I haven't dialed in PLA yet, but I had a fresh roll of Prusament PETG around, so I started testing my direct-drive Hemera. I printed a cube, then just started cranking out 0.2mm benchies at 40/60/80/100/120 mm/s. I haven't had a printer that was useful at >100mm/s since my ultimaker. (40 on the right up to 120 on the left) This is with the hemera direct drive. I'm impressed with the motion systems ability to throw that 450g around! There was a bit of ringing on the hull at 120mm/s, but really there was some ringing all the way down, the spacing just changed. Here's 120: The surface tended to get a bit more matte as I moved faster, not sure if that is the speed, or the fact that I moved up to 250C from 240 once I hit 100mm/s. PETG is my go-to material for functional prints. I'm pleased I can crank things out a bit faster than I have been. I am not going to take the ringing too seriously until I get a solid table for the TC. I'm on a pretty solid table now, but it has some side-to-side wobble and I can feel the printer coming through. Tomorrow I'm building a dedicated low table for the toolchanger.
Keep in mind that once you go over 100mm/sec you will get effects simply from the momentum of the material as it is deposited regardless of your printer's HW. PETG, like TPU, starts to get micro bubbles as you get hotter and hotter. Most PETGs I have used have a relatively small window of optimal temp. 230-245C Most of the time 235C is optimal. Although it depends on the PETG formulation as well as how accurate your printer is. With the TC I am finding 235C to be OK.. A warning with PETG... if you get a leak or a lift off the bed and the stuff blobs into your tool and cooks, the material can crossover and not be able to melt again thereby destroying your tool. That has already happened to me once. I had to replace the thermal tube, sock, heater and thermistor. As a rule with the TC I clean off all remnant material after every print from the hotends.
Hello, 235°C +-5 is my swett spot for PETG as well. When PETG starts to bubble or smells more it will probably loose some chemicals into the air. I run a water cooling on one of my printers. And I got a lot of condensed "something" when the temperatures were too high printing PETG. There are the old pictures: http://www.rf1000.de/viewtopic.php?f=72&t=1860&hilit=glycol&start=10#p18849 or Thatwhy I do not print much when a printer stays within the living room. Else I suck the air to the outside or the printer has to stay in the basement. Greetings
