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Author Topic: DC-K40 Laser conversion issue  (Read 27548 times)

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DC-K40 Laser conversion issue
« on: January 17, 2013, 04:55:46 AM »
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




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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Re: DC-K40 Laser conversion issue
« Reply #1 on: January 17, 2013, 06:33:52 AM »
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.

Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

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Re: DC-K40 Laser conversion issue
« Reply #2 on: January 17, 2013, 06:51:54 AM »
With regard to interfacing with Mach3 my notes here may be of interest http://www.cooperman.talktalk.net/files/27_files/Page652.htm

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: DC-K40 Laser conversion issue
« Reply #3 on: January 17, 2013, 06:57:49 AM »
Hi thanks for quick reply, may I just clarify what your saying with this picture



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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Re: DC-K40 Laser conversion issue
« Reply #4 on: January 17, 2013, 08:27:56 AM »
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.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: DC-K40 Laser conversion issue
« Reply #5 on: January 17, 2013, 09:58:32 AM »
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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Re: DC-K40 Laser conversion issue
« Reply #6 on: January 17, 2013, 10:01:52 AM »
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.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: DC-K40 Laser conversion issue
« Reply #7 on: January 17, 2013, 02:35:58 PM »
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. :)




Thanks again for all your help
Re: DC-K40 Laser conversion issue
« Reply #8 on: May 12, 2014, 04:05:07 PM »
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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Re: DC-K40 Laser conversion issue
« Reply #9 on: May 13, 2014, 01:41:12 AM »
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.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.