Loud and Hot?
Two questions in one here:
First, I'm new to the MK3S, but not printing (I also have a Duet3D driven CR-10) - that said, my MK3S seems... loud? Almost like bearing noise or some harmonic in the frame. I followed the u-bolt tension instructions to the letter. Only when it's really "moving" with some speed (PLA .2 Quality Preset). Every print still comes out basically perfect, so maybe I'm just being picky...
Second, the extruder stepper seems to get quite hot (standard PLA temps), no enclosure. So much so that after an hour or so of printing, I can't hold my fingers on it for more than a second or two. I've checked and rechecked the idler tension, though there is some subjectivity there. I've seen a number of models for cooling fans, so I don't think I'm alone. I guess the question is "how hot is too hot?", and correspondingly, should I be worried about the change in moving mass of the extruder assembly if I add a fan/shroud to cool it?
Cheers!
RE: Loud and Hot?
Did you lubricate the bearings before you installed them? If not, put a couple drops of light machine oil on the rods - both sides of each bearing - and work the extruder and bed back and forth to try to work oil into the bearings. This is a temporary fix until you tear the printer down and do it right. Check the LCD for the BELT tension numbers. They are worthless indicators of belt tension, but if they are lower than 240 the motors are working pretty hard to move that axis and indicate something is too tight (bearing retainers are often too tight and cause noise and printing problems).
You might try running in Stealth mode - this will allow you to see if it is motor noise or bearing noise.
The extruder motor gets hot, mine ran 55-58c. Though I've never had a print problem because of a hot motor. That said, I added a heat sink and dropped the temp to under 50c. Many of us use a simple 40x40x11mm passive heat sink to cool it down. Others have added the fan and shroud to cool the motor even more, reports say as much as 20c reduction. No one has complained of increased print artifacts, that I know of.
Keep in mind ALL the motors run hot, not just the extruder. It's the nature of high torque steppers.
ps: there are some things that rattle: the LCD vibrates against the plastic is one of the louder sources. These noises are unique to each printer. I find not getting the steel sheet tight against the locating screws will make a print louder than normal.
RE: Loud and Hot?
Tim - this is all awesome info, thank you very much! I'll lube up (ehem) and report back.
RE the stepper temp - ~55C is in the neighborhood of what my "finger touch Oww" test reports. I'll ponder adding some active or passive cooling, given that nobody has reported artifacts from this.
Thanks again!!
RE: Loud and Hot?
Also - Belt tension reports back as 287 & 283, X & Y respectively. You did say LOWER than 240 was cause for concern, yes? (IE, I'm in the clear there)
RE: Loud and Hot?
280's are low friction numbers, and probably no cause for concern. As a data point, my current numbers are mid 290's but I'm using more expensive aftermarket bearings packed with synthetic grease. My original Prusa bearings gave me 260 numbers running on oil drops (they wore out before I added grease). But even a firmware change can cause the belt numbers to change, they are only a rough reference point, nothing definitive.
4 heat sinks and a roll of good two-sided thermal tape was under $20 ...