Newbie- Desktop engraver/cutter

[fantasy2]

There are a lot of treads about choosing a new desktop laser but on non of them I can find a clear answer to my questions.

What I want to do is to cut in sheetmetal like stainless steel or brass with a thickness of +/-0.1~0.5mm. I also want to make cuts in kapton material(like the orange tape on flexible PCB's). I guess kapton is not a problem but the metal could be? Cutting in multiple runs is not a problem for me..

I also would like to engrave on anodized aluminium, from what I heard and read that's not a big issue? And the last thing that I would like to do with the machine is to burn 35µm of copper away from an epoxy PCB to make my own PCB's with the laser, is this possible? I saw some LPKF machines doing that, but they are way too expensive.

I saw that the versalaser could do almost everything but it would costs like 14.000 dollars excl. shipping and VAT to my place. My budget is +/-8000 dollars. I was looking at some chinese ones but they have very few specs on their website and from reading al the posts here I'm not sure if I should believe it.

Anyone here that van make things clear for me? Thanks!

[zax15uk]

Hi, I assume you are looking at an Nd:YAG or high power CO2 laser as these would be suited to the applications you describe. I would suggest a pulsed rather than Q-switched YAG laser.

For making copper boards it may be better to remove a sacrificial layer (resist) and chemical etch - but you could directly remove the copper if desired.

The CYG400 is a 400W Nd:YAG which is suitable, but out of your price. It is going to be difficult to find a suitable machine under $8k, you could try Han's Laser.

Would you consider a CNC for the metal cutting / engraving and a small diode laser for cutting Kapton tape?

Zax.

[fantasy2]

Yes I was looking at Nd:YAG and high power CO2. From the time that I was studying precision mechanics, I know the school had serveral CO2 machines, very small ones for engraving(if I'm correct it was 6Watt CO2). Marble and black anodized aluminium wasn't a problem for that machines although it sometimes had to do several rounds.

We also had another, not that big also and it was able to cut through 0.05, 0.1, 0.2mm of steel. I'm not sure if that one was CO2 of Nd:YAG but it was a small machine.

For the PCB, first getting the light sensitive layer away and then chemically etching the rest sounds good too but I prefer doing it all in one run. The copper layer is only 0.035mm thick so I'm still a bit like, why can I do 5mm plexiglas without a problem but not 0.035mm of copper..

Is there a table or diagram that shows through what thickness you can cut with what size and type of a laser?


Oh and 2 different machines is not really an option, CNC makes a mess and you need cooling and such. The edges are less nice than with a laser.

[zax15uk]

A low power (<100W) CO2 can be used to remove the anodizing layer from aluminium but won't engrave it directly, just as an Nd:YAG won't engrave glass.

It's all about energy absorpsion, different wavelengths will have different effects.

Glass for example transmits 1064nm Nd:YAG and frequency doubled 532nm green laser, but not 10600nm from a CO2 laser. Copper reflects CO2 laser, so even 35 micron thick will be difficult to etch with anything less than 1kW. Acrylic (Plexiglas) cuts and engraves easily with CO2 and can be engraved with Nd:YAG too.

Zax.

[fantasy2]

Is there a comparison table that shows me what kind of laser with how much power I need to cut different materials and what materials is shouldn't use(like PVC)?

For a beginner it's not easy to find out what I can and what I can't with the engravers. For example, I could buy a 80Watt but maybe it was better to buy a 30Watt laser..

Also, if I want to engrave grayscale pictures with the machine on for example, glass or epoxy. Can I change lenses so I have a smaller spot size? Can I also do "3D" cuts to make the grayscale more clearer?


One thing I found out that I find very cool is that it should be possible to engrave pictures on chocolate, would be a perfect gift

[Litografa]

Hello,
First of all it is not reccomended cut PVC on laser. See attachement what can happened with your laser after PVC

Concerning settings - different settings are for different lasers - glass or aluminium tube. Basically - more power - bigger laser dot size, but with lens you can slightly adjust dot size.

I never try engrave on chocolate but I have one customer who engrave on soap

[fantasy2]

wow, did PVC really do that damage to the machine? :|

A 80Watt laser has a bigger spot than a 30Watt laser so with 30Watt you can make sharper pictures, ok, I get that. But are those different lenses available?

Is it possible to change depth while engraving(for a more '3D' picture)? Or for example while cutting balsa, that I can cut pockets?

[Litografa]

First of all my information is 100% valid for lasers with aluminium tube. For chinese lasers with glass tube could be slightly different situation.

Generally speaking there is three lenses - 1" or 1,5" for fine engraving, 2" - universal for engraving and cutting up to 10 mm, and 4" for cutting up to 20 mm.

Possibility engrave 3D files depend from software-hardware combination. With GCC lasers you can do 3D, but of course this is VIRTUAL 3D when you can not achieve exact 3D surface.

[zax15uk]

fantasy2,

I cut some PVC by accident (it was incorrectly marked as laserable engraving stock when it was for rotary machines only). I stopped the laser after only 1 second - when I saw the puff of green smoke, but the result was instant. My table and some screws were immediately rusted. Luckily the exhaust system was ok as most of that is plastic.

You can focus an 80W glass tube laser down to a very small spot size for engraving fine detail, just as you could with a 30W. The problem is ZnSe lenses for CO2 lasers aren't cheap, so once you get above 100W and the spot size increases or as is common you collimate 2 lasers (2x60W for 120W etc) the cost is prohibitve.

As Litografa said, controlling the laser power on the fly for pseudo 3D engraving is possible but requires the correct software/machine combination. You will find some of the smaller machines made for stamp making actually have this capability so they can produce angled side walls. The software is limited though as it is for a very specific purpose.

Depending on what you want to achieve, it is also possible to create layered jobs where you etch more and more on subsequent passes. There are software packages available that can slice a 3D model or photo to create vectors for each pass. Another alternative that almost any laser is capable of doing is using halftones (dither patterns) to create some depth. This is very effective on certain materials.

I haven't tried engraving chocolate, it usually doesn't last long enough around me, but I see no reason it wouldn't work. I have tried candles and they work ok providing you don't want too much detail.

Zax.

[fullspeceng]

To mark metal, you need a LMM; google Thermark.

To cut kapton/mylar, it is no problem. I do it all the time for pcb stencils.

You should get a laser with PWM power control so you can engrave at high or low power easily.

If you are interested, I sell a 50W Co2 Laser that runs Mach3 for $2000:
http://www.fullspectrumengineering.com/co2laser.html

I can cut 1/4" acrylic no problem, 1/4" poplar wood no problem, etc.

Mach3 gives you better control.

[fantasy2]

Wow, the noice from that machine, is that the steppermotors using PWM at low speed?

[zax15uk]

The noise is from the steppers moving at a slow speed, and probably sounds worse because of the sensitive microphone. PWM is for the laser control.

I find Newlydraw to be adequate as a 'driver' for engraving and light cutting, it imports DXF files flawlessly which is more than I can say for some of my high dollar programs (Gerber Omega, ArtCAM etc).

I would definately prefer better speed control as shown in the video, and the ability to adjust power using PWM. The only issue I have is with using Mach3, I would much prefer a PLC solution with USB interface. I wonder if this is possible with the external pulse generator (Smooth Stepper)?

Zax.