Polymaker cardboard spools work well until you get to the end of the spools. Then they become too light and do not move forwards or backward very well, and they slip. I have purchased several empty spools from Bambu, and I guess I am going to have to wind the filament from a cardboard spool to a Bambu spool when it gets toward the end of the roll.
What I don’t understand is why Bambu has Polymaker as an option in the setup, along with Bambu and Generic. Bambu states no cardboard spools, but one of the built-in choices is cardboard. When I asked tech support one time I did not receive an answer-back. If anyone has a better solution than using another spool would like to know. If the answer is Polymaker is not meant for the AMS but just for printers without AMS that’s not a good answer.
a) I have read somewhere that people have printed something to be inserted into the middle open space of the spool to add some weight b) people proposed to just rip off the sides of the spools and then use the empty spools from BL - your finding is interesting, I had the same imperession regarding the Polymaker spools to be suitable
You can use the external feed for cardboard spools so having Polymaker as an option makes sense. Not everyone uses an AMS. There are models available for rings to add to the cardboard spools that addresses some of these issues.
https://www.printables.com/model/251028-cardboard-spool-ring-for-bambu-lab-ams-parametric
For AMS directly it is a bit hybrid - up to now I didn’t have any problems and since the end of December I have almost exclusively printed with Polymaker cardboard spools in the AMS.
One of the reason for it, they have a very good flow rate (=high) compared to its price per kilo 
I found those printable rings slip in the AMS, and they don’t work worth a damn
Try printing them with the fuzzy skin option. I haven’t had any issues with slipping on those.
Cool… I didn’t realize fuzzy skin does the outside… I thought it would just do the top!?
I will rltry that. Thanks @edlboston
I bought a bunch of Overture, before I read not to use cardboard spools. Couple of the rolls worked no issue, few of them would tangle themselves up and halt the print. Was a huge pain in the butt.
I can confirm, at least with Overture, you can rip off the sides of the spools and they fit perfectly in the BL spools. Haven’t tried with a printed spool or other filament. Soon as I ripped the sides and stuck it on empty BL spool printed flawlessly.
Oh, also those printed rings that go over the spools did not work at all for those rolls I was already having trouble with. If anything, it made it worse.
For cardboard spools, someone here proposed to use electric tape, which is simply put around the edges of the spool. Have done that and works good. When the spools get light, people are using different tools to add some weight into the core of the spools.
I’ve had the “too light” issue even with plastic spools.
Looking at the Polymaker Spools I see the inner core looked large enough to do this too. I had an empty spool here so took the sides off and it will fit, but is pretty loose. So 3D printing to the rescue! I printed a simple adapter to go inside the cardboard core and give a tight fight on the spool (just a simple cylinder with a notch for the index pin). Just fine tuning the size and then will give it a try.
That´s probably the best way:
https://www.printables.com/de/model/346325-polymaker-cardboard-spool-adapter
works fine for me
with instruction video for installation 
No need to print anything. Simply cover the spool edges with electrical tape. The problem with the rings is two-fold. 1. Not all paper spools are the same size. 2. Some spools become too big when the rings are applied, forcing you to leave the AMS open.
I have been using Polymaker for years but I have always hated the cardboard reels since they started using them. I have had nothing but issues with the cardboard reels, Voksbug is correct when stating that they are all different sizes. I have two AMS boxes with 8 reels of Polymaker filament and not two of the cardboard reels are the same size. Some of Polymaker’s cardboard reels are too large to put on an outer ring for the AMS. Some of Polymaker’s reels are different sizes from one side of the spool to the other, which makes them wobble.
Polymaker should go back to their great plastic reels they use to have or if, as they claim, they are trying to be environmentally friendly then they should start selling reusable reels and filament refills as Bambu Lab does.
As for the future, I will try to use the electrical tape as suggested and maybe I will try to either rip the cardboard side off and put the filament on a BL reel or do the rewind to a BL reel specially on the wobbly spools.
Eventually your AMS will become clogged up by all the little cardboard shavings that fall off the spools from all the back and forth. They are not recommended for the AMS, but you can either print those damn rings that aren’t very good. Or you can just use those cardboard rolls on the outside spool holder to prevent the entire problem. Because even if you print the rings, you all have the weight problem and unless you add weights to the inside of the spools it’s still going to slip. Stick to plastic spools for the AMS. Use your cardboard outside for one color projects.
As suggested by Vogsbugg, use eletrical tape and put this around the rims. Works great.
The Lightness issue I over came by printing desicant holder that goes inside hub, added weight into it (still working best weight) and seems ok, well for now. My Polymaker spools I just ripe the sides off and put on Bambu spool
I have not had any issues with light spools. The AMS seems to figure it out. At first it lifts the spool up and stops, then it rewinds itself a bit to let off the pressure and then keeps on going.
i just tape my polymaker spools with ducttape and keep printing
I made the Spool adapters that you are talking about and i thought they were great until i went to use them. The clips that hold the original spool to the adapter spools are not tight and the spools slip. Here i am referring to using spools of smaller sizes with the adapter that increases the size to the standard 2.2 pound spool. I finally solved this problem by making a a 2 spool winder. There is a standard spool on one side and a spool of the same size or any other size. Both sides have a 8mm rod that goes through about an inch of bearings thick and are held in a adapter. In one of the adapters I also have a 1000 rpm motor that i varably adjust using an adjustable power supply using a M18 Milwaukee battery. GEARS and clamps are made with PLA CF. ALL THIS is nounted to a 4x4 about 3 feet long. It’s sime and it works great. Materials were cheap and purchased from Amazon. Could use anything for power. Need to post a picture or short video if someone can tell me where to post. It solved all my Spool problems so far