That entirely depends on your tolerance for pain, and your attention to detail. As you get into larger printing, your troubles are going to increase exponentially. I could argue it would even be cubic. So if you go from 8" machine to a 32" machine, I think a conservative estimate is 64x the problems. I’ve never tried anything that large, but maybe someone who has can agree/disagree.
I bet it’s even worse than that. I can’t imagine getting the first layer down with 9 square feet of bed…
8"x8", and you’d have to be a little patient because it is a combination CNC/printing machine, but still probably not bad. This machine is better than a proof of concept, but not as good as a dedicated printer this size and price. This is a pretty typical sized machine. I have sliced (but not printed) prints that take 24 hours in this build volume.
16"x16" (8x the volume) and it would be doable. Your prints would be in the 1 week time frame if you aren’t changing the nozzle/layer size. Quality and reliability will significantly suffer compared to the smaller machine. Even at this size, you need to understand that it’s not just a bigger volume. There will be problems, and you’ll have to find out what they are, and you’ll have to become an expert at using your slicer. At this size, you’re already way into custom parts. Finding a heated print bed this large, and being able to make it level enough to not warp is going to be a challenge.
24"x24" (27x the 8" volume) and you’re going to have to be a passionate artist and engineer, diagnosing your own problems and finding unique solutions. You could easily slice something to take 4 weeks to finish in this size with a 0.4mm nozzle. A 1mm nozzle would let you go to 0.6mm layer height, which would mean 1/3 the layers, so still in the 1 week time frame to fill this build volume.
32"x32" (64x the 8: volume) and you better be obsessed with it. It will take a lot of enginuity, patience, creativity, and intelligence. And pain tolerance. Lots of pain tolerance. It could literally be printing for months.
Like I said, I’ve never tried anything this big, but I can’t imagine it would go well if you weren’t really passionate about it. I totally trust that Dui has his big printer humming, and he can make some fantastic things with it. I’m sure it’s the right size for him. But if you don’t own a 3D printer, or you just have one you bought, but don’t know why it sometimes doesn’t work, then you really need to go smaller. It all depends on you.
One of the best, most unique things about the MPCNC is that the size is really pretty easy to adjust. If you really want to try it, and prove to yourself that you have what it takes, then build a smaller machine. Learn what it’s failure modes are, and then buy $10 more conduit, $20 more wires, and build a bigger table.