[CJL5585]

1) What is the frequency of the pulse modulated output signal of Mach 3? This signal according to the posted documentation will have to be a frequency of 20 Khz to 50 Khz in order to modulate the laser correctly. I don't use Mach, so I am not familiar with this Mach parameter.
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This is how I personally would hook up the system using a breakout board:

Pin 1 -- NO CONNECTION.

Pin 2 -- Use Output from Mach for "Spindle On" -- Set output to be Active low in software. The G code for spindle on and off will enable/disable the laser.

Pin 3 -- I personally would wire a Normally Closed Emergency Stop Switch between Pin 3 and Pin 4. Pressing (Opening) E-Stop would cut off laser beam in the event of an emergency.

Pin 4 -- Goes to Ground Pin (18 thru 25) on the breakout board, and Pin 3. This is required in order to have the same ground reference for the laser control box and the parallel output port. Otherwise, the breakout board signals will not be able to change the state of any input on the control box, and you will not have an operational modulation signal.

Pin 5 -- Pulse modulation signal 20Khz to 50 Khz to control laser output. (I have reservations that the modulation signal cannot attain these frequencies).

Pin 6 -- NO CONNECTION

Jerry

[CJL5585]

What breakout board are you using?

Does it require external 5 Volt DC power?

If it does require external power, it can be obtained from pin 6 on the control box as another member suggested.

Jerry

[WilliamD]

My breakout board does require 5V, but I am already supplying it. I just read the posts, and THANKS for the input. I will be trying those ideas and reporting back very shortly!

[WilliamD]

It worked! Thank you all! You guys really pulled through for me. I'm going to pull an all nighter to get it done. But I only anticipate another hour or two of work. Then there will be plenty of pictures and what not! I can't believe how well this thing cuts acrylic. I think I'm going to make a custom CNC control panel first. Then put some neon lights behind it. J/K. Although, I know quite a few people who will want custom computer case panels. I have to pay for this thing somehow! But, thanks again!

[miljnor]

who was your supplier for the laser tube/power supply and how much did you pay?

[Mat-C]

I'd like to know where it came from too, as it is working so well

[CJL5585]

It worked!

You had doubts??

Jerry

[zoltan]

Hi,

What was the price for laser tube and power supply and from where have you bought them?

Thank you.

Zoltan

[WilliamD]

No, not doubts. Just excitment! I bought the laser and power supply from a ebay dealer. PKunlimited I believe. Very helpful people to work with. I got the 40 watt tube, matching power supply and half inch GaAs lens for $1300. That was with shipping. But they said since I'm in Phoenix, it had been the cheapest they'd ever seen. The laser tube was overnighted and I got it the next day. They said the liklihood of survival was much better that way. Everything else arrived ground the day after. Overall, very please with the price, product and service. The power supply also came with the HV wire, and a little 12vDC pump to get started. You might as well throw the pump away though. I have a 300 GPH pump I'm trying to use, but I think it will create too much pressure. Any ideas on how to alleviate some of the pressure?

[Mat-C]

Nice....
Don't quite understand about the pumps though, is this for water cooling?

Don't know what pressure you want, but easy enough to regulate it I would think? You can buy off the shelf pressure regs I'd think, or make one (idea that springs to mind is to use a ball bearing sprung against a hole... above the required pressure the ball moves out slightly and fluid escapes). Or perhaps monitor the pressure and turn the pump off if too high?

Another way to do water cooling is to fill a header tank, and use the low pressure from that to go through the laser. Very little chance of breakage through wrong pressures that way. You won't need very much flow to get rid of even large amount of heat energy (eg 0.1 litre / second = about 2 degrees C per kilowatt)

[CJL5585]

Just wondering about the status of the project.

Jerry

[WilliamD]

Sorry for the delay, little more complicated for alignment! Well, I'll have to take pictures later, but this past weekend I welded up a table out of 1.5" tube stock for it. The wood table was just too instable. Then, I realized that I wouldn't be able to just point the laser at the mirror and it would always reflect down. The laser has to be perfectly parallel with the axis I'm shooting it down. So I went to Harbor freight and bought a cheap laser line level. I took the laser out and it was a perfect size. I'll have pictures of that too. But I had made my mirror mounting block and lens holder out of MDF with my CNC router, but a misdirected CO2 beam burned the lens holder up. I modeled a new lens holder in SW, and will post it also. I'm going to have it encased, with pressureized air flowing into it. I've already ruined one lens because of smoke. I also came up with these adjusting screws for the laser, which will help to fine tune the alignment. I had to order a flood coolant setup for the mill, because I'll be making all this stuff out of steel. So I'll be working on it this week, and hope to be done by this weekend. As far as the pump, I just hooked it up to my shower nozzle, and out the drain. Seems to work just fine. I also bought two more lenses. I hear if I put them back to back, the first one will exand the beam, and then next will focus it. I guess the more you fill the focusing lens, the tigher and cleaner the spot. I know Epilog does something like that, but I'm not sure how far they have to be from each other. I'll have some good picutres through the week, and hopefully a happy ending this Saturday! Thanks again for all the support!

[Mat-C]

I figured alignment would be a sod :\
Lenses: The problem with expanding and then focusing is that the beam is then converging at a steep angle, and you get a larger angle on the sides of whatever you're trying to cut. Might work better the other way... converge the beam a little then make it parallel again. I think you want two lenses with the same focal length, and their focal length is the distance apart you want them. Someone else will have to take over from here as I don't know the details.
One further issue: a lot of materials have a different focal length depending on the wavelength of the incident light, so you can't mock it up with red and then switch to IR. Try and get visible and IR lenses and swap when it works with red light?

[WilliamD]

That just went way over my head!?

[Mat-C]

This should help... ie you want something like the diag on the right, so you get a parallel kerf.
Can someone who has actually tried this explain if it is right or wrong?

[WilliamD]

Ahhh! I understand a little more now. I would certainly want something like on the right side. I'm not sure if I'll even go with two lenses yet. Having only one seems to to a great job as far as power, but I will eventually have two going.

[Mat-C]

Here's a real treat for you... just found this:
http://webphysics.davidson.edu/Cours...ics/lenses.htm

Usage is a little unclear, here is what I have found:
Create a lens by clicking lens, then clicking in the main view.
Create a beam on the left in the same way
Drag the lens to move it left and right.
When a lens is selected, you can click-drag its focal point (the little white dots that appear when it is selected).
Screenshot attached

[Mat-C]

PS... a three lens solution will be easier as you can do most of the focusing with two initial fixed lenses, then a less critical one for fine tuning of the beam parallelism.
I used these lenses and positions in the app
x=0.69 fl=1.95
x=2.51 fl=0.14
x=3.6 fl=0.24
As you can see, the final lens is easier to adjust than in the 2 lens solution.
Can someone who has actually done this weigh in with some practical tips?

[miljnor]

well just for starters I would find out what is available on Focal lengths before comming up with some odd numbers that have to be custom made.

The most common cheaply obtainable FL that I have found are 2.5", 1" and .5" but do a search first.

[WilliamD]

OK, time for an update. Well, I've had SUCCESS! Photobucket seems to be having problems right now, so hopefully the photos will be up in a couple of hours.

It's been a real pain, but mostly my own fault. Based on the design limitations, I couldn't accurately couple a red laser beam to the laser, for alighment. I could get it close, but the rest was trial and error. This resulted in one burnt up lens! But lesson learned.

I have some video also, but I know I'll have to find some way to compress it for viewing. Probably host it at YouTube or something. It's incredible watching the little white dot go around and cut. Definetly have to play a lot with the feeds and speeds depending on materials. I haven't even gone to 100% power yet.

I cut most stuff at 50%, and just make two passes. The smoke with MDF is practically unbearable! I definetly have to setup some sort of filter system. I'm actually holding off cutting more stuff because it gives me headaches, makes my eye's water, and I have a pregnant wife! So if anyone knows where to get some sort of carbon filter, I could build a case with a heavy duty blower, and hopefully keep it under control.

The detail the laser is capable of is amazing. I don't even have any designs to test it's current limits. So I'm definetly pleased with the performance! The power seemed pretty consistent for the hour I ran it. I have the water flowing pretty well, and should have no problem keeping it at 70F the entire time. The repeatability is excellent also. I can easily make multiple passes and not even a note of difference in product. This will make my business flow much much faster!