Author Topic: The Laser Project.  (Read 793355 times)

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Offline texaspyro

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Re: The Laser Project.
« Reply #850 on: June 03, 2014, 12:58:09 PM »
Hi texaspyro, I'm very impressed by your results. Can I ask you how you managed to get such a tight focus? Also, would you recommend your setup to cut ~mm sized features in kapton?

The laser that I used is a 405 nm single mode laser.  Single mode lasers can be focused to very small sizes and their beam is much less rectangular than the typical laser diode beam.   I focused the beam manually by eye (use proper goggles) and then tweaked the beam by rasing and lowering the laser head on the mill.  (One way is to place the material on a sloped angle and draw a line on some easily marked material like Kapton.  Then examine the mark with a magnifier and see where the mark is thinnest).   But the location that I came up with was pretty much the same as the manual focus point I came up with.  I can't see much focus diffeence over a +/- 0.25" change in laser height.

I can cut Kapton,  but not very well.   It chars and the char seems to block the beam.  Using enough power to cut the material limits the feature size and quaility of the cuts.

Also,  after I bought my 700 mW laser (which I run at 500 mW max),  a new 1+ watt laser is now availabe.  I have not tried it yet...

Offline balerion

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Re: The Laser Project.
« Reply #851 on: June 04, 2014, 04:01:53 AM »
Thank you very much for sharing. Is it against forum rules to ask for your laser source?

Offline texaspyro

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Re: The Laser Project.
« Reply #852 on: June 04, 2014, 11:37:21 AM »
Thank you very much for sharing. Is it against forum rules to ask for your laser source?
DTR laser shop...  google will find it.  My .5 watt laser is from a 12X Blue ray writer.  The new 1 watt is from a 16X blue-ray writer.  I also built a 3 watt 445 nm head.  It has a beam around 5 mils wide.  I run it around 2.5 watts max.  He has a new 5 watt diode,  but the beam is even bigger.

Those G2 lenses produce the highest output power from these lasers.  There are some 3 element lenses that can produce a smaller beam from the 445 nm lasers,  but they seem to do it by clipping off then ends of the rectangular beam.  You lose around 30% of your power with the 3 element lenses.

My laser driver is a Flexmod P3 from Illumination Supply.  I power the lasers with a 9 volt regulated 3 amp wall-wart type power supply from Ebay.

Oh,  and don't forget you MUST use proper laser safety goggles!!!!!!  Mine are made by Eagle Pair...  DTR has a link on his web site.
« Last Edit: June 04, 2014, 11:39:58 AM by texaspyro »

Offline balerion

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Re: The Laser Project.
« Reply #853 on: June 04, 2014, 11:46:30 AM »
Thanks! I will use my lab's goggles, don't worry  ;)

Offline texaspyro

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Re: The Laser Project.
« Reply #854 on: June 04, 2014, 03:37:12 PM »
Thanks! I will use my lab's goggles, don't worry  ;)

Make SURE that they block the wavelength of your lasers...  not all goggles work at all wavelengths...

Offline balerion

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Re: The Laser Project.
« Reply #855 on: June 04, 2014, 04:34:18 PM »
Quote
Make SURE that they block the wavelength of your lasers...  not all goggles work at all wavelengths..
Thorlabs LG10, 190 to 534 nm, OD = 7+, they should be fine. We are all very scared by our laser (not the 405nm one), hence the expensive goggles.
« Last Edit: June 04, 2014, 04:45:43 PM by balerion »

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #856 on: June 26, 2014, 06:04:05 AM »
Something I keep getting asked about is CO2 laser output power control by using the Mach3 generated PWM signal and the S********* command in the GCode program. This is not something I prefer to do as I always treat engraving and cutting toolpaths as two different operations separated by a tool change. However, PWM control had to be done.

Well, pre-set laser output power is not a constant – it will vary dependant on tube temperature and it’s cutting / engraving ability will also vary dependant on ambient temperature as well as the type of material and it’s moisture content etc. etc. As a result a GCode program with a defined power setting may run just fine today but may need some adjustment to run just as well tomorrow.

There is always more than one way to accomplish anything but this is the best solution I have come up with so far. It does however need a bit of extra hardware to function but this is simple enough to make and just fits inline with the LPT cable to the machine.
The maximum laser power is still manually set and the GCode S********* command controls the actual laser output power between (approx.) 0% to 100% of the maximum that has been set. This allows for the laser output power variations, mentioned above, to be compensated for and adjusted on a day-to-day basis without having to make any changes to the GCode program.

This method basically gates together the Mach3 PWM signal with the M11P1 / M10P1 command codes on Output# 1 just by using a pair of opto-couplers and the LED series resistor values have been chosen to present a loading on the LPT port of no more than 5mA per pin which is well within it’s capability.
This method negates the set-up time delay associated with switching the PWM signal with the M3 / M5 commands by leaving the Mach3 PWM signal constantly running then just applying it as required with the M11P1 / M10P1 commands. Provided any changes to the laser output power are commanded by entering the S********* command on a separate line in the GCode no delays in changing power levels have been noticed and engraving / cutting within the same program is easily accomplished.

The circuit is extremely basic and can be easily made and fitted to an existing machine (which is controlled by the LPT port, of course) and the following pics. Show just what I have done.

(It should be noted that the Vcc required for the opto-transistor is provided by the pull-up resistor included within the laser PSU’s TTL(L) input. If this is not available then a 10k pull-up resistor to +5 Volts may need to be added).

My Mach3 set-up is as follows (please note - your pin numbers may be different).

PWM base frequency 500
Minimum PWM 0
Relay – M3 Output #2
Spin up / down delays all 0
Spindle √  17  0  X  X  1  1
Output #1  √  1  16  X

Spindle pulley 1 Min speed 0  Max speed 100 Ratio 1

The GCode program uses M3 followed by S********* (0 to 100) which is essentially percentage of full power. Thereafter changing power by entering a new S********* command and the laser is switched on / off by the M11P1 / M10 P1 commands. The program then has M5 at the end.

Nice little project for a rainy day perhaps ?

Tweakie.


« Last Edit: July 05, 2017, 02:09:47 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #857 on: July 07, 2014, 06:07:01 AM »
Some further thoughts on this…

By changing the active state of Output #1 to ‘active low’ the circuit can be simplified as shown below.

Tweakie.

« Last Edit: July 08, 2014, 01:55:09 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline wdwkr53

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Re: The Laser Project.
« Reply #858 on: July 17, 2014, 11:12:00 PM »
I followed this thread & was able to get my laser mounted on my CNC spindle to work.  Thanks so much for all the information.  I use Aspire to generate vector gcode for Mach3.  I have to manually insert the E1P0/E1P1 where appropriate for shutting off the laser.  Works great, but labor-intensive in the edit gcode mode.  Is there a plug in or way of "find-and-add" the commands faster?  I downloaded the Impact Engraving plug in, but I would like to do vectors.  Any suggestions would be appreciated.

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #859 on: July 18, 2014, 01:20:48 AM »
Nice work wdwkr53.

Locate your Vectric post processor ( C / Documents & Settings / All Users / Application Data / Vectric / Aspire / ... ) and modify it to insert the M11P1 / M10P1 commands as appropriate. I have attached a typical example of one of the pp's that I use if it's any help.

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