A few thoughts after four days with the CORE One  

A few thoughts after four days with the CORE One

This is not mean as a "review", just a stream of consciousness after a few days of printing with the CORE One, mostly PETG and ASA. Like any new model, this one has quirks, which I'm sure Prusa will work out through firmware upgrades and improved parts. Its current state reminds me of my XL (one of the first to ship), which had quite a few issues when it arrived but is now a wonderful printer. 

So far, it's a resounding "meh". In my eyes, the Mk4S was an evolutionary dead-end street. Marginal improvements over the Mk4, without addressing some major issues such as less-than-perfect "always-perfect" first layers for myself and what seems many other people (as judged by Github reports). I was hoping the CORE One would be a major step forward but it just doesn't feel that way. It's a bit of a Frankenprinter. Obviously, it's a Core XY design, but for better or worse, Prusa wanted to provide an upgrade path from the Mk4S, so there's still that legacy everywhere. The XL with its tool changer and large volume was "wow". The CORE One still feels like a MK4S, in an enclosure. 

Looks are fine; nice orange accents against a metal black background. But after a few days, I can't shake this thought that it reminds me of the Boston City Hall, in its Modern Brutalism look and feel. Its design language seems to cater to the typical Prusa enthusiast/tinkerer more than the target audience for, say, BL machines, with their sleek industrial design looks.

While the heavy use of metal makes the printer look sturdy, some aspects of the build are less impressive. Side and top panels are held in place by what I can only describe as super cheap rivets. The fact that they include a whole package of 50 spares should tell you enough. In fact, my machine arrived with more than half of them popped out during transport. The top slider to let air in for PLA and PETG prints also feels cheap and wobbly. The metal crossbar in front blocks view of the hotend when the sheet is close to the top and makes it a tad harder to reach the nozzle to remove debris. 

The side "pockets" are an interesting design decision. Fine, maybe even great, for people for whom this is their only printer. But for anyone with a row of them next to each other, it's not going to be convenient (so far I have only one but more are coming to replace my Mk4S's). I've seen some cool ideas on Printables for using the left pocket to store stuff, but again, that's great if it's your only machine and you have easy access to all sides but doesn't work too well if the next printer sits right adjacent to it. After a fews days of printing I'm in the process of contemplating options to feed filament from above instead of the side, which I don't find convenient. Plus, the small PTFE tube that acts as the filament intake sits in my opinion too close to the edge of the printer, and with full spools I've had several situations where the filament jumped off the right side of the spool when trying to load it. 

The CORE One is the first Prusa printer that comes with an integrated enclosure. Thankfully I haven't had any reason yet to find out how much harder that makes it to fix things.  Functionally, the enclosure seems to work well. For my ASA prints, it kept a nice steady internal temperature. Some interesting changes to the startup gcode. The printer will now wait for a certain minimum chamber temp, while the nozzle temperature is going down to a lower idle temperature, as defined in Filament Properties. It also goes through the same bed heat assimilation step as the XL. For the XL, I see the point of it, here with the smaller bedsize, I'm not so sure. I've skipped it a couple of times, without any obvious issues (but it may be crucial for good first layer performance, see below).

They really skimped on the lighting inside the enclosure, which is minimal; a few more LEDs wouldn't have hurt at that price point. 

One excellent design change is that they ditched the Abominable Print Fan of the Mk4S. Now it's possible again to watch the nozzle and see what it's doing, and to get easy access to the nozzle for cleaning purposes.

Another good design element is the spring mechanism used by the front door. It offers a satisfying bit of resistance when you open the door. Less great is that the door handle is apparently metal. I haven't figured out yet how to replace it. My printers are "color-coded", so I like to reprint parts in different colors and add color accents to any add-ons, but it looks as if I'm stuck with an orange door handle for all of my printers.

Now why the door sensor is on by default so that the machine complains when you open the door is beyond me. It was the first thing I turned off. Otherwise the software is pretty much the same it was on the Mk4S or XL, easy to use and functional. Setting it up in PrusaSlicer and connecting it to PrusaConnect was straightforward. I use ethernet, so I can't comment on wifi, NFC, etc.

Print quality has been very nice so far. I've seen reports of VFAs but I can't claim to have that problem—or my eyes are just not able to pick them up anymore. The only issue I've come across in my limited testing is some bad horizontal top surfaces on my ASA prints. May require adjusting print profiles a bit. 

Can't say anything about speed as that's something I don't pay much attention to. It's plenty fast for my purposes, and certainly prints as fast as my MK4S. It comes with a HF nozzle, which I will replace with Obxidian soon, like I use on all my other printers. I do a fair bit of PCCF printing, so that's one less thing to worry about as I can use the same nozzle for everything.

It is definitely louder than my Mk4S machines, I suspect due to the resonating enclosure. I haven't put it on a paver yet to see if that makes a difference as I'm waiting for Prusa Support to send me the anti-vibration feet that were missing in my package. At this point it's sitting on felt feet. It doesn't help that the firmware for it doesn't have the fix for the excessive homing yet that they just rolled out in the firmware upgrade for their other models. I understand they're also working on additional firmware improvements to help with the vibrations.

Still waiting for the camera and filter. I've seen several third-party options for attaching filters, but I think I will just wait a few more weeks for the official solution; I have neither time or desire to worry about adjusting fan speeds. I haven't figured out a good way to attach one of the Wyze webcams I use to monitor my printers. I have ordered a Buddy Cam, and hopefully by the time it arrives they have figured out how to do live feeds instead of snapshots. One reason I love the Wyze cams is that they continuously  record onto an SD card, so if something goes wrong I can rewind and see if I can figure out what was happening.

At this point I haven't done any systematic testing of print quality, as I was focused on using it to get stuff printed that I had to get out of the door. And I'm not really into running speed tests, tests for overhang performance etc etc (I've never printed a Benchy in my life!); happy to leave this to others. I know what I usually print and don't need to worry about this stuff much.  

But I will do some testing this weekend of the CORE One's first layer performance, which has been abysmal on all my three Mk4S's, with a constant need to adjust live Z down for PETG to get good performance on fine first layer details and up for PLA prints to avoid waves. Interestingly, this has not been an issue with my XL so my hope is that the CORE One—being a Core XY machine—will mirror the XL's excellent performance in that category. 

The other open question is the MMU3. I really, really, hope they come up with a solution that doesn't require three times the space of the printer for the spools and buffer. There have been suggestions for a top mounted approach, which would be perfect, but I'm afraid Prusa wants to get something out quick rather than great.  I may keep a Mk4S, just for the MMU3. I'm not a heavy user of it (the XL is just much faster for multi material and multi color) but when I used it, it worked great and reliably, unlike other solutions I tried before (the MMU2 and the Mosaic Palette). 

So TL;DR, it's been — fine. Didn't have any major issues (short of some stuff like power cable and Haribo missing from my box). Print quality looks nice so far. The enclosure does the job. Some good, some not so good design decisions. I'm just not getting super excited about it. It's feels like just another printer, without the "wow, that's FUN" feeling I experience every time I use the XL, even after more than a year. If this had been the successor to the Mk3S, I would probably be psyched, but the Mk4/Mk4S generation in between has worn me down, and the CORE One is clearly a descendant of it.