I run a 10W laser module on my Primo. I love it, but larger projects can take lots of time, and there are issues with larger projects. For example, I made a tray (open top box) for our cupboard for storing Tupperware. It was roughly 22" x 28" x 4" and was made with 5.4mm plywood. The base took 50 minutes of cutting, and the whole project took 150 minutes. When I start adding nice design cutouts on things, cutting times go way up.
With my Primo, engraving takes lots of time. A full engraving on a 4" x 4" tile takes around 75 minutes. If I increased the tile size to 6" x 6" it would take around 165 minutes. If I try to increase the speed or acceleration, unacceptable artifacts creep in. So, for engraving, the larger size of a Primo or LR3 does not provide benefits.
With larger projects, I also have the issue of warped stock. I buy most of my wood from the big box hardware stores, and it is not perfectly flat…especially across a 24" x 24" piece. My laser has a larger working distance, so I can work around minor warping, but most diode laser modules on the market have very little working distance. The laser will end up catching on edge of a cut in the stock and ruining the cut. Even with my larger working distance, I’ve had this happen to me.
I would be using a diode laser as they’ve been dropping in price and getting stronger in the past years.
My perception is that, over the last three years, the price per watt of diode laser modules has gradually gone up (a bit faster than inflation). But more importantly the power of lasers has gone up dramatically in that time. While not a perfect match, you can expect to pay around $250 for 10W module, $500 for a 20W module, $750 for a 30W module. Machines with 40W modules are appearing, but I’m not seeing sales of just the modules (yet?).
I could build a big mpcnc without a z axis.
For laser cutting, there are benefits to having an active Z axis. Often cutting is done in multiple passes, and an active Z allows the laser head to drop a bit on each pass. This drop changes the focus point in the wood.
I’ve been eyeing buying a laser engraver. Price and performance have me eyeing the Longer 30W and 40W (preorder) machines. With a working area of just under 18" x 18", it would handle 95% of the projects I’ve done over the last couple of years. I’m only hesitating because it is still a lot of money when I have a working solution.