I’m posting to the custom built and Reprap because this is one of the printers I have and the most “bearing” on the issue. Pun intended.
Which brings me to the subject of radial bearings. I watched Tom’s guide on radial bearings where he indicated that the lighter loads we put on these bearings in our printers probably doesn’t make much sense to upgrade them.
In the X carriage my radial idler bearing of my Chinese Reprap that guides the belt doesn’t seem to bind when loose in my hand, somehow seems to contribute greatly to the left-right friction when attached to the carriage and stepper motor.
Of course, its hard to judge how much of that tightness is the stepper motor and how much is the pulley bearing. The carriage itself rides smooth as glass in free statel.
From my roller skating days, I do know that there are premium grades of bearings. In roller blades, the high end 20 years back were ABEC5 bearings, now it looks like the upper end are ABEC9 and ABEC11 bearings. Going from ABEC3 to ABEC5 then meant a world of reduced friction.
Does anyone here have any experience upgrading their radial bearings for the x-carriage? I mean, we’re only talking a few bucks, but I’m generally wondering if it makes a difference.
Ideas?
If you feed a bolt through the bearing then turn it in your hand while applying significant sideways force to it does it still turn freely? That should tell you if the increased resist is the bearing or the motor, but I’d guess it’s mostly the motor.
In my experience cheap Chinese bearings are just fine, but you need to get about 50% more than you actually need to account for the bad ones. You may just have a bad one that’s not obviously bad there.
Thanks. I’ll disassemble the pulley side tonight or tomorrow and see if I see some resistance. I have other Chinese bearings of unknown quality – assumed to be ABEC5, but really the test, as you say should be “is it binding or not”. My recollection that by playing with them earlier, they seemed fine, but again, I didn’t put a lot of force on them, just checked for scraping/binding under light conditions and didn’t feel anything.
I don’t know if I’d trust a Chinese manufacturers’ claimed bearing rating. They can say whatever they want but your bearing might not pass any real test. It doesn’t need to be super low friction, just reasonable and just consistent without any gritty or sticking spots that might cause the carriage to lurch.
The biggest problem I’ve run into with cheap Chinese bearings, especially linear bearings, is dimensional accuracy. I have a feeling a lot of what gets sold cheaply out of China is some QC departments reject pile.
You can try http://aliexpress.com I have found that if the item is not good they will refund the money as they cant afford a reputation loss. A new website I have just started to use is this, http://www.3dp2go.com/ball-bearing-c-69_89.html the stepper motor I got was very good. Others seem to like the quality of their parts also.