I read over and over again, rants from novice 3D printer users about the size of the hole in the spool of filament. They assume the manufacturers are total idiots with their usually large diameter center hole they build into their spools.
When I first started 3D printing, I was thinking along the same line. I was questioning the huge center hole. It was a very easy “first task” to print a spool hole size adapter. Lots of them are freely available. So, I did. In two sizes to match several manufacturers spool hole size.
I was then frustrated by excessive “spool-off” of the free and easy spinning spool. Winding layers would become loose on the spool and if I ever had a “snap-back” of the filament onto the spool when changing colors, the end would bury into the loose windings. Digging it out would sometimes create cross-under of windings.
This “snap-back” is the source of the hoax about crossed under windings of filament from the factory. It is impossible to have crossed under winding on a continuous wound spool. If it was (and truly it isn’t) there would be a heck of a lot more products on spools that would have the problem. There isn’t. Every construction crane, sewing machine and fishing rod in the world would not function. Period. Not open for discussion. Think about it. Don’t be ignorant.
If you are thinking back-lash as in a fishing spinning reel, that’s a totally different cause and effect.
Of course, always check the free lay of the initial layer when first loading a spool. That’s always a user responsibility.
I realized the manufacture wasn’t being ignorant about the hole size either. The hole is large so it will hang off center on the spool support. The inside edge of the large hole is purposely smooth. This induces a bit of drag on the filament when un-spooling and keeps the windings in place on the spool. No over-spin. Using the center hole adapters are not necessary. They are not required. They defeat the well thought out feed design of the manufacturer. Drag on filament feed is a good thing.
The stepper motor filament feeders have plenty of reserve force to overcome spool drag. Even the Bordon tube style. Compare the force required to hand feed the filament into a hot print head to the force required to pull filament off an off-center spool. The spool pull force is insignificant.
In my opinion, a metal shaft axis makes a smoother low resistance support than a plastic to plastic axis. I have one holder that is a chrome tube and the other is a small threaded rod. The threads do not cause any feed issues. (See pictures)
I have explained spool hole theory. I have now consumed over 30 different spools of filament with no drag issues and never experienced a factory crossed windings on any of them. You have been told the “Spool Hole Theory” ... What you choose to believe is your own decision. You (and I) always have the option to be wrong or choose our own belief.