@mrehorstdmd said in What's the most key point when you decide to get a 3d printer:
@stephenleeeyan In FDM printing, you're always trading print quality for print speed. If you want to use your printer to mass produce some parts, then worry about speed. If you're printing for a hobby, doing a lot of one-off prints, what difference does it make if you have to wait two hours or four for the print to finish? It's not as if you have to watch the machine running the whole time. Start up the print and go do something else. I frequently start prints just before I crash for the night. When I wake up the print is done.
That, of course, requires a reliable printer that you can trust not only to finish the print but also to not burn your house down. A lot of cheap printers aren't reliable. What good does it do to print at 300 mm/sec if the prints fail 3 out of 4 times, or you have to watch the machine and tweak it while it's printing?
If you're shopping for a printer and they claim that it prints at 200 mm/sec, but they don't have detailed photos of prints made at that speed and at lower speeds, chalk it up to marketing BS. It's relatively easy to make a mechanism move very fast, but much harder to get the extruder to behave the way you want when it's printing fast. It takes a lot of testing and tuning to squeeze the maximum quality out of a fast print, and that quality will generally not match the quality of the same print run at a lower speed.
If the part you're printing is small, and you try to print at 300 mm/sec., the extruder will keep laying hot plastic on top of hot plastic and pretty soon you'll end up with a blob of plastic instead of the print you thought you were trying to produce. You need a lot of print cooling power to make small prints at high speed, just like you need a lot of heater power in the extruder. If you don't have the cooling power you can print in very thin layers so that the extruder is squirting out less plastic on each layer, so it cools quicker. But then you have to print more layers so in the end your print was running at 300 mm/sec, but finished as if it were running at 50 mm/sec. You'll have a nice looking Z axis in the print, but you also have all the artifacts that are characteristic of 300 mm/sec motion.
Thank you so much for this detailed reply. I find many machines tell that they can go with 150mm/s, but actually they can only go with 80mm/s. How to choose it?
