[Anycubic ACE Pro] Improve filament path design for smoother insertion

There is not enough information out there about Anycubic's multi-material solution, so I thought I would put together some thoughts as a guide to people considering this system and the broader Anycubic ecosystem and compare it to some of the other options. **First some background**. My first 3D printer was an Anycubic Kobra in 2022. Yes, the one that started the series. It was a Marlin based printer in the well-understood bed-slinger architecture of Prusa mk3 and Ender fame. The printer was capable of some outstanding quality, but it required dedicated attention since it was easy to lose z calibration and other mechanical parts required regular adjustments. Eventually I made it into a klipper machine and this improved speed together with my understanding of what was going on. The Kobra acquisition was quickly followed by a Kobra Neo, which I got from the refurbished Anycubic store in Ebay. The Neo is almost identical to the Kobra and many parts are interchangeable. Incidentally I soon had the opportunity to interact with Anycubic support when one of the axis motors failed. The interaction was great. I explained the issue, I showed that I had checked the motor with a multimeter and they sent me a replacement without any issues. My interest in 3D printers quickly evolved into the purchase of a Bambu Labs A1 mini with their AMS lite, followed by a Kobra 3 with ACE pro, followed by a Qidi X Max3 (refurb), followed by another Kobra 3 (refurb), a P1P with AMS and my last acquisition a Flashforge AD5X. Why am I saying all this? Because I am deeply interested in these machines and am familiar with various systems. For this review, I am able to compare the ACE Pro with the Bambu Labs AMS (original), the AMS lite, and the Flashforge IFS system. As for what is missing, I have no direct experience with Creality's CFS or with the Qidi Box. **My experience with the ACE Pro**. Let's start with the problems I've had and how to address them. I have both my ACE's connected each to a Kobra 3 (first gen). Starting from the moment the filament is ingested into the ACE and following along: Sometimes the filament is not directed along the intended path in the ACE and exists at weird points of gets stuck. A very common reason for this is the filament having a curve or being inserted at an angle. It is easily addressed by straightening the filament before insertion and inserting from the perpendicular to the opening. However, this should be addressed in a next generation by providing a better confined filament path. Another, less common failure, is the filament getting stuck in the buffer, which is a little component with springs close to the exit path of the filament from the ACE. It is easy for the spring mechanism to become dislodge and prevent it from working smoothly. Often a single filament bay will be affected by this until fixed. The fix is fiddly because of the number of small components that need to be precisely positioned, but it is also a cheap pre-built replacement piece. The exit path of the ACE also sometimes randomly fails if the little blue piece locking the pneumatic connection to the PTFE tube is not in place. This one is insidious because often the system will work perfectly without the blue locks, but sometimes it won't. Of course the manual does instruct to place the locks, but those things are a pain, so sometimes I forget. As the filament exists the ACE, it now travels all the way to the head and the 4 way splitter. This is where another problem can happen. It is relatively easy for the filament to get stuck in that 4-to-1 splitter. The PTFE tubes need to be inserted *aggressively* all the way down. Some of the printers come with PTFE tubes that have actual marks indicating how deep the PTFE tube need to be inserted, but nowhere is there an explanation of this. I have also found that even when inserted correctly, the tubes can loosen up over time and creep up, leading to a failure to load the filament into the hotend. Finally, inside the hotend, there is a filament presence detector that depends on the precise placing of a tiny spring. If for whatever reason you need to disassemble the hotend completely, this little spring is likely to jump out into the void and become forever lost. It is also tricky to place correctly and the whole filament changing process will not function correctly without it. This is not documented well enough. Having said all of this, these printers and the ACE system are absolute workhorses. They exchange filaments reliably and are fairly easy to diagnose when problems arise. A few things that I really like are: The whole Anycubic ecosystem shares a single ACE Pro model, no changing systems as you move from bed slingers to CoreXY like Bambu does. The ACE was the first multi-material system to have an integrated filament dryer and it does not get nearly enough credit for that. To this day it has significant advantages with respect to others, such as being able to run while a print is happening. Also it can be started or stopped completely independent of what is going on with the printing both from the printer and from the app or computer. An aspect that I don't see mentioned anywhere is that the ACE pro works well with cardboard spools. I use cardboard spools in the ACE Pro regularly without any issues. I tried the same with the Bambu AMS and I quickly understood why everyone warned against it. I am not sure why this is the case, but it is my experience. **Anycubic ACE Pro compared to Bambu AMS and AMS lite**. In my experience, the ACE has a few advantages with respect to the AMS. The main mechanical and reliability one is that it keeps the four filament paths separate until they exit the device. Any time filaments need to converge in a splitter there is a good chance of a failure point. By keeping this aspect out of the ACE, it is more reliable and easier to debug. Another nice point is the integrated drier and the good performance with cardboard spools. On the minus side, only two ACEs can be combined for a total of 8 colors vs the 16 of the AMS. Compared to the Bambu AMS lite, things are far less clear cut. Mechanically, the AMS lite is the most reliable multi-color system I have used. It can use cardboard spools with no issue and maintains independent filament paths all the way to the entry to the hot end. Overall, Bambu's AMS lite with the splitter for the A1 system printers is incredibly reliable, far more than the Anycubic option. However, the AMS lite is open (no drying), it is oddly bulky, and can only use a max of 4 colors. **What about Flashforge IFS**? The IFS is a super compact 4 color system mounted on the side of the Flashforge AD5X. I have not used it nearly as long as the ACE or AMS, but I am extremely impressed. It has independent filament paths all the way to the hot end, it is extremely compact, and because of its location, the PTFE tubes to the head are pretty short. This means that you can print flexibles such as TPU through the IFS and get multicolor TPU prints. Flashforge does not officially endorse this any more, but in my experience it works beautifully and is a unique ability among all of these multi-color systems. The Flashforge seems to take the best parts of the AMS lite and make them even better (more compact, flexibles compatibility). It does not address drying or more than 4 colors, but it is a fantastic system at an incredible price as a bundle with the AD5X printer. **What about Creality CFS and QIDI Box?** Sorry, I don't have any Creality machines or a Qidi Box. Someone else would need to chime in. Hope this helps others make an informed decision when deciding what printer + multi-color system to buy.