New Laser Cutter - Need Advice

[webgeek]

Hi all; I'm in the process of designing and building my own laser cutter. It's inspired by the BuildLog.net laser cutter but has some key differences. The laser will have a cutting area of 4' x 2' and will be 80 watts. It's a gantry-mounted tube system like the Kern lasers. I'm also using the DSP system from Light Object so I'll be able to go the whole "print from Corel Draw to cut on the laser" route. If you want to see my build log and all my current ideas, it's available here:
buildlog.net • View topic - Mike's EyeZap Laser Cutter

I have about a million projects I want to use it on and they range from very small (inches) to very large (multiple feet, full plywood sheets). I plan on vector cutting wood, paper, plastic, etc. I do want to support engraving though that will be far less common than cutting.

My practical experience with laser cutters is a bit limited. I've used a nice but small-ish Universal Laser multiple times but that's about it. What I'm really hoping to get out of this post is specific advice on features and requirements for my machine based the experience you experts have here.

So with all that said, if you were buying a machine to do some of these things, what would you expect it to have from a feature-standpoint? And those of you that have used larger bed machines, what features did you wish it had to make your life easier?

Thanks much!

-Mike

[Rodney Gold]

Go higher in wattage if you going to do a lot of not so terribly intricate cutting , 130-150w is good.

[webgeek]

So that brings up a question I've never quite had answered. Can't I just reduce the power level to get intricate cuts with a higher power laser? I'm already using a long focal length lens to get a tiny focus point. Optically, I could split the beam to reduce power as well, correct?

Also, is there somewhere/something that lists what I can cut at 150 watts that I couldn't do at 80? I've seen from 80 to 100 I get almost no advantages so I was wondering where that changes. Thanks!

-Mike

[Asynchronism]

Here are some of my thoughts, having used a bunch of those machines.

The tubes you're going to buy for the DIY stuff are probably glass tubes, which behave differently than the tubes Universal uses. Rodney is correct... high wattage gives you gobs of cutting power, but you'll have a hard time turning it down for engraving.

Laser cutting is a factor of speed and power. I can cut 1/2" or greater on my ULS 50 watt machine, but it's slow... and eventually slows down to the point where you're just setting stuff on fire. Stronger laser is going to cut the same, but with more power you can move the head faster... or cut a lot thicker at the minimum speeds. I have a thread here about the 150 watt machine I just ordered... I really need something that can cut 3/16 and 1/4 material as fast as possible.

Going from 80 to 100 or 150... really nothing more than cut thicker material more easily, or thinner stuff faster. My buddy's 130 watt sort of marks on metal, but not well. The bigger ones seem to eat up optics faster.

I think ULS or Epilog has a chart on their sites... there are several out there. Synrad has a JS based web tool that shows you as well.

Features? Rock solid drive train is #1. Smooth, no slop, and quick. Some sort of motorized bed would be #2... and you'll want honeycomb. Check out a company called Texas Almet - I just got 2 4x8 sheets of 1/2" honeycomb there for $200. You'll want some sort of red dot pointer, in line with the beam, to try to position some projects.

And I'd probably tell you get a good controller, like the ones from Full Spectrum or Light Object (looks like you picked the Light Object one!)... they're both supposed to have decent software driving them. My machine is coming with a Leetro and LaserCut... if that sucks, I'll be swapping mine out with one of those.

The other thing I'd say is make it easy to service, especially after a fire. Fire is one of those "when, not if" things.

Good luck! - Dave

[webgeek]

The tubes you're going to buy for the DIY stuff are probably glass tubes, which behave differently than the tubes Universal uses. Rodney is correct... high wattage gives you gobs of cutting power, but you'll have a hard time turning it down for engraving.

Looks like the biggest I can easily fit is a RECI 100w. Hopefully that's a good compromise on cutting power and flexibility.

Features? Rock solid drive train is #1. Smooth, no slop, and quick.

Heh, that's big on my list too. I'm using linear rails which are major overkill for this application but they work great and will give me years of perfect movement.

Some sort of motorized bed would be #2

This one is interesting - due to the size of the laser bed, I was planning on using a "pinned" bed system so I can raise and lower the bed accurately. I was then going to have the final focusing mirror be position-able +-1" or so to give me final focus. This was going to be combined with a little focus touch-off-tool so I can find focus super fast. Is the motorized bed that critical? I guess I can't see myself switching material thickness frequently enough for it to be a problem.

and you'll want honeycomb

Interesting. Most of the cutter DIY people are using aluminum lighting grids. Is the honeycomb superior to that considering it's >4x the price?

The other thing I'd say is make it easy to service, especially after a fire. Fire is one of those "when, not if" things.

Good to know - I've designed it with easily removable panels but I'll take extra care to ensure everything is serviceable.

Thanks much for the advice!

-Mike

[Asynchronism]

Hey Mike,

100w should be a good range... and that's still a lot of laser. What material did you want to cut primarily? When you're shopping for tubes, look for Reci... we've gone through a bunch of glass tubes, and noting is nearly as nice. Some US companies resell them, but they're generally far cheaper to just import yourself. Get two!

Interesting setup with the bed, but it should probably work well. The more depth you can build in the better... you'll find all sorts of things you want to engrave on as you go! Engraved wine bottles make great last minute gifts.

The honeycomb... depends on how thick the slats are on the aluminum light grid... I can't say that I know exactly what it looks like. The honeycomb material is what ULS/Epilog/etc use for their beds... it's a very fine wall, so it minimizes the bounce back from the laser.

With light grid material, I can tell you this... avoid the styrene based stuff at all costs... the kind sold at Lowes and Home Depot. I've seen it in white, black and coated to look like metal... all of it is insanely flammable. You can special order boxes of acrylic based light grid - we use that for some cutting projects to get the material up off the honeycomb. It's far less volatile.

I bought a couple of sheets of honeycomb because we periodically replace it in our cutting table, and ULS charges about $45 for a small section. A friend was ordering some thicker stuff, so I went ahead and got a big piece for myself.

Dave

[Rodney Gold]

You can turn down the power to about 15% of the total , so if for EG you wanted to cut paper , you might not be able to increase speed enough to do so without using too much power. Uberthin stuff and very fine engraving might be a problem with 150w tubes
Thick stuff = a long focal point lens , the beam acts like an X and not || (like an hourglass , the waist of the hourglass is where the laser has enough energy concentrated on a small enough spot to cut , as the hourglass thickens about the waist , the energy gets spread over a much larger spot and the laser wont cut but will burn the material) , so a longer lens makes the X act more like || or extends the "waist" of the hourglass . BUT a longer lens has a much bigger spot (wider waist) , IE your cuts will have wider kerfs.

I would be real hesitant to DIY this , you can actually get a fully functional working machine from china for the same or less than you might spend , especially if you consider time you will take sorting out all sorts of issues.
A 1200 x 800 machine , with a RECI 80w tube , + enough spares to build another complete machine (tubes , lenses ,motherboards, steppers , mirrors, bearings etc etc) comes in at about $5k + shipping, albeit you might think you can save $2.5k on this if you just buy 2 tubes + control software/hardware , it might not be worthwhile.

[webgeek]

What material did you want to cut primarily?

Wood and acrylic mostly. The tube I'm planning on using is a Reci as it fits the machine better.

With light grid material, I can tell you this... avoid the styrene based stuff at all costs...

Yeah, this stuff is real aluminum though I'm sure the wall is a bit thicker than honeycomb.

I would be real hesitant to DIY this , you can actually get a fully functional working machine from china for the same or less than you might spend , especially if you consider time you will take sorting out all sorts of issues. A 1200 x 800 machine , with a RECI 80w tube , + enough spares to build another complete machine (tubes , lenses ,motherboards, steppers , mirrors, bearings etc etc) comes in at about $5k + shipping, albeit you might think you can save $2.5k on this if you just buy 2 tubes + control software/hardware , it might not be worthwhile.

I'm sure if I take my time into account it would be cheaper to buy a machine. With that said, DIY laser cutters are pretty common - buildlog.net is one good example of a popular design that many dozens of people have followed. The Lasersaur project is another solid one. All told, this project will cost me about $3600 or so and will be using significantly higher quality electronics and mechanics than a comparable Chinese import laser. It will be using a Light Object DSP, linear rails for motion, high-quality optics mounts and optics, etc. Additionally all of the frame is 8020 aluminum extrusion with CNC machined frame parts. This makes it far more rigid and reliable than anything in the same price range.

Thanks all for the feedback and info everyone!

-Mike

[Rodney Gold]

I view a laser as a tool , it must produce from word go so wouldn't want to spend my time trying to reinvent the wheel , but by all means go for it
IMO, you wont save money or get a substantially better machine than buying one. You will learn and obviously have pride in completing the build and so forth.

My shenui uses a steel chassis and pretty good motion system , its rigid , however rigidity is not that important when it comes to lasering
It also came with gold plated surface mirrors and imported ZnSE lenses , the control board is the latest RDLC320 ( you can find the manual of the card in this post http://www.cnczone.com/forums/laser_...t_mpc6515.html if you want to compare it to the lightobject board) It uses laserworks v5.x software which is pretty good. It's as good as any western machine in function and a lot cheaper and easier to fix.

Total cost of a 1200 x 800 with 2 80w reci tubes (1 intalled , the other spare) , 2extra laser power supplys , knife edge and honeycomb table , spare motherboard , spare lcd panel , 2 spare steppers , 2 spare stepper drivers , 12 lenses , 6 mirrors , exhaust fan , freon based chiller , pipes , 3 spare mirror mounts (which are excellently constructed) ,spare firing head, and all sorts of other stuff was $4800 + shipping.
I have 6 mainstream lasers + multiple CnC mills/overhead routers and engravers and looking at my chinese machine , there is really nothing to modify to make it any better than my expensive "western" lasers , they do the same job albeit a few of my other lasers can travel at a faster speed when scan engraving , which is of no use when cutting thick stuff.
BTW , the chinese supply steel honeycomb , which is less fragile than the ally stuff , works just as well , is easier to clean but very importantly , allows you to use magnets for holding down thin or slightly warped stuff.

Good luck wth your project , whichever way you go.

[webgeek]

I view a laser as a tool , it must produce from word go so wouldn't want to spend my time trying to reinvent the wheel

You and I are actually in complete agreement on this - it is a tool and I expect it to work consistently every time. The difference is I'm quite a bit more skeptical about the quality of any given piece of inexpensive Chinese industrial equipment - some are great, and some are crap. The inconsistency is very scary and means you can get a lemon just as quickly as you get a gem. The number of posts on CNC Zone about how to get "off-the-shelf" Chinese machinery working as you'd expect is pretty staggering and also quite telling in my opinion. For reference, I purchased the largest Chinese CNC milling machine I could afford two years ago - cost about $10k for just the raw machine, this was after already having a smaller Chinese mill I converted to CNC (cost about $2k for that one). Those two purchases have taught me a great deal about Chinese import equipment. My experience with Chinese equipment of this sort is pretty simple: it works great for the cost, but heaven help you if something goes wrong. Something breaks in shipping - good luck getting them to cover it. Something fails out of warranty - let's hope you've got spares. Generally, if it seems cheap - it usually is. I'm not saying you don't get a lot for your money but that every corner that could be cut has been cut and that might come back and bite you. Ultimately, I'm building this machine mostly because then I'll have complete confidence in what went into it. I don't think I could get that same confidence for anywhere near the price of the machines we are talking about.

-Mike

[Rodney Gold]

Read my threads here
Despatches from China
and
Chinese lasers - they're here !!!!!!

[robind]

I am looking for settings for cutting and etching on wood, glass, and the like. I have an Amada 2000 watt laser. We currently cut and etch most metals. We can cut mild steel up to 1/2" thick.