Choosing a laser for a laser cutter

[EpicHam]

Thanks for the insight, guys. I'll probably spring for the 9mm in the next week or so once some more money comes in. I can use that time to search around for the best price (any suggestions?). I can probably have a fan blowing on the surface of what's being cut to try to extinguish any flames.

I'm really looking to use this for cutting paper/cardboard, possibly vinyl stickers if I could find blank sheets, engraving some random items, but possibly most importantly, engraving into PLA plastic of things I 3D print. I'd really like to be able to print some cool, thin things, like gear boxes or whatnot, and then be able to engrave my contact info on the back of it and hand it out as business cards. Hopefully within a year or so when I (hopefully) have more income coming in, I plan on dropping some cash and building the Open Source BuildLog.net 2.X laser with a higher powered CO2 laser, which will be used for more advanced cutting and engravings of acrylic and the like for bigger projects. So this one is just something to keep me going until then, and to wet my palate to build something later with MOAR POWER!

Play safe eh?
And as always.
Have fun

 

[hakzaw1]

Hiya,



That's a Galvo fast because the only thing moving is the mirrors, Likely CO2 but possibly a YAG (Lamp or Diode Pumped Solid State)
Mucho expensive but great bits of kit



Absorption rates of materials in the IR range are pretty good, for acrylic at 1064 the absorption rate is near 100%.



The inverse square law applies to lasers, (mostly due to detritus) double the power doesn't get double the cutting ability or speed, it's a 4/1 ratio normally. Double the power will get you somewhere about 50% extra cutting ability (speed,thickness) Same applies to increased speed, double the speed needs 4x the power to get the same or similar results. (the figures aren't exact but a pretty good benchmark)

best wishes

Dave

ps: Hiya Things

************

Dave..


Great first-ever post-- came here with help to offer--
I think you already know Dan (Things) he is a mod here- you two have cutters in common.
+3 rep for an excellent 1st post even if it was not an intro in the WELCOME section..

nice to have you here..hk

 

[Multimode]

Hi and welcome,

Great salvage operation and you have some of the parts working already.
As previous post have suggested, a 445nm diode of 1.5 to 2W would get you going and will cut paper and engrave thicker materials. Also safer to work with than a invisible CO2 beam.
Be careful of smoke, soot and dust getting on the lens. You might want to consider having the output beam firing down a tube that has a slight positive pressure to keep out the muck?

I'm a big fan of the arduino, but for CNC have you seen Mach3 ?
A free and very capable demo veresion, (full version is low cost) I've used it on a bridgeport milling machine.
Machsupport Forum - Index

Keep up with the good work.

ATB
MM

 

[origamimavin]

Great idea about the positive pressured tube, I hadn't thought of that! I know just how I could do that by tapping into the same fan output blowing across the heatsink.

I haven't heard much about Mach3, other than maybe hearing it mentioned here and there.. what is it exactly? Software? Hardware? If it's software, can it work with my Arduino setup? My only experience is with Ramps 1.4 connected to an Arduino on my 3D printer. I was still going to have to figure out some way, software wise, to send the data to the cutter.

 

[Multimode]

Hi Origami,

Mach3 is a PC based software program.
It uses the LPT port to send the step and direction signals to the stepper motor drivers.
It will synchronise the X & Y (and Z and A) axis to position the workpiece under the tool / laser etc.

It uses standard GCode file and this can be generated by long hand or by designing your shape / pattern in a cad program then say use a DXF to Gcode converter, or even a full blown CAD CAm program.

It will bypass the need for an arduino, but will get you a good (almost industrial capability) control system, and will give you the oportunity to learn industry standard Gcode

If the exercise is to learn Arduino / C programming, then stick with it.

Either way will be awsome learning.:beer:

 

[origamimavin]

Very interesting, good to know! What kind of tech is needed for something like this? That is to say, I assume the LPT will have to connect to something like a stepper controller (like EasyStepper) to apply proper current and voltage to the steppers (and the LPT is just sending steps and direction over 2 wires per axis). Is that correct? I'd also then need some type of USB to LPT dongle or something, if it's available, since none of my computers have that port.

I was hoping to learn Arduino and C through this project, but I'm still at a spot where I can veer off course if there's good reason to. I still have more research to do in finding/ writing the right code that can accept gcode and turn it into movement commands. I saw a couple other similar projects to what I'm doing where they etch a PCB to interface the Arduino and the EasySteppers, and since I've never done that before either, I thought it could be fun to try.

For a hodge-podge project like this, there are a lot of ways to get it running, it's just a matter of knowing how or having the resources to learn how.

 

[Multimode]

I assume the LPT will have to connect to something like a stepper controller (like EasyStepper) to apply proper current and voltage to the steppers (and the LPT is just sending steps and direction over 2 wires per axis). Is that correct?

I'd also then need some type of USB to LPT dongle or something, if it's available, since none of my computers have that port.

I was hoping to learn Arduino and C through this project, but I'm still at a spot where I can veer off course if there's good reason to. I still have more research to do in finding/ writing the right code that can accept gcode and turn it into movement commands. I saw a couple other similar projects to what I'm doing where they etch a PCB to interface the Arduino and the EasySteppers, and since I've never done that before either, I thought it could be fun to try.

For a hodge-podge project like this, there are a lot of ways to get it running, it's just a matter of knowing how or having the resources to learn how.

Hi Origami,

You are correct, I'm assuming the easy steppers use step and direction so these will work with Mach3
I used a break out board which just buffers the LPT port for protection.
I don't think you'll ba able to use a USB to LPT converter as the Mach3 driver will be expecting to see a real LPT port.
However, there is a board called Smooth Stepper which is USB connected, but is $$$.
My Mach 3 runs on an old 1ghz PC...maybe an option to pick up an old PC?

But.... looks like there are lots of arduino Gcode implementations.
this one looks good:beer:
Dank

 

[origamimavin]

Nice find of Dank, giving you +1 for that one

I'll have to look into Mach3 some more, but I'm guessing Arduino would work fine for this project. The LPT connection method seems really nice, but since this is all going in a small apartment and I'm using a small netbook to control everything, adding a desktop into the mix would be a little silly right now. But it's certainly something to think about for future projects!

 

[Multimode]

Nice find of Dank, giving you +1 for that one 'll have to look into Mach3 some more, but I'm guessing Arduino would work fine for this project. The LPT connection method seems really nice, but since this is all going in a small apartment and I'm using a small netbook to control everything, adding a desktop into the mix would be a little silly right now. But it's certainly something to think about for future projects!

I like it when a plan comes together

I think I'll have to add this one to my list of projects - I've always wanted to build a mini CNC milling engraving machine.:beer:

ATB
MM

 

[Spooky]

Tweakie, Tweakie.CNC, CNC, router, mill, engraver, vinyl cutter, laser.

Tweakies site, he does all sorts of stuff with lasers, diodes,tubes and electronics Last time I spoke to him he's designing a control system for a laser diode based cutter/engraver.

Genius doesn't come close to describing the guy

best wishes

Dave

 

[Things]

Yeah, he helped me a bunch when I was trying to get mach3 up and running on my first machine. Eventually gave up and bought a DSP