Ballscrew & Linear Rail Kit - Any Good

[A_Camera]

I quoted the SKF page to show the specs, not that they should be replaced with SKF version of the 6001Z. Of course, if one replaces the bearings one should replace them with better quality AC bearings. To replace 6001Z with similar (but better quality) 6001Z is pointless, or not a good idea.

Anyway, to be honest, I don't think you'd wear out these bearings unless you are a heavy user of the machine. Most hobby users don't run their machines for hours every day, the speed is low (even with fast servos) and is very far from the performance top of those bearings so wearing out will take time. But sure, eventually they may wear out, and in that case they should be replaced, but as I said earlier, replacing is easy and can be done when needed, will result in a few minutes of work per screw, so no big deal.

[JAZZCNC]

Anyway, to be honest, I don't think you'd wear out these bearings unless you are a heavy user of the machine. Most hobby users don't run their machines for hours every day, the speed is low (even with fast servos) and is very far from the performance top of those bearings so wearing out will take time.

Sorry but your completely wrong on this assumption because there have been many examples here on this forum of people who have bought these BK bearings and even the cheaper BK which did use AC bearings and have had Big problems with backlash caused by excessive wear within the first few months of usage.

I myself had the same issues 12+yrs ago when ball-screws and BK bearings were not commonly available, and not at all on eBay. So buying from China thru aliexpress was the only choice. I myself and many others at that time nearly always had to shim and tweak the bearings and these were AC but low quality and poorly fit, often fit the wrong way around. And I'm sorry to say nothing has changed in this respect with these BK bearings and in fact, I have noticed over the years it's actually got worse.?

To satisfy the demand for cheap kits they started fitting them with deep groove bearings which like I've said above are completely unsuitable for CNC, Esp low spec Machines even more so because they often don't have the excess power to compensate for the excessive friction caused by preloading the bearings enough to eliminate backlash.
It's a catch 22 position.? If you DON'T preload you have backlash, if you DO preload the bearings can not handle the lateral loads and wear excessively. Then throw into the mix the constant checking adjustment to keep backlash out of the machine and it quickly becomes obvious why they are best avoided.

Anyone who thinks differently is just fooling themselves and others.


The 6001ZZ or any other deep grove bearings will easily handle the RPM's but that's not what kills them it's the lateral loads, they are not designed to take lateral loads and virtually all the load on a ball screw is lateral and it's this that kills them quickly.