Laser Cutter Complete!

I finished my laser cutter this past week, and have been cutting and testing all sorts of things. Overall I’m pretty impressed with the buildyoucnc.com machine and support.

Alignment

Alignment is the scary part if you read the instructions on buildyourcnc. I happen to have a laser pointer that is perpendicular to it’s base (it is used for aligning photo enlarger. So I made 2 disks out of plywood with a small hole in them and placed those in the laser supports. I then aligned the mirrors so the laser reflected off the 3 mirrors and hit the surface. I then placed the laser in the supports and did a test fire, no luck. So I put a piece of blue masking tape on the first mirror, fired, then adjusted. What I found was that the final mirror needs to be very carefully adjusted so the laser fires right down the middle of the tube. It took a couple hours to get it dead on where I could get a focused beam at both extremes of the X axis.

Initial Tests

I burned through a ton of 3x5 cards, they make great test targets! I have a number of materials I want to try. I have already tried cardstock, plywood and acrylic. For those interested this 40W laser at full power goes through ¼ baltic birch plywood in one pass with a feed rate of 15inches/minute. Not too shabby

Software

In addition to being a big build your own tools advocate I also support free, open software. LinuxCNC is my choice of software to run the laser cutter. I’ll attach my ini file, but configuration using stepconf was very straightforward.

On the CAD/CAM side I primarily use Mac, and quite honestly there are hardly any good tools out there. I’ve been using OpenSCAD, but that’s not going to cut it for my workflow. I bit the bullet and eval’d Parallels and VMWare Fusion to run Windows software. I’m going to go with VMWare as it installed perfectly with little issues. I’m trying out CamBam and pretty excited about it. I’m also using dotG for rasters. My workflow is Adobe Illustrator and Photoshop, processed with CamBam and dotG, then transferred over to my Linux box running LinuxCNC. All 3 OSes share a common shared directory on my Mac.

Improvements

OK I can’t really let this go without tinkering a bit.

1. I had some issues with the water tubes going to their default positions. They would hang up when I did a full extension to the back of the work area. I have relocated those on the back panel and that seems to be better.

2. I built 2 small brackets on my 3D printer to hold homing switches. These are pretty important IMHO

3. The base build uses a potentiometer to control the voltage to the laser power supply to control the laser strength. First I put a meter on the output so I could get repeatable voltages, which got me thinking of a better way. I have since thrown together a little Arduino board to take LinuxCNC’s spindle speed PWM and output a range of voltages from 0-5V This is working great! In the video you can see a full power cut to cutout the square ¼ ply, followed by a lower pass pass to etch my initials. Pretty sweet and highly recommended.

4. The material for the base of the machine is an issue. It needs to sit up about 21/2 inches, and be impervious to laser. I had a piece of perforated steel cut at my local metal shop. That has been working, but I’m getting flash back from the metal which leaves a pattern on the back of material, and in some cases lines also have a pattern. I have ordered some aluminum honeycomb from McMaster Carr which seems to be the preferred base in commercial machines. Unfortunately that makes my goto magnetic jigs worthless so I’ll have to come up with something new.