About the Training Session
After I bought my Rayjet50 two years ago, I had an online orientation/training session with Miguel Michado, a TroCare specialist. It was quite informative and helpful, and I’ve corresponded with him a number of time since then on technical questions I’ve had. About 6 months ago he contacted me about their TroCare program and I signed up. As part of that package, they offer online training sessions.
I am planning on a number of projects with different types of acrylic, and felt I could benefit from a bit of one-on-one discussion. I emailed him a couple of months ago and posed some of my questions. Over the course of a few more emails he answered some of them and I compiled a few additional ones, which formed the basis for today’s session. This was the last one with Miguel, since he has moved to sales. He is replaced by Timothy Entin, who also participated in the session. As always with Miguel, it was a great session and I got a bunch of useful tips.
While the session loosely followed the script, it was also a bit fluid and covered the questions and a bit more. Rather than list the questions, I’ll summarize what I was asking and the answers I received. Hopefully that will be more coherent than my original questions.
Parameters for Cutting and Engraving Acrylic on the Rayjet50
Its all about the parameters—power setting, cutting speed, and ppi/frequency. The Rayjet50 has a 30 watt CO2 laser in a metal/ceramic tube. Like all laser cutters/engravers you can use a test design to determine the best settings to cut or engrave a new material. So far I’ve done mainly wood. I’ve been looking for a parameters database specific to this machine with not too much luck. Here, in no particular order, are my takeaways from the discussion.
Extrapolating Parameters from Another Machine
There are lots of parameters lists available for many different brands and models, but since different models have different power ratings and different speeds, extrapolating from one of them to the Rayjet50 can be a PITA. The gist of the discussion was:
- Power. Power setting is usually stated as a percentage of the laser’s power. If the other machine also has a 30 watt laser, one can assume that the power setting is a good starting point. The further away from 30 watts it gets the more difficult to extrapolate. A 90% setting on a 30 watt laser is 27 watts, while a 90% setting on an 80 watt laser is 72 watts.
- Speed. Speed setting is also given as percentage of the laser’s speed. This is a reference to how fast the focusing lens is moved over the maaterial in the x/y directions. The machine’s specs should show its travel speed in mm/sec or inches/sec. The Rayjet50 has a max speed of 60 in/sec. To extrapolate speed settings from one machine to another, you need to know the max speed of the machine and then use the speed setting (percent) to determine what the actual speed is. Then you can work backwards to determine the matching setting on the Rayjet50. A setting of 50 on the Rayjet is 15 in/sec. A setting of 50 on a laser with 200 in/sec max speed is 100 in/sec.
It is a bit of work, but it can be done as a starting point.
Parameters for Acrylics
Acrylics come in a variety of types and colours. The discussion had three topics:
- Cutting acrylics. What effect did type, color, or layers have on cutting parameters? All acrylics, whether cast or extruded, coloured or clear, single layer or multi layer have similar cutting parameters. Dialing in the settings for one type will get you close for other types. 60% power/40% speed are good starting points.
- Engraving acrylics. Same questions. Engraving is a different issue. Engraving effect (smooth or stippled), acrylic colour, and acrylic treatment (smooth, textured, metalic, or sparkly) and depth of engraving all affect the settings. Each case is different and can require running a test pattern to determine the optimal settings.
- Offsetting the laser. When and why for acrylics? Offsetting the laser focal point by 0.09″ above the surface when engraving acrylics produces a smoother raster engraved surface. Having in at the surface produces a more textured effect. The second use case for offsetting is when you are doing vector cutting at engraving level settings so that the line is partway into the material. Depending on the offset (up to 0.15″), the line can be considerably wider than a standard laser kerf. The advantage is a significantly faster production time. The third use case is setting the cut focal point half way through the acrylic, especially for acrylics up to 8 mm.