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laser engraving/cutting help
« on: December 11, 2010, 04:36:33 PM »

What do I need to get in order to control when the laser is on or off and how much power etc - In order to control a laser with Mach3?

Links to what I need to purchase and to descriptions to settings and configuration would be greatly appreciated.

Thanks!

Offline Hood

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Re: laser engraving/cutting help
« Reply #1 on: December 11, 2010, 05:03:59 PM »
Have a look here http://www.machsupport.com/forum/index.php/topic,12444.0.html  , Tweakie has a thread all about his laser setup.
Hood

Offline Tweakie.CNC

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Re: laser engraving/cutting help
« Reply #2 on: December 12, 2010, 08:26:09 AM »
studysession,

What type / model laser do you wish to control ?

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: laser engraving/cutting help
« Reply #3 on: December 12, 2010, 12:23:37 PM »
Something like this for engraving -

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170421422715&ssPageName=STRK:MEWAX:IT

I have never controlled anything except the 3 or 4 axis with Mach. I know you "can" control a spindle which would be a relay switch and stuff - But do not know what I need in order to do that.

Offline Tweakie.CNC

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Re: laser engraving/cutting help
« Reply #4 on: December 13, 2010, 06:06:44 AM »
There is one problem area with diode lasers in so far as they prefer a ‘soft start’ if they are to enjoy their expected lifespan but this would not be practical with CNC usage as it would make everything far too slow. The attached circuit could be used to interface your PC and Mach3 to the diode laser and you could perhaps, initially, use the M3 M5 combination configured to the output pin of your choice to actually turn it on and off but as mentioned earlier you must expect a reduced diode life when using this method.
A reasonable alternative solution would be to use a shutter system for the switching and leave the diode on for the duration of the program. There are some more details of the shutter I have used and diode lasers in general here http://www.cooperman.talktalk.net/files/18.htm .

Hope this helps.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: laser engraving/cutting help
« Reply #5 on: December 13, 2010, 07:30:34 PM »
Thanks!! Will check out the link.
Re: laser engraving/cutting help
« Reply #6 on: December 13, 2010, 07:57:28 PM »
Your site is awesome. great work.

Would you be willing to share the DXF or PDF version of your cube?
http://www.cooperman.talktalk.net/files/12.htm

I have to re-read somethings but I think I understand a lot of what's there. As I re-read, I am sure I will have some questions.
Thanks

Offline Tweakie.CNC

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Re: laser engraving/cutting help
« Reply #7 on: December 14, 2010, 02:06:13 AM »
Quote
Would you be willing to share the DXF or PDF version of your cube?
http://www.cooperman.talktalk.net/files/12.htm

If I can find it, you are more than welcome to the file. It has been a while now since this was done and things just move on.  :D

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: laser engraving/cutting help
« Reply #8 on: December 14, 2010, 03:13:55 AM »
Hi,

Soft starts for diode lasers are really not needed anymore xecpt as power on delay of about 10 seconds to make projectors legal in some countries.
Good laser drivers has a threshold setting that sets a base current for the diode that makes it just turn off so that even a very tiny voltage on the input produces laser output, that makes the diode habby by not "restarting" it every time you want to turn it on-off.
I have drivers and diodes that can be modulated to over 100khz and work that way for years without degradation.

Most ebay diodes are ok but the drives are usually crap, toss the driver and buy a Flexmod P3 from here:
http://hacylon.case.edu/ebay/laser_diode/FlexModP3.php and you will be ok, it can be controlled by TTL (PWM) or analog modulation (0-5V controls output power, scale it to use 0-10V from VFD control voltage from MACH3 with a breakout board or Gecko G540)
The driver has a modulation frequency range from DC to 160kHz so you should be ok, it's about 5khz output freq from most laser controllers.

Lasers that have a pump diode that drives excites crystals to provide the visible alser output can suffer from poor modulation (f. ex green DPSS lasers) but even they do not break just exhibit weird modulation effects of the output power when the frequency is changed abruptly.




There is one problem area with diode lasers in so far as they prefer a ‘soft start’ if they are to enjoy their expected lifespan but this would not be practical with CNC usage as it would make everything far too slow. The attached circuit could be used to interface your PC and Mach3 to the diode laser and you could perhaps, initially, use the M3 M5 combination configured to the output pin of your choice to actually turn it on and off but as mentioned earlier you must expect a reduced diode life when using this method.
A reasonable alternative solution would be to use a shutter system for the switching and leave the diode on for the duration of the program. There are some more details of the shutter I have used and diode lasers in general here http://www.cooperman.talktalk.net/files/18.htm .

Hope this helps.

Tweakie.

Re: laser engraving/cutting help
« Reply #9 on: December 14, 2010, 09:52:40 AM »
Where did you buy your engraving laser from?

And if you can find that file - I would greatly appreciate it.

Thanks!!!