this post, aside from using pin7 instead of pin4 (that's my Y pulse pin). here are a few pictures with some notations. in the picture with the label, the laser led is on (it looks brighter in the picture than it really is), but the laser is not firing because of the interlock.
(http://www.odditarium.com/content/storeage/photo-3.jpg)
wiring to the board
(http://www.odditarium.com/content/storeage/photo-2.jpg)
my wiring
(http://www.odditarium.com/content/storeage/photo-1.jpg)
firing the laser, the led lights more
The wiring is a bit of a mess right now because i haven't done any cable management until everything works properly
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Hi Derrick,
If I am understanding correctly, you are using LPT Pin 7 as your laser trigger.
How is that configured in Mach3 Config / Ports & Pins / Motor Outputs ?
Tweakie.
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sorry, out of town for last two days. i have pin 7 configured as z-dir, not inverted. i also tried to use pin 7 as digital out, but that didn't make any difference either.
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Hi Derrick,
Try changing your Mach configuration so pin 7 is active low (inverted).
Tweakie.
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Hello Tweakie,
i gave that a try this morning an still a no go. when i get home tonight i am going to test the actual parallel port and check the voltage coming out of the computer.
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Hi Derrick,
Perhaps you could perform this simple test…
Remove the red wire (connected to LPT Pin 7) from your laser PSU. With the Pot set to < ¼ power level, switch on the system – does the laser fire continuously ??
Measure the voltage between the “L” terminal and the “G” terminal on your PSU (with the system powered up and the red wire still disconnected) is it 5 Volts ??
Tweakie.
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Hello Tweakie,
So this is where i now stand... yesterday i had the idea that the problem might lay in the board itself because as i was getting ready to conduct your tests, i noticed that the laser led was dimly on when the board was not connected to the parallel cable! so thinking that there might be some stray voltage the board, i went to radio shack and got a female parallel port head and proceeded to solder a new cable leaving 7 and 25 free to wire directly into the laser psu. after spending all night with that crappy radioshack junk (had to re-solder because the connections kept coming undone), i went out and plugged it in and ...... same thing. so i went and hit everything with an ohm meter this is what I'm getting:
L - G on psu 1/4 power: 0.0v
G - red wire (disconnected): 3.10 - 3.50v
pin7 - 25 (laser fire): 0.15v
pin7 - 25 (laser off): 3.1 - 3.40v
switched to pin 8 and same results.
switched to pin 7 as digital0 out, same results
so my conclusion is that it appears that my parallel port operates on 3.3v and fluctuations are causing the laser to think that it's being fired super fast because its fuzzy around the ttl/tth cutoff. Does this sound about right? I read that your parallel port mode in the bios could make a difference, but in the bios of the machine I'm using (emachines t5088) there are no options to change the parallel port mode (super basic settings). Is it possible that i just may need to pick up a parallel card? or is there a trick that could be done with a resistor to pull it up to 5v without damaging the p-port?
thanks,
derrick
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SOLVED!!!!!
the whole problem was from the fact that the onboard parallel port was 3.3v. I spent so much time assuming that i had a signal, that i didn't check to see what the actual voltage was. now it works exactly as it was supposed to!!
for those who run across this thread or have this same problem, i ordered this parallel port from newegg.com for around $14 with free shipping (which is why this post is 10 days later. shouldn't have cheaped out and paid to get it sooner!)
http://www.newegg.com/Product/Product.aspx?Item=N82E16815166006&Tpk=15-166-006 (http://www.newegg.com/Product/Product.aspx?Item=N82E16815166006&Tpk=15-166-006)
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I am pleased you have found the problem ;)
Tweakie.
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Hey Tweakie!
I solved my Laser issue! I dumped the Blue board and went with break out board & 2 driver boards for X & Y. I forced myself to read the MACH 3 manual ::). I ran the Z DIR pin into the Relay on the Break Out Board. I then ran the Output of the Relay to the "L" on my PSU. I turned on the Spindle Control on MACH 3. No Ground wire needed. IT WORKED! This is not exactly what I wanted it to do "REALLY :o?!?" I wanted it to be variable controlled but I will take this win anytime!! I will figure that out later.
Thanks Tweakie for your help
Jeff
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SOLVED!!!!!
the whole problem was from the fact that the onboard parallel port was 3.3v. I spent so much time assuming that i had a signal, that i didn't check to see what the actual voltage was. now it works exactly as it was supposed to!!
for those who run across this thread or have this same problem, i ordered this parallel port from newegg.com for around $14 with free shipping (which is why this post is 10 days later. shouldn't have cheaped out and paid to get it sooner!)
http://www.newegg.com/Product/Product.aspx?Item=N82E16815166006&Tpk=15-166-006 (http://www.newegg.com/Product/Product.aspx?Item=N82E16815166006&Tpk=15-166-006)
Glad to see you got yours working! Are you able to vary the Laser Power Output "Variable" or is it ON - OFF like mine now? I want it to be variable power.
Going to order one myself, we both had the exact same issue. Could you post screen shots of you MACH 3 setup for this Laser?
Thanks in Advance
Jeff