Author: Santiago Ricoy
Email: [email protected]
Date: Last modified on 2/4/17
Keywords: laser cutter engraving etching burning cutting vector raster
The photo above depicts our lab's laser cutter engraving a logo in raster mode (can't tell easily, as it's moving). This tutorial's main focus is to have a student with near zero prior knowledge, up and running a raster engrave on our laser cutter. Other items will be lightly touched on, including vector cuts. The importance of this lies in having a quick-reference for lab members to quickly learn to use and innovate with the laser cutter.
This tutorial's motivation is to teach a student new to the laser cutter how to prepare, check, and run the machine. The tutorial assumes the reader has the following background:
* Know how to manipulate bitmap images
* Perhaps also know how to work with vectorized images in Inkscape, Illustrator, or another related program
* Possible additional background needed in vectorizing and layering in image manipulation programs, and CAD software.
* This tutorial may also attract readers who intend to use the laser cutter to create layers for 3 dimensional projects.
The rest of this tutorial is presented as follows; all students must understand the warnings section:
To complete this tutorial, you'll need the following items:
|PART NAME/DESCRIPTION||VENDOR||VENDOR Number or URL||PRICE||QTY|
|Full Spectrum Laser Pro 36×24||Full Spectrum Laser||http://fslaser.com/||~$14,000 with options||1|
PLEASE READ THOROUGHLY
All above may be obvious; however, knowing what materials should not be cut is very important:
|PVC (Poly Vinyl Chloride)/vinyl/pleather/artificial leather||Produces chlorine gas.||DON'T EVER cut this material as it WILL immediately ruin the optics (HCl likes to eat silvering off of mirrors), cause the metal of the machine to corrode, and ruin the motion control system. Research says that lasers don't BURN materials, but normally VAPORIZE them, leading to all kinds of toxic chemistry with these high energy particles in the air. No, ventilation is not fast enough to save the machine, even if it might be fast enough to save you. If you do choose to try it anyway though, you may die from breathing it in before getting in any major trouble. :)|
|Thick ( >1mm ) Polycarbonate/Lexan||Cuts very poorly, discolors, and then catches fire.||Polycarbonate is commonly found in flat sheets. The window of many laser cutters are made of polycarbonate because polycarbonate strongly absorbs infrared radiation. This is the frequency of light the laser cutter uses to cut materials, thus ineffective at cutting polycarbonate. Polycarbonate is a poor choice of material.|
|ABS||Melts||ABS doesn't cut very well. Lasers cut by immediately vaporizing material, and ABS only melts. It thus has a higher chance of catching fire and putting frustrating goo on the cutting surface. Doesn't engrave well either for the same reasons.|
|HDPE/milk bottle plastic||Catches fire and melts||It melts, and turns into goo. Don't use it.|
|PolyStyrene Foam||Catches fire||Only thin pieces cut. This is the MOST common material to cause laser fires.|
|PolyPropylene Foam||Catches fire||Like PolyStyrene, it melts, catches fire, and as it drips, those droplets continue to burn and leave little burnt balls everywhere.|
|Fiberglass||Emits fumes||Neither of its components can be cut with a laser cutter. Glass can only be etched, and the resin that glues it together lets out fumes that aren't fun.|
|Coated Carbon Fiber||Emits noxious fumes||Only plain carbon fiber mat can actually be cut, but once coated its a lost cause, and the fumes are dangerous.|
Metal cannot be cut on our CO2 laser cutter. This requires a significantly more expensive fiber laser cutter. However, metal can be etched with the use of a metal etching coating (cermark), or for anodized/other coatings the coating is etched off, leaving the bare metal behind as a contrast.
The danger with attempts at etching/cutting bare metal on our machine lies in the fact that metal is very reflective and more conductive than other materials, meaning it requires more energy to be vaporized. At best, our laser can temporarily melt the surface of metal, which increases the danger because the “micro-pool” of molten metal will immediately level itself, creating an excellent mirror, which then reflects the laser's beam straight back into itself, potentially ruining the machine if the beam finds its way back to the laser tube. In short, don't attempt to cut metal with our laser.
Note: This panel uses capacitive touch sensors on its control buttons, so there is no physical actuation to be felt. It is quite sensitive, and therefore can be activated whenever in contact or near contact with skin; this means they can activate via contact through clothing (like a T-shirt). Please BE CAUTIOUS when leaning over the laser cutter around this area for these reasons.
The control panel uses 10 total buttons.
From left to right these are:
Four Arrow buttons: In xy jog, and z jog modes, can move laser head or raise/lower platform. During a job the up/down arrows let you change the job power on the fly on a scale from 0 - 255.
There are 4 main areas of focus on the machine's LCD display.
This section gives step-by-step instructions along with photos to reference while walking through them.
1.) Water Chiller:
The water chiller circulates water through the laser tube of the machine. This is important because the plasma arcs generated within the tube can create a lot of heat, which needs to be removed.
Our main concern with the chiller is ensuring that all of its connections are secure and going to the correct places with no leaks, and that while it is running, no air bubbles are cycled through the laser tube.
There is also a connection for the chiller alarm; the connection is next to the water tubes.
There are two tubes coming from the chiller. Make sure that these are:
The chiller directs water continuously through the laser tube and maintains the water at or near room temperature. However, to maximize the life of the laser tube, we must make sure that heat is removed evenly from the tube by ensuring there are no air bubbles present. Air bubbles create local hotspots along the tube, which will ultimately reduce the tube's life over time.
After turning on the water chiller, often bubbles can be observed entering and leaving the laser tube. Watch all of these bubbles leave, and search for smaller bubbles (they generally get caught at the ends of the tube). There may be some minuscule debris inside the tube, along with persistent bubbles of similar size, that we cannot remove without specialized equipment, but its impact is relatively small; thus it can be ignored.
For other bubbles, (generally identified as those that appear to “wiggle” in the current) they can usually be moved by gently squeezing one of the input or output tubes, and quickly releasing it. The sudden slowdown and rush of water can dislodge most if not all bubbles that can be moved. You can see the bubbles present in one photo, and gone in the other above.
2.) Air Assist:
Our air assist compressor provides a steady stream of air that projects from the laser head onto our cutting surface. It allows the laser to make cuts that would otherwise ignite the working material. While the air assist should always be used, it does have one downside. When working with lighter materials, the stream of air very easily blows away parts intended for cutting.
Please check that the air assist is connected to the correct input port. It turns on when plugged into an electrical socket.
3.) Exhaust fan:
The exhaust fan blows away smoke and other potentially harmful vapors created while cutting. Simply slide the blue exhaust tube from the back of the laser unit onto the exhaust fan's input port, and route the output tubing outdoors.
The fan can be powered on by plugging it into an electrical socket.
After many uses (perhaps prolonged periods of disuse), or after moving the laser cutter, the mirrors may come out of alignment, and though it may not always be obvious, the cut quality will suffer. If the laser has not been operated for an extended period of time, quickly run a check to see if the laser is still in alignment.
Fortunately there is a fairly simple process for checking and realigning the mirrors, and it is found in the manual, which is included in the “required items” section of this tutorial.
The method of realigning mirrors requires thermal paper, but I used old receipts for this purpose. You may consider storing thermal paper or old receipts in one of the compartments on the laser unit for this eventual purpose.
Note that the peripheral devices will likely all be plugged into one surge protector, so some of these steps may be redundant.
Machine power-on steps:
The RetinaEngrave3D software is the cutting software made by Full Spectrum Laser. Through it, we get our design files onto the laser cutter. It is here that we specify power, speed, layers, etc..
RetinaEngrave3D can generate rasters from .bmp, .jpg, .png, and .tiff by dragging and dropping. However, other file types require being saved as an .xps file, or can be directed into RetinaEngrave3D through the Full Spectrum Engineering Driver, which is the primary way images are put into RetinaEngrave3D.
The process is simple. From whatever program you are using, go to print and select “Full Spectrum Engineering Driver” from the options. Your file will appear in the RetinaEngrave3D software, allowing you to manipulate its size, settings, and other options to begin your cut.
RetinaEngrave3D has the option to create simple images within the program that do not require any special changes to run as a raster or vector cut. I recommend this option if you only need a simple shape/text in a predetermined size.
Once gone through the print driver, RetinaEngrave gives a few options to manipulate your image on the left. Those options available include rotating the image 90 degrees; mirroring the image vertically or horizontally; dithering to different extents; and resizing the image. Within the vector cut tab, there is also a vector cross-hatching option, but that is beyond the scope of these instructions.
At the top are more controls that concern engraving. Below is a brief list of their functions and usefulness.
Before beginning your cut
Triple check that the laser head is positioned where you need it.
You can use the arrow keys in RetinaEngrave to move around the laser head, or with the laser control panel in fast xy or slow xy mode.
For this step, you can use the up/down arrows in the slow-z or fast-z modes on the laser cutter; using fast-z to get close, and then slow-z to reach the final touching point.
The focusing ruler (pictured above in use) should be sitting behind the left y-axis track in the laser cutter. Use this on the ledge of the laser head, and raise/lower the head until the end of it just touches the surface of your material.
Using the option to run the perimeter (4 corner arrow icon) in RetinaEngrave, you can verify the edges of your cut. This should always be done to ensure you've gotten the right scale, or that your cut fits on your material.
Beginning the cut: Simply press the start button in RetinaEngrave. Your raster engrave will begin almost immediately. If in vector mode, the software will first process the image, and then begin the cut; that mode was not covered here, so if you intended to do a raster engrave, and the machine pauses before cutting, you may want to hit the “C” key to cancel the cut.
This tutorial's objective was to get a student up and running with the FSL Pro 36×24 Laser Cutter.
Speculating future work derived from this tutorial, you may want to consider reviewing 3D projects created using a laser cutter, and an alternate post discussing engraving and cutting a variety of materials. In the big picture, the problem of disseminating knowledge about the laser cutter can be solved with this tutorial.
For questions, clarifications, etc, Email: [email protected]