[ccarlsen]

Hello everyone,

I have been toying with the idea of building a personal cnc unit for some time and am considering a laser engraver and cutter as my project. I have done a fair amount of CNC and manual milling and was considering building a 24"x24"x3" xyz motion for side projects, but I would really want to build in a tool changer if I did, and that is a lot more than I have time for right now. I have looked at just buying a k40 to play with, but they are small and lacking in quality. Plus it does not allow me to make my own motion.

Before I get into my questions, I should list the specifications I am looking to build to.

minimum 12"x12" bed size, 24"x24" preferable
able to rasterize images for engraving on acrylic and wood
cut 0.25" acrylic, wood, fabric, 0.0625" tag board
compatible with software capable of importing 2D cad files


So, I have several questions to determine the path I am to take for this build.

What controller/software package to use? I have been looking at the AWC608 from LightObject. This seems to be the most robust and capable unit available, but it is severely lacking in documentation. It would be nice to use a less pricy unit, but I would like it to be compatible with a capable software package.

What motion type to use? I was originally looking into using ball screws, but seeing as the carriage with not be under heavy loads, this is probably unnecessary for this application, but would be nice on the speed/accuracy side of things. Every build I have come across uses stepper motors with belts, which seems good for speed, but I would worry about missed steps, stretched belts, and jiggle in the motion. The dynamic loads are fairly low with these machines, seeing as you only fly optics, but I am a stickler for accuracy. Maybe just an acme thread? What is the nominal traverse speed that you generally aim for.

Laser power? I assume my only option, at least to start with, is using a co2 unit. A minimum of 40 watts would be good, but do I need 60 watts or higher? This should be a function of spot size and traverse speed, but how do I calculate this for different materials? In fact, if anyone knows of some literature that I could read explaining calculations behind depth of focus, spot size, power, and optics, that would be fantastic. For instance, do I need to consider the change in beam length as the motion traverses the cutting area and compensate for this some how?

Thanks,

ccarlsen

[pippin88]

Use belts, screws are too slow / have screw whip at high speeds.

40W is too low to realistically cut 1/4" material. 60W may do it (I've not used a 60W unit)

AWC608 DSP is well regarded. I've written a guide for using LinuxCNC: http://www.cnczone.com/forums/genera..._need_dsp.html
You can always start with LinuxCNC and buy a DSP later if you find it doesn't suit or finances delay things. Buy the right drivers the first time and the only thing you'll not be re-using is a breakout board (I think).

[spclaser]

If you just for cutting work, the screws is a good choice. Although slow, but the effect is good, it has a higher accuracy.But if you also want to do some engraving, the belts is good. As for the controller, leetro controller is very popular. If you purchase a laser cutting machine, you only need to let the professional manufacturer know your demand, They can give you a satisfactory answer.
As a professional manufaturer, I can give you a recommend for your reference Attachment 195296
This laser machine owns the newest design, easy-operation system, 24x18 lnch table size, motorized Z axis lifting table. It use the DSP control system, Laser power is 60W,it can applied to wood and acrylic and fabric. it matched with belts motion system, can both do cutting and engraving.
If you have other questions, I am glad to discussing with you.