Hi all, new BIG laser on its way and I have a few concerns… I’m building a 4’ x 6’ laser with an 18" z bed. I’m beginning to get a little worried that the bigger this thing gets the less efficient LW4 (smoothie) will be. I noticed that with my current setup (12" x 26") jobs begin to get glitchy the bigger they are. For example, a relatively small job will be smooth as silk but if I create a design that’s near the limits of my machine, it begins to have a hard time with round paths. Here’s a video of what I mean attached. This project is roughly 12" x 12" when done. So now the worry becomes, will I even be able to run full capacity jobs? I’d love your guys’ thoughts. Thanks
https://www.dropbox.com/s/pscjizi0jitx7s7/20170814_211648.mp4?dl=0
4x6??? That’s a monster. What are you building?
Well, you might say its a monster and so would I LOL… I came across a large quantity of 8020 extrusions and being tired of cutting my wood to size to fit it my bed, I decided to go all out and build this monster… The construction will consist of 8020 for the main frame and bed. (4) 20 inch lead screws for the bed. (3) nema 23’s with lots of torque. I also bought new drivers to go with them. Everything will run on 15mm linear bearings (also free)… I have new power supplies and ventilation on its way as well. I’m still designing hence asking the question before I build it. I will still need an enclosure to complete the build if I go this route. I need to find out if there are limitations to the hardware (smoothie) and the software (Laserweb). Here’s a mock-up.
Where is this magical place to get stuff for free? Or maybe I can also stumble?
@Chuck_Comito here kind of an answer you need.
http://robotseed.com/index.php?id_category=11&controller=category&id_lang=2
The stuttering seen in the video looks to be Laserweb4/smoothieware serial issue. You can eliminate that by running the gcode from the sdcard using smoothieware player.
I was running into the same issue too but I have moved over to using grbl-lpc firmware instead. On one of my test machines, Laserweb4 will feed gcode over 900mm/sec smoothly (600lines of gcode per second). I am too making a large format laser and testing the software/hardware beforehand to verify capability.
This is the 400x400mm test machine running Laserweb4/grbl-lpc.
Laser will be slightly bigger at about 800x600mm
One problem you may run into is generating Laserweb4 raster gcode for very large high resolution images. Laserweb4 will lock up. You can test this by using a 300dpi image and in-large it to something like 800x800mm and generate a raster gcode.
@Chuck_Comito that is a build I’d love to follow and know everything about ! 
The (dangerous) mention of serial speed challenged made me remember a question for those in the know: When playing back gcode from the sd card on smoothie, will it still feed the coords back to LW4? Can you still pause/stop it from LW4?
I will find out @CescoAiel and let you know when I get a chance to experiment however I’m not sure if this really answers my problem. If the sdcard solves it then that’s great but I really like running from my pc. Is there anything that can be done in config file that might help with the transferring of gcode over USB?
@Chuck_Comito i dont think there is, unless you change the firmare to grbl-lpc but you loose the screen support
@Jim_Fong So to be clear, you’re running GRBL LPC on your smoothie correct? What are the pros and cons you’ve seen so far if you don’t mind me asking? Thanks…
@Chuck_Comito running grbl-lpc on a Cohesion3d Mini (smoothieboard compatible)
The really smooth motion under USB serial is the biggest factor in running grbl-lpc. When running smoothie firmware, I would have to copy the gcode over to the sdcard and then run it via the LCD panel. Well that got old after awhile. Couple of times I selected the wrong file even. I have lots of laser gcode files.
It’s just much easier and less error prone when running directly from Laserweb4 USB serial. I have 4 CNC machines and it’s just what I am used to doing.
As far as laser cut/raster quality, I don’t know if there is much difference between the two. Seems like the laser has more power under grbl but that is a PWM config. I didn’t really experiment to much on changing the default Smoothie PWM parameters. Setting it similar to what grbl default would probably make it same.
The LCDpanel is nice but I don’t miss it at all anymore.
Reliability under grbl. Hasn’t crashed yet but neither did smoothieboard. Any mistakes were end user setups and initial learning curve.
I won’t be going back to smoothieware until USB serial is working to my satisfaction.
@Jim_Fong thanks for that. I will try it out. My LCD isn’t hooked up anyway as I’ve always liked the pc better. I won’t miss it either but it does change the plan for my controller setup. I can always add the LCD later when smoothie is smoother 
No experience with Smoothie firmware but I’ve got a 6.5’ x 8’ table that runs buttery smooth with a controller running grbl. I’m using it to cut material, no raster jobs. Sounds like grbl-lpc is going to be the way to go.
Thanks @Malcolm_Morris-Pence . I was hoping to not buy another controller and just switch my old to the new build but now I’m worried I might end up down for a while if I switch the firmware. Do you have any pictures of your build? I’d love to see it.
@Chuck_Comito , here’s my current setup. Very much a work in progress (along with the messy garage). If you’re worried about downtime in swapping controller firmware, you can always pick up a Chinese grbl controller board for around $20 on the usual sites and I’ve found they work pretty good. I’ll attach a picture of the two I’ve used.
Here are the two controllers. Newer top one was about $20, and I believe the old red one on bottom was $30ish. I stopped using the old one because it had all of the limit switch pin headers tied to one Arduino pin instead of properly broken out for each axis. Also wanted access to the coolant pin for some other features I’m working on right now. The new board on top was a gamble that payed off. Great board with optoisolated connections, the only drawback being it’s not preconfigured for TTL. But since I’m not making use of my laser’s TTL it’s no loss for me anyway. The board’s mosfet-switched 12v output had worked plenty well for modulating power output for my use. Finer quality for raster might be a different story.
@Malcolm_Morris-Pence thats huge. What do you do about ventilation?
@Chuck_Comito Right now there isn’t any real ventilation. I run it in the garage with the door open. I have a small fan mounted below the laser to help keep smoke from obstructing the path of the light. When a couple of other parts are closer to finalized I’ll be adding a shroud for the carriage that will help cut down the amount of UV light thrown off. It’ll also serve as a way to mount a bigger fan which will both cool the laser diode and blow off the smoke.
At this point I’m really not worried much about fumes since it’s used in an open space that gets plenty of air flow and I’m only cutting very light nylon fabric. When the table graduates from my garage to a more permanent indoor location, I’ll probably be looking into a hanging fume extractor solution.