Thread: Greolt's Laser Build

Also some vector cutting with Mach3. Coloured acrylic.

Awesome work as usual Greg. Gold star for you.

Hi Greg,

Nice work, congratulations on a successful build.

Any pictures of the completed machine?

Regards
Ray

Ray

There are some pics in posts 47 and 53 of this thread.

Greg

Hi Greg,
Very inspiring work.
A laser in on my list as soon as I have finished 6b4, my solar projects, hybrid mill and ...
Are you pleased with the outcome and would you change anything?

Originally Posted by rodm

Are you pleased with the outcome and would you change anything?

I have not as yet really got into engraving and until then I will reserve my judgement.

So far I am using Mach3 to run it and that means 2D vector cutting is going great, but also means that I am only playing around the edges of engraving potential.

A proper laser controller DSP is needed to really make this thing sing. I will be ordering one soon.

When that is all going and I learn to drive it, then I will start to see if and where I could have done better.

Greg

Hi Greg

Nice build. We are decomissioning more gear at work so that means its time for me to start my next build... pity I don't have any room

I was thinking large format plasma but your build is making me think the laser might be more interesting

I'm confused though as I don't understand why you need a hardware solution over Mach3 to control the machine nor what exactly you mean by a DSP controller for the laser. Is it a speed issue? I know that I get a fair bit of dwell time with the gcode I generate for my router.. probably not so good in a laser setup.


Cheers

Mark

Mark

Mach3 would be fine for 2D or vector cutting.

Combined with a SmoothStepper it is fast enough for any material. Even with the LPT it is fast enough.

Delays turning laser on and off are not a problem. Using M10/M11 commands.

As CNC router users we are very accustomed to going from CAD to CAM to Mach.

Typical laser work flow is, CAD or CorelDraw to a print driver type app where you set a few parameters and off it goes. So laser users see the Mach route as cludgy and complicated.

Then you come to what is for many, a very important function of a laser, which is engraving.

Mach3 has an engraving plugin that was written for impact engraving. It has been adapted to laser engraving and with a lot of trial and error can be made to work quite well.

However engraving jobs often involve some vector cutting and that adds a level of complexity. The engraving being done with the plugin and the vector being done via CAD CAM etc. Origins have to be matched. All this can be done but it adds a lot to the workflow and the number opportunities to stuff up.

Another thing is the axis speed that will work with the plugin is snail pace compared to a laser controller.

A laser can exhibit a very small difference in the laser firing timings between left to right travel, and right to left. This can result in a stepped line. Nothing can be done with this in the engraving plugin. Just have to travel even slower.

In a dedicated controller there are parameters that can be set to eliminate this.

For a router that has a laser as an add-on attachment, Mach would be fine.

For a purpose built laser, like mine, when you compare the two options, it becomes a no brainer.

Greg

thought a lasers use the "old plotter " printer software

just press the print button on any drawing , no cam involved

Yes it is a bit like that, but you need to set power and speed for a given cut or engrave.

You also may want to set the order of which things happen etc. So it is a little more than what you might think of as normal printing.

Another thing with this particular controller is that it does not need to be hooked up to a computer.

You can either operate it from a computer, or transfer the job file via USB drive and do all the machine control via the operator pad.

Greg

Thanks for the clarification Greg . My last job was for a company that makes imagesetters for the printing and circuit board markets so understand the issues that you described. I was thinking more from a vector perspective (cutting) rather than raster (engraving) one... all makes sense now.

You've raised another question though... seeing as we are talking about high power gas tube lasers that don't typically like to be modulated at any great speed what are you using to accomplish this? A galvo mirror or acoustic modulator?

Also does the controller act as a page buffer for the data ie FIFO with the step pulses used as a data clock?

Then again the data rates we were dealing with were a bit higher so maybe I'm over complicating it... ie 24000 rpm multi faceted scanner with 2000 DPI resolution and +- 0.00025"accuracy.

With all the whinging in the media over laser pointers I assumed getting a 80W CO2 laser imported would be a big hassle.

Cheers

Mark

The laser power is controlled via PWM at a fixed frequency. And then the laser is tuned on and off for vector cutting. Pulsed or making dots whilst engraving.

As far as I understand the job is sent to the controller hardware in one go. Then the job runs from that hardware. With possibly pause and stop being sent as required. There is no constant feedback of DRO updates like between a SS and Mach3.

All this is what I have gleaned from the documentation. I will see more when the unit is here and installed.

As far as importing a laser tube, I presume the restrictions are not as severe for a 1200mm long tube to be built into a machine, as they are for hand held laser pointers, which they are very down on.

Also for something like this, the last thing I am going to do is ask authorities for clarification. Everything would then be impossible.

I had no issues and the sellers are sending them to Aus regularly.

Greg

yer i didnt have a problem importing ,cross hair , and IR laser parts ( 1/4 watt )

it the complete units with battery's that are banned ,
if its got a wall mains pug , or is a "part " it's ok

Hi Greg

Most of my experience has been with solid state lasers and at very high modulation rates so very different beasts to high power gas tubes. However the way that I've seen modulation done on high power ones for light shows is using an aperature and galvo mirror (first surface mirror on a tilting solenoid that diverts the path just enough such that the beam misses the aperature) or an acoustic modulator (fancy crystal that also bends the beam but using a RF signal and defraction)

I guess it comes down to how fast you scan and what sort of rise time you need to get from beam on to beam off.

If you do end up using a constant beam with a deflecting element where the beam goes when not aimed at the job needs to be a heat sink... this is a good one. Stack a bunch of razor blades together to form a block (can you still get those ones that Guilette made before disposibles?) as the peaks and valleys form a light trap that sets up distructive interferance.. ideal "black box element" .

So how did you decide on 80W ? I like the look of this video... [ame=http://www.youtube.com/watch?v=e9BvPeAmuvc]150 Watt CO2 Metal Cutting Laser by KERN LASERS - YouTube[/ame]

And is the kind of stuff I would like to cut so maybe I need to ramp it up to 150W

Never have enough power they say