which calls for the use of 608ZZ bearings so that the filament spool can spin with low friction. However, when I look into it, it turns out these very common skateboard bearings are generally packed with a thick grease, which introduces its own drag and simply isn’t needed for this kind of low load application. It turns out many people will use a solvent to get rid of that grease, and then their bearings spin more freely, but that is an extra step and extra work. Surely the bearings with the same dimensions but without the thick grease can be purchased instead? If so, what would be the model number that I should order? Anyone know?
Reporting back: apparently a plain 608-open bearing will do the job. Oddly enough, these seem to cost more than the ones with the grease and the covers. Economies of scale I guess.
Not as easy to find: ABEC-1 608 open bearings, as these have a lower tolerance and thus less friction for an application such as this.
Better still would be hybrid ceramic bearings, and then best overall would be fully ceramic bearings, but those come at much higher cost.
If you print mostly functional parts, then probably someday you’ll also want to know. Well, now you know.
You know talking to yourself is the first sign of madness. Sooooo…
About the bearings. I’m in the wash them in solvent camp, pry the dust seals off and give them the once over before a light silicone lube and seal up again. I mostly use the cheap amazon ones so inspection/service tends to be a necessity. Those boxes look cool though, I’m kinda tempted to inspect closer as an enclosed AMS type thing for my A1Mini.
I’m not even sure it’s strictly necessary, given that sitting a spool on the metal rod behind the X1C would, I’m guessing, have even worse friction than 608zz bearings, yet seems to work ok anyway… But I figured if the cost is low enough, then I can for sure move forward and not ever have to look back.
I thought that with all the fidget spinners around, maybe the better bearings would be similarly cheap. Maybe I just haven’t yet found the right place to buy them… Or maybe I should 3D print-in-place some bearings using nylon or something. That might even work. They could be printed directly into the model without having to press-fit them later.
Once you spin the 608zz bearings a few times the grease drag goes way down. I’m using a much simpler roller setup in my cereal boxes. The bearing spin very easily.
Reporting back:
I ran the experiment, and the results were completely opposite of what I would have thought.
I was willing to buy what I thought would be premium, branded bearings just to have guaranteed good results. So, to do the A/B comparison, I purchased both 608zz and 608-open from the same PGN brand:
and neither one spins very well. Not at all! I thought that at the very least the 608-open would spin better, but no! And it’s even advertised specifically as a fidget spinner bearing.
So, for a third comparison, I dug out some never-used, far less expensive 608zz bearings I had purchased in 2018 for $13.58 for 50 of them:
and they spin so much better that it’s practically a joke, even with all their original grease and seals still intact.
So, go figure. For something as seemingly commodity as 608zz bearings, there’s definitely differences that may matter for a low load application, but evidently not differences one can detect from either price or description on an amazon listing.
Fair point. Who is the mouser of bearings? If I have to order from an industrial tool house like MSC, then it will totally defeat the point of using a cheap bearing in the first place.
I used this model but if you read the make, I had to modify it for my use. I don’t know how to share my files but you’re certainly welcome to them if you figure out a way.
These are the bearings I bought. They were greased but I spun them with a drill and they had little or no drag after that. I can set an empty filament spool on my spool supports and it will turn freely.
@NeverDie i actually did print in-place and used it for rewinder and one model, but used ABS, should have used probably PC . It turned ok-ish added a little oil and used a drill hep initially , worked, but at the end replaced it with 608 low friction sealed from local supplier (expensive). Note that this was the time when i did have tolerances around 0.1mm and now is 0.05mm with better tunning. and had to print a few before got them nice good for fun trial but not sure is worth the effort . May be worth trying it again with PC . And keeping it as sometimes for small things just ok
Reporting back: Out of curiosity I ordered and received some hybrid ceramic bearings from aliexpress, and they have the least friction (spin the longest) yet:
Overall less expensive than the mouser of bearings.
You might be surprised to see how little load and work those bearing have to do holding a roll of filament…
Back in the day I got a new printer where you were supposed to use half sized rolls inside the build chamber - what a pain and at what price…
I make some lid spacers to double as spool holders.
And of course I wanted proper ball bearings…
Meant having some 8mm rod of sorts, at least one bearing either side and with all that a lot of added weight on my flimsy mounts…
Than I had one of these lightbulb moment from the cartoons…
At best just over 1kg of load on those bearings, no high rotational speeds either and with all those teflon tubes already more than enough friction in the system…
Had an old printer waiting for enough space in the rubbish bin…
Salvage two smooth rods from it, cut them to length and that was my axle.
Two little , printed stops on the ends to prevent the thing from slipping out and I was left with the spool problem.
With that the various core diameters to deal with…
I printed a cone able to fit all diameters for both sides of the spool and with a big, coarse thread to secure them together.
And then just a matching hole for my axle…
Expecting failure I printed the cone screws/nut with as little infill as possible and only two walls.
Printed in PLA…
Of course I added a bit of silicone lube on the axle to help with friction and wear.
How long did it last?
No clue as I sold it two years later with the rest of the printer…
I guess around 60 rolls of filament went through it and there was still no meaningful wear on the tine hole going through the PLA…
They could be printed directly into the model without having to press-fit them later.
