I’m finishing the table base for the LR4 and I’ve been thinking on trying a Laser build instead of a router, mainly cutting plywood and thin MDF with a max width of 10-12mm, it’s a matter of noise reduction.
Here’s the build thread New LR4 Build in Catalunya - #95 by AlexBondCat
I’d like to find a decent laser of 40-100W and would like to know what changes need to be made in terms of board config, etc…and if @vicious1 board will be able to control a laser, etc
Thanks in advance.
Àlex
You can find stacked diode UV lasers in the roughly 40W optical power range, but they won’t have nearly the cutting power of even a 40W optical power CO2 (IR) tube laser.
Cutting 12mm plywood with an LR4 is a stretch with a stacked UV doide laser, may be a stretch too far.
Here’s an example:
Edit: though not around 40W of optical power.
You’d want a looooong focal length lens on such a dioide laser; a way to get rid of lots of smoke; and a good supply of water to put out the inevitable fires.
Cutting thicker than 1/4" plywood is hit or miss with short focal lengths and MDF is a non-starter in my experience.
I’ve only used a 100W Co2, granted it’s at the local makerspace so gets beat on a lot. Max I’ve been able to cut without a silly number of passes and resultant charring is about 5-6mm plywood. 3mm is more comfortable for it.
Cutting thicker ply is exactly why I built the LR. I bet with the chiller / extract running the laser isn’t that much quieter than my LR if any … I guess I really should dig out my sound meter and get some datapoints eh?
IR lasers are way better at cutting plywood in my experience than UV.
That shouldn’t be that hard for a 100W CO2 laser.
Having better air assist would help it a lot. I’m guessing that laser is not running at 100% anymore
Running my laser is WAAAAAAAAAAAAAAAAY quieter than my CNC… enough that I’ll stay sitting next to it have a conversation with the person sitting there… that never happens with the CNC running
@Jonathjon can probably give you a pretty realistic view of what you can and can’t do with plywood and a diode laser on LR
“Not running at 100%” is really an understatement I imagine. It’s the most heavily used tool in the space, and the maintenance volunteers can’t keep up. Probably one or two people cutting things they shouldn’t and getting crud on the optics, too.
It does have air assist, how good it is… pass. Choice of lens seems to make a big difference, apparently? I don’t know much about laser work - I guess my data point is less helpful than I’d hoped. People seem to have cut fairly thick MDF (~10mm) on it with success.
I suspect it’s the extraction making most / nearly all of the noise - I guess you probably have a much fancier setup than what we’ve cobbled together.
I certainly can’t reasonably use it to cut plywood at the thicknesses I generally work at (18mm and up), whether it’s just had a good bit of TLC or not. Then again, I also can’t use my CNC for that either, because I built it wrong, so 
I just have one of these…
AC Infinity CLOUDLINE PRO S6,… Amazon.com
I 3D printed an adapter and run long 6” flex duct out the door of my garage when I use it.
I just have the stock air assist, but intend to upgrade at some point.
I have a 90W CO2, and was able to cut 1/2" plywood at a reasonable speed with 2 passes and not too bad charring considering the air assist is crap (if I remember correctly)
I didn’t read the build thread, but this seems like a much more solvable problem to get the CNC working correctly than trying to get a Diode to cut 3/4" plywood is…
Common story. At the big local makerspace, I was at one point a shop captain for rapid prototyping, which included the CO2 laser cutter and the 3D printers. No amount of constant maintenance would keep up with the abuse we had- even after adding RFID restricted access and pulling certs for people who misused the machine.
Speaking of extraction- you need a plan for this. One of the major issues with large format laser cutting is all of the smoke and fumes you WILL create. NASTY stuff- plywood glues are not the worst things you could make, but you DO NOT want to breathe their smoke.
Well, let’s sort out how to fix your CNC. This community happens to be good at making CNC routers 
Understandable, there’s a lot of words, I’m afraid it’s my default and only setting.
Yep, we’re RFID locked too, and still not able to keep up. One bad apple…
Seconded, and for anyone playing along at home, the worse things are chlorine gas. Bad for your laser, worse for you. Don’t cut PVC.
Yes please. Otherwise I’ll have to go liberate Ghostrider from @Tokoloshe, whether his new machine is arrived or not… 
This community definitely is good at making CNC machines. I’m not good at making anything, but perhaps with the right prodding…
I wish I’d started the build thread earlier (and that I’d just bought the damn hardware kit!) - I feel quite guilty about gatecrashing the party asking for help with problems of my own making. Hindsight…
On that note, I’d better stop derailing this thread (another of my default settings, apologies) with my apologies to the original poster!
Just haven’t been around as much, and way too far behind to catch up on everything that’s happened…
lol… I didn’t realize it wasn’t you either…
Something is seriously wrong with your CO2 laser machine. A 100W CO2 laser should blast through 5-6mm plywood and should outperform all diode laser machines. I use a 12W diode laser, and routinely cut 5.4mm plywood.
A 40W diode laser should be able to cut 12mm plywood. You will see YouTube tests of these lasers cutting 12mm and thicker material, but 12mm is probably the outer limit for good cutting.
Also be careful of advertised power of laser modules. Ads are misleading and sometimes contain outright lies. There are few true 40W diode laser modules that can be used on a Lowrider, and expect to pay $600 or more. If the price is lower, you are probably getting scammed. Laser Tree is the only brand of 40W module I’ve seen on the forum successfully used on an MPCNC.
Yes. Largely people cutting things they shouldn’t and the wrong ratio of maintenance time to usage. It’s the nature of the beast. Even below its potential capability it does enough to be interesting and useful to lots of people, myself included.
For me CNC routing is way more interesting, and definitely more suitable for my own “shop”. YMMV.
That seems like a crazy ratio of power to performance to me 
That seems like a crazy ratio of power to performance to me
Yes and no. I cut 5.4mm the plywood in two passes at 2.5mm to 3.0mm per second (150mm to 180mm per minute). Big jobs can take a long time, but the quality of the cuts is high (IMO). My point is that, when cutting materials 6mm or less, the main difference between a 12W ($170) and a 40W ($600) diode laser module is the time required to execute the job. If I want thicker plywood, I just cut things twice and glue the pieces. A bit of a pain, but workable.
For laser engraving on the Lowrider, power is even less important since your limits will be defined by the CNC more than the power of the module. The Lowrider is moving a lot more mass than dedicated laser cutters/engravers, so at higher speeds and/or accelerations, you will see artifacts that detract from the engraving.
Haven’t had much time to progress on the LR4 built, work load, but by your answers I think I’ll stick to CNC routing on this built.
Any ideas on what to built for laser cutting?
Thanks.
The questions you need to ask yourself are 1) how big will my projects be, and 2) how much engraving will I be doing? If you will primarily be doing cutting then any machine will work well including your LR4. The speed of cutting will be limited to the power of the laser module. If you are focusing on engraving, then the mass of the machine plays a big part in how fast you can engrave. For engraving, you’d be better off buying a machine rather than building.
For example, back when I was engraving white tiles, this topic about $79 laser engravers came across the forum and I bought one. I replaced the cheap laser head that came with the machine with my NEJE 40640. The time to engrave a 4" by 4" tile corner to corner went from around 80 minutes on my primo down to around 55 minutes on the $79 machine. If I tried to engrave faster on my Primo, artifacts would ruin the engraving.
The $79 machine was a limited-time deal, but there are cheap (new and used) laser engravers out there. The $79 machine has a small working area, but, because engraving takes so much time, I rarely try and engrave anything larger than a 4" x 4" tile. I can still use my Primo for larger laser cutting projects.
Thanks for your reply @robertbu, on the LR4 I intend to cut as big as 1300x650 mm wood projects mainly.
And I’d like to have a smaller machine capable of laser cutting small and thinner wood projects as big as 700x400mm.
The idea of a laser cutter was to reduce as much as possible cutting noise as my machines will be seating in the terrace of and apartment with neighbours, hence why I want to go as quiet as possible.
Any tips on what sort of machine I should go for in terms of laser cutting?
Thanks,
Àlex